Bougainvilleas: Essential Pruning and Maintenance

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by Ann Clary with C. Darren Butler

What makes bougainvilleas so appealing to gardeners around the world? Undoubtedly the profusion of colorful and long-lasting flower bracts, the specialized leaves that are often mistaken for blooms or petals. In Mediterranean and mild-winter California areas, bougainvillea are a signature landscape plant, offering their profuse displays in a range of colors including pink, purple, magenta, white, yellow, orange, and red. The true flowers are small and inconspicuous, white or cream colored, and nestled within the colorful bracts. Bougainvilleas are much loved for their exuberant and lasting display of summer color at a time when many other plants are suffering in the Southern California summer heat.

Bougainvillea plant cascading over wall

Bougainvillea plant cascading over wall

 

Pruning. Bougainvilleas produce their flower bracts or “bloom” on new growth. Frequent or at least annual pruning is important to encourage new growth that will produce the colorful bracts. Overgrown, neglected, enormous, thorny bougainvillea shrubs are a candidate for the worst-ever pruning nightmare. Older bougainvilleas tend become dense as dead leaves, spent bracts, old twigs, and other plant matter accumulates to form thatch within their twiggy interiors. Neglected bougainvillea may produce unwanted conditions such as taking up too much space, becoming difficult to manage and prune, becoming too large or heavy for supports, providing an almost-unassailable home for rodents, and losing their colorful and attractive appearance. The dense inner woody twigs and branches take up space and lack aesthetic value—and they don’t produce the lovely bracts.

It is particularly important to prune bougainvillea regularly to maintain reasonable branch structure, keep them manageable, and avoid tall, heavy, and/or unruly shrubs that put out little new growth each year and bloom only occasionally or minimally. Bougainvillea naturally produce many main stems that can become a tangle within just a few years. Vines can be pruned at almost any time of year except during periods of hot weather or frost.

Don’t hesitate to cut back larger, older stems as needed for good structure, or to provide a hard structural pruning every few years. Frost-free periods from winter through early spring when plants aren’t actively blooming are ideal for major pruning. Reasonably skilled structural pruning is important for bougainvillea. Hire a professional or take the time to learn proper structural pruning.

Simple pruning involves removing snipping here and there for shaping, cutting back generally to encourage new growth, and removing unwanted stems to encourage whatever permanent form is desired. To train your plant into an espalier or to direct it to grow and bloom in a specific location, attach selected larger branches to support and remove the smaller branches growing in the wrong direction. If you want your bougainvillea to grow on a fence, weave small and young branches throughout the links or open spaces. Remove or redirect uncooperative branches.

Trunk of old bougainvillea plant

A tangle of main stems on old bougainvillea plant

 

Mature bougainvillea plant with interior thatch

Mature bougainvillea plant with interior thatch or plant debris

 

Bougainvilleas are one of those plants that benefit from frequent or almost constant cleanup and light pruning to keep them manageable and maintain their shape, including pinching back, light trimming, training, and cleaning up dead leaves and stems. Pinching or snipping off the tips of new shoots is an easy way to shape smaller plants to be more full and bushy, and is especially recommended for shrubby cultivars.

Bougainvilleas naturally follow a cycle of blooming followed by a rest period. Healthy plants that aren’t overwatered repeat this cycle during the warmer and drier parts of the year. Dedicated cleanup and moderate pruning is recommended during the rest period after every bloom cycle.  Monitor or notice blooming to time your pruning during the rest period that follows.

Beware of maintenance gardeners who use hedge trimmers on bougainvilleas unless you want square or round shrubs and hedges! This practice may regularly remove the new growth needed to produce the colorful bracts, produce unattractive views of sheared stems, and tend to maintain bougainvilleas as nonblooming and nondescript green/brown shrubs.

Remember that pruning bougainvilleas can be a dangerous task: they have thorns! Gardeners should tackle bougainvillea pruning with a pair of pruners, loppers, heavy gloves, hat, eye protection, long sleeves and long pants.

 

Soil Amendments. Bougainvillea bloom best during warm weather after several weeks with little or no water and fertilizer, followed by generous watering and fertilizing. Allow dry periods, then fertilize with organic manures, compost, and/or a balanced fertilizer for blooming perennials while also increasing water. Bougainvillea plants will often perform well throughout summer and into fall if fertilized once in late winter or early spring.

GardenZeus has customized gardening information by plant and zip code. To get started, enter your zip code here.

Other articles of interest include:

Bougainvillea: An Ideal Plant for Hot Mediterranean Areas

Constructing a Mediterranean Herb Garden

 

 

 

What To Do in March: 10 Tasks for Southern California Gardeners

by C. Darren Butler with Ann Clary

March is typically one of the busiest months in the Southern California garden. Regardless of whether you live in one of Southern California’s inland valleys or along the coast, here are 10 items that should be on your gardening to-do list this month:

  1. Cut back or replace diseased, leggy, overgrown, unproductive, or troublesome perennials, preferably before new growth begins. Consider adding drought-tolerant plants wherever watering and fertilization can be managed appropriately.
  2. Plant warm-season annual vegetables and flowers. Early-spring weather has been unusually cold and wet this year (2019) in Southern California, so be cautious with starting seeds directly outdoors when temperatures are below 70° F. Many seed varieties may tend to rot before germinating in cold, wet weather, and some may have low germination rates when temperatures are below 80° F. Start seeds indoors and transplant starts outdoors. Start seeds as soon as possible. After a late, cool and wet winter this year, Southern California may have rapid or sudden shifts in temperature to warm or hot weather in March or April that could stress seedlings and make vegetable gardening difficult.
    bean seedlings

    bean seedlings

     

  3. As weather warms, monitor emerging warm-season pests such as snails, slugs and aphids. Despite a generally cool February and March in 2019, most Southern California areas received little or no frost, so larger-than-usual numbers of adult insect pests and eggs may have survived the winter in inland areas. Southern California may see rapid population growth with insect pests and severe pest pressures on garden and landscape plants after warmer weather arrives.
  4.  Monitor recent transplants regularly, at least every 2 to 3 days during cool-to-warm weather to catch wilting, irrigation, pest, disease, weed, and other problems early.
  5. Maintain or add mulch. Be cautious with adding mulch before seedlings emerge. Use fine and medium mulch such as straw, pine needles, yard clippings, and coffee grounds in new spring beds. Keep wood-chip mulch at least 30 feet from wooden buildings whenever possible to minimize the chance of termites moving from mulch to buildings.
    Mulch

    Mulch

     

  6. Harvest vegetable thinnings, last winter crops, and earliest spring crops. Cut early spring flowers for harvest.
  7. Irrigate variably depending upon rain frequency and volume; turn off irrigation during rainy periods. Provide consistent soil moisture. With the significant volume of rain in Southern California from February and March of 2019, irrigation of smaller trees and established perennials might not be needed for at least several weeks. With water held in soil, larger trees may need no further watering until early summer to midsummer or later.
    Drip irrigation

    Drip irrigation waters deeply

     

  8. Provide  shade during early heat waves; see GardenZeus Tips for Shading Vegetables During Hot Weather for creative ideas for providing shade.
    shading plants

    shading plants

     

  9. Apply organic nitrogen as plants show new growth. Add organic nitrogen such as manures as dormant fruit trees begin breaking bud, and as annuals and perennials show new winter/spring grown or once established as seedlings. Avoid fertilizing dormant trees, perennials, and new seedlings.
  10. Finish last pruning for dormant fruit trees and roses. Prune citrus anytime from winter through early summer when trees are not flowering or bearing fruit and when weather is cool to warm.

GardenZeus has customized gardening information by plant and zip code. To get started, enter your zip code here.

Other articles of interest:

Maintaining Citrus Trees in the Spring: Six Tips

Spring Maintenance: Roses, Lavender, and Bearded Iris

Heavy Feeders and Spring Planting

Starting Vegetable Seeds: A Concise Guide

GardenZeus receives commissions for purchases made through links in this post. There is no additional cost to you.

by Ann Clary and C. Darren Butler

Why start your own seeds?

Better selection. Availability of seedlings may be painfully limited at local garden centers, and they don’t always stock the best varieties for your area or the particular variety that suits your needs. Many new varieties, heirlooms, and disease-resistant varieties, such as mildew-resistant zucchini, that might produce well or offer other benefits in your garden must be started from seeds.

Healthier Plants. When started from seeds, plants adapt to your soil and current environmental conditions such as temperature, sunlight, and soil moisture. Purchased transplants may be root-bound when still small, and never produce well.

Avoid Chemicals. Start your own seeds and you can be sure that your vegetable plants are never treated with pesticides or chemical fertilizers.

Cheaper. Starting from seeds is usually the the most economical option for any vegetable. This may vary based on many factors as compared to purchasing starts from your local garden center. Do you already have seed starting materials? Are you starting many seeds for a large crop or do you just need 1 or 2 plants?

Learning and fun. See new life emerge from the soil as seeds germinate, watch starts grow under your care, and learn from what works and what doesn’t.

Remember—some vegetable plants dislike root disturbance and don’t transplant well; they should be planted directly in the soil, not transplanted from seed containers. Root vegetables, such as carrots and beets, many cucurbits such as squash and melons, and legumes such as peas and beans among others typically are not good candidates for transplanting and should be seeded directly into prepared soil.

Timing

Starting vegetable seeds at the right time of year in Southern California is important for optimal plant health, and abundant harvest. Plant too early and some vegetables may suffer in cold late-winter or spring weather. Plant too late, and the plant may not mature or produce a harvest before the heat of summer arrives.

To start seeds you’re a going to need a few—but not many—supplies.

Seeds

GardenZeus recommends open-pollinated, untreated, organically grown seeds. For additional information on choosing seeds for your area, see How to Choose the Best Seeds for California Gardens and Common Terms for Seeds and What They Mean.

Containers

Seed starting containers range from repurposed home items to specialized seed trays.

Repurposed home items save money but may be awkward or less than ideal for seed starting. Plastic containers and milk cartons aren’t biodegradable and might no longer be recyclable once modified for seed starting. Homemade paper and cardboard containers tend to fall apart from moisture. Eggshells and egg cartons may also break or fall apart, and soil may dry out quickly in any small seed-starting container. Small clay flower pots are awkward or inefficient for starting large quantities of seeds, although they can be a solution when starting a small number of seeds.

GardenZeus does not recommend either peat pots or peat pellets often sold at garden centers. Plant roots do not necessarily penetrate the bottoms of peat pots and the individual containers dry out quickly. Peat pellets are expensive and cannot be reused. And most importantly, harvest of peat moss causes environmental damage to wetlands, reduces capture of carbon from the atmosphere, and accelerates climate change.

Six-pack seedling containers are an inexpensive option. GardenZeus recommends cells that are at least 2 inches deep for sufficient root space and better moisture retention.

Flats are preferred by many gardeners for organizing and managing six-pack cells, especially indoors or anywhere water can’t drain freely, and are reusable almost indefinitely.

Seed Starting Mediums

Seed-starting mediums are NOT the same as healthy soil.  Seed-starting mediums do not have to be fertile or rich in nutrients, but they do need to be loose enough to work with easily and allow for aeration (air flow between the soil particles). Ideal seed-starting soil will retain moisture but not get waterlogged.

Gardeners can use formulas or purchase commercial potting soil mix. GardenZeus recommends a mix of 1/3 washed sand, 1/3 compost, and 1/3 soil from your garden. If soil-borne disease or insect pests have been a problem, sterilize garden soil by baking in an oven for 20 to 30 minutes at 200 degrees before adding sand and compost. Sterilizing soil also kills weed seeds—and kills the microbial life that is so important to plant health and vigor. Experienced seed-starters often formulate their own mix using combinations of any of the following: horticultural vermiculite, perlite and filtered garden soil or sifted compost. Many gardeners prefer to avoid using perlite or vermiculite in their seed-starting mixes; both vermiculite and perlite require significant energy to produce. In addition, other products, such as coir or recycled paper fiber, are perceived as from reusable or renewable resources.  Commercial seed-starting mixes may be convenient or preferred by many gardeners.

Regardless of using a homemade formula or commercial mix, GardenZeus recommends that gardeners avoid using peat moss (see “Containers” above).

Preparing Seeds

Keep in mind that some seeds benefit from presoaking while others may benefit from presprouting. See specific plant information for more details.

Planting

GardenZeus recommends moistening or presoaking the seed starting soil or medium before planting. If planting in flats or directly outdoors, place the individual seeds according to the recommended spacing for each plant. Many gardeners prefer to plant several seeds per compartment in six packs and thin to the single strongest seedling. A reasonable rule of thumb is to cover seeds to a depth of 2 to 3 times their diameter or width (the smaller dimension when a seed is placed on a flat surface). If planted too deep, seedlings might be slow to emerge or have difficulty growing to the surface. If planted too shallow, seeds may be prone to drying out or produce an exposed or weaker root system.

After planting GardenZeus recommends covering seeds with sand, light potting soil, or seed-starting medium and misting or watering.

To optimize seed germination, provide sufficient and consistent moisture and proper temperature.

Temperature

Most vegetable seeds germinate well in warm indoor areas at about 70 to 85 degrees. Some seeds need limited or specific soil temperature for best germination. Bottom heat can work wonders for improved germination. Many gardeners use heated seed-starting mats below their trays. Remember, it’s the soil temperature that matters, not air temperature.

Moisture

Keep the planting medium moist but not wet. Depending on size and age of seedlings, texture of the soil or planting medium, humidity, and temperature, this may require misting or watering as many as several times per day. Some commercial seed starting systems use a cover to increase humidity, retain moisture, and reduce watering frequency.

Other commercial products contain a continuous self-watering system to ensure that the seeds receive continuous moisture.

Grow lights can help to provide the abundant light indoors that seedlings need, especially when seedlings will be grown for days or weeks before transplanting. Grow lights have little or no effect on germination, but they can be help to support healthy and vigorous growth after seedlings emerge.

GardenZeus has customized growing information by plant and zip code. To get started, enter your zip code here.

Early Spring Planting: 3 Ideal Vegetables

Heavy Feeders and Spring Planting

Spring Gardening: 5 Tasks You Shouldn’t Forget

 

Warm Season Vegetables: Can They Be Transplanted?

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Some warm season vegetable plants are sensitive to root disturbance; gardeners should plant these vegetables directly outdoors after weather warms in the spring. Other warm season vegetables make excellent candidates for seeding into small pots or containers for later transplanting.

Solanums. Solanums, including tomatoes, peppers and eggplants are not sensitive to root disturbance and are ideal candidates for transplant. Gardeners may place seeds for tomatoes, peppers and eggplants  directly into small pots for later transplanting. Of course, seeds can also be started directly outdoors when risk of frost is low and daytime spring temperature are sufficiently warm. Different vegetables have different cultural requirements, including daytime temperatures. For more complete cultural requirements of different solanums, see tomato, pepper, hot and pepper, sweet.

Cucurbits. Unlike solanums, most cucurbits, including summer squash (including zucchini), winter squash, cucumbers and melons are sensitive to any root disturbance, such as from transplanting. Surface cultivation, digging, harvesting root crops, thinning, or weeding near established plants may also cause root disturbance to cucurbits. From the time of germination onward, it’s generally best to avoid all root disturbance as much as possible for all cucurbits. Seed cucurbits directly outdoors, when daytime temperatures are sufficiently warm. For more complete cultural requirements of different cucurbits, see summer squash, winter squash, zucchini, pumpkin and cucumber.

Corn and Beans. Like cucurbits, corn and beans, both pole and bush, are sensitive to root disturbance, including from transplanting. Again, like cucurbits, seed corn and beans directly outdoors, when daytime temperatures are sufficiently warm. For more complete cultural requirements, see corn, bean, pole and bean, bush.

Early Spring Planting: 3 Ideal Vegetables

Heavy Feeders and Spring Planting

Spring Gardening: 5 Tasks You Shouldn’t Forget

GardenZeus has comprehensive, customized growing information by plant and zip code. To get started, enter your zip code here.

Planning Vegetable Gardens in Mediterranean Climates: 3 Common Mistakes

Planning a spring garden

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This time of year, many gardeners in California’s coastal and inland valley areas, commonly described as Mediterranean climates due to their moderate, wet winters and warm, dry summers, are in the process of planning their vegetables gardens for spring and summer.  Here are three common mistakes:

Choosing the wrong plants. Pictures in national gardening media can be enticing, but plants that require extended periods of moist soil and moderate, humid temperatures (tropical plants) are generally not a good choice for gardeners who live in California or other Mediterranean climates. So no matter how much you may want to grow your own ginger or turmeric or peanuts, most California gardeners are going to struggle with these plants and reap a limited harvest. Gardeners who want to make the extra effort may be successful growing some of these plants in  containers, where specific micro climates can be carefully controlled and modified.  See Ginger: Growing and Harvesting for Culinary Use and Turmeric: Container Gardening and Harvesting. Gardeners who live in Mediterranean climates can successfully grow many of the jewels of the home herb and vegetable garden, such as tomato, corn, lettuce, basil and pumpkin. Why not choose one or more of them?

tomato

Tomato ready for harvest.

 

Choosing the wrong varieties. Keep in mind that even for the same plant, there are typically many varieties with an array of characteristics. Gardeners who live in inland valleys will generally want to select heat-tolerant varieties that will last well into the summer; gardeners along the coast will typically want to grow “early” varieties that don’t require as much heat to fruit and ripen. And each area will have a slightly different palate of pests and diseases. For example, gardeners along the coast are typically more concerned with mildews and purchasing mildew resistant varieties can be critical to success. Seed catalogs and packaging labels in garden centers typically describe a particular variety’s resistance to specific diseases. For a complete guide see Common Terms for Seeds and What They Mean. 

Planting too early or too late. Plant too early and small plants may struggle in cool, wet weather. Plant too late, and plants may not have time to develop root systems necessary to pull enough water from the soil on hot summer days or develop leaf canopies large enough to protect ripening fruit from summer sun.

Planting too late can results in stress.

Planting too late can results in stress.

 

Gardeners in most of the United States plant spring seeds based on their USDA zone. However, USDA zones are inadequate for making informed decisions about what to grow in California because they are based on average annual minimum winter temperatures only, and do not take into consideration other critical factors for California gardening and landscaping, such as summer and winter high temperatures, annual rainfall, humidity, overall climate and seasonal changes in climate, or the number of days annually of hot weather or frost. The USDA zones place portions of Los Angeles in the same zone as San Francisco, despite the vastly different growing conditions, temperature ranges, climates, and high temperatures between those two cities. Much of California’s coastal inland and valley areas are frost free, so using minimum winter temperatures and USDA zones are generally not helpful. For this reason, GardenZeus uses a climate zone system optimized for California and for your individual zip code. To take complete advantage of GardenZeus resources for California gardening, go to GardenZeus, enter your zip code and select plants. For a complete explanation of GardenZeus climate zones, go to California Climate Zones.

And remember: heirloom and open-pollinated varieties typically have a longer time to maturity than many hybrids and need to be planted before many hybrids and “early” varieties of the same plant. Seeds catalogs usually list number of days to first harvest or maturity, sometimes listed as just a number (70 days), usually meaning the average number of days from the time the seed sprouts or the seedling emerges from the ground to the time fruit or flowers can be harvested. If you are planting in new or infertile soil, are new to gardening or inexperienced with the vegetable that you are planting, or working under challenging gardening conditions, the actual time to maturity may be longer than listed in seed descriptions, and in some cases much longer. To arrive at the total number of days from planting the seed to maturity, you need to add the germination time, which varies widely for different vegetables and flowers but is most commonly about a week or two. For more information, see How to Choose the Best Seeds for California Gardeners.

GardenZeus has comprehensive, customized growing information by plant and zip code. To get started, enter your zip code here.

 

New Year’s Resolution: Grow California Native and Mediterranean Plants

by Ann Clary and C. Darren Butler

GardenZeus receives commissions for purchases made through links in this post. There is no additional cost to you.

New Year’s Resolution 4: Grow California Native and Mediterranean Plants.

Will plants sold at local gardening centers and nurseries thrive in your garden or landscape? Often they will, but in some cases, climatically inappropriate plants are sold locally. For other plants, the unique conditions in your landscape might be problematic for a plant that will thrive at another location in your neighborhood or city.

This question is even more important when purchasing online or by mail. Many to most ornamentals, fruit trees, berries, and other perennials purchased from outside of California may fail to thrive, bloom, or produce a harvest in our Mediterranean-climate areas.

Native plants from California and other Mediterranean-climate areas can provide a solution. They are adapted to survive and thrive in the many unique climates and micro-climates in California. We often tend to associate California natives with a limited range of drought-tolerant species that are commonly used in home landscapes, many of which are suited to mild, wet winters and warm-to-hot dry summers. However, it’s important to remember that California has thousands of native plant species, including many natives that need frequent watering, high or low elevations, or other specific environmental or climate conditions. Considering California natives narrows your choices to plants that are known to thrive California, but you still need to confirm suitability of native or California-friendly plant species for the location and micro-climate where they will be planted.

California natives offer many advantages to the gardener. Here are a few:

1. Use less water. California and Mediterranean natives are often drought-tolerant, and may need little or no watering once established. Many native species have special adaptations or mechanisms that allow them to survive hot and dry summers, such as going dormant. How much would you save on your water bill if you eliminate all or almost all irrigation for landscape ornamentals?

2. Minimize the use of fertilizers and soil amendments. Many California natives thrive in the moderately alkaline, poor-to-moderately-fertile soils that are common in California. They may be harmed or killed in fertile, microbially active soils with high levels of organic matter that are needed for food gardening and growing many non-native ornamentals. Soils in California’s low-rainfall areas tend to be naturally low in organic matter and may never become loamy or highly fertile without human intervention. Imagine it! California native plants generally do well in the soils here, and they usually don’t need the endless bags of amendments, applications of compost, and other amendments and fertilizers.

Hummingbird Sage

Hummingbird Sage

3. Reduce pests and diseases. Reduce use of pesticides and chemicals. When grown appropriately and not overwatered or over-fertilized, California native plants often have fewer problems with pests and diseases than non-native ornamentals, and may be easily harmed by pesticides and other chemicals. Native plants and landscapes often tolerate or need few-to-no applications of pesticides and chemicals. 

4. Less maintenance. When native species are chosen carefully and are well-suited to their growing environments, many require minimal input from gardeners as compared with non-native ornamentals. Natives accommodate your busy lifestyle by not needing as much from you, and allow you to spend time relaxing or enjoying the beauty of your garden.

Why struggle with holly when you can grow Toyon easily?

Why struggle with holly when you can grow Toyon easily?

5. Ecosystem and biodiversity benefits. Native plants feed and provide habitat for native birds, animals, and insects, including pollinators. Some native shrub and tree species potentially provide benefits to dozens or hundreds of bird and insect species. Home gardeners can help maintain biodiversity in California and provide other ecosystem benefits by growing natives at home.

 

A bee on Ceanothus.

A bee on Ceanothus.

GardenZeus has customized gardening information by plant and zip code. To get started, enter your zip code here.

 

10 January Tasks for Mediterranean Gardeners

GardenZeus receives commissions for purchases made through links in this post. There is no additional cost to you.

Many might think of January as a slow month in the Mediterranean garden, as even in mild Mediterranean climates, January often brings cool, rainy weather. Yet there is much to do in January to prepare plants for their burst of growth when the weather warms in the spring. For a customized list of gardening tasks by plant and month, find your GardenZeus Climate Zone. 

Here are 10 tasks all gardeners in Mediterranean climates should have on their January to-do lists:

  • Monitor plants regularly, at least every 2 to 5 days during cool-to-cold weather to catch wilting, irrigation, pest, disease, weed, and other problems early.
  • Plant bare-root roses, fruit trees, vines and berries.
  • Prune roses and deciduous fruit trees.
  • Protect plants from possible frost: water thoroughly and protect plants with fabric, cardboard, paper, or plastic sheets during periods of overnight frost.
  • Maintain or add mulch to garden beds.
  • Harvest citrus trees and winter vegetable crops.
  • Irrigate variably depending upon rain frequency and volume; turn off irrigation during rainy periods.
  • Add appropriate amendments and/or organic fertilizers for actively growing and/or blooming plants. Avoid fertilizing dormant plants and trees.
  • Order seeds for spring annuals and spring and summer vegetables.
  • Start seeds indoors for later transplant outdoors, such as tomatoes, lettuce, and chard.

GardenZeus recommends seeds from Botanical Interests:

Other articles of interest:

New Year’s Resolution: Focus on Soil, Not Plants

New Year’s Resolution: Compost More Waste

New Year’s Resolution: Water Plants and Trees Deeply

Rain! Rain! Rain! But is it Enough to Water Plants?

GardenZeus has customized information by plant and zip code. To get started, click here.

 

New Year’s Resolution: Water Plants and Trees Deeply

New Year’s Gardening Resolution 3: Water Plants and Trees Deeply.

“How often and how much do plants and trees need to be watered?” is both one of the simplest and most-complex questions for gardeners.

The simple answer is that most plants should be watered to the entire depth of their roots, then not watered again until soil dries out to some degree, which varies by species.

The complex answer involves many factors and variables, including plant species, soil texture, and seasonal temperatures.

Sprinklers are useful for watering lawns and some small bedding plants, but are unsuited to watering almost all other plants and trees.

Reasons to avoid shallow, frequent irrigation:

– Plant roots grow where the water is. Shallow, frequent watering over time concentrates roots, even for large trees, in the top few inches of soil, where they may dry out rapidly and need frequent watering. Roots near the soil surface are most susceptible to pests, diseases, and injury.

– Spray irrigation or frequent wetting of stems and foliage encourages pests, diseases, and weeds.

– Shallow water results in greater evaporation with negative results, including faster accumulation of soil salts as minerals in municipal water are left behind in soil as water evaporates.

Slow, deep watering has many possible benefits including:

– Deeper, firmer rooting for trees and shrubs. Deeper roots increase a plant’s drought tolerance.

– Reduced evaporation and runoff.

– Reduction in pests, diseases, and weeds.

– Potential reduction in water use.

To water deeply, use a drip system or a trickle from a hose at a rate slow enough to prevent runoff. Many larger garden plants and landscape shrubs will benefit from slow watering for several minutes to an hour or two depending on plant size, soil texture, and watering rate/volume.

Drip irrigation used to water squash plant

Drip irrigation used to water squash plant

Learning to water your established trees and large shrubs takes time and observation. Irrigation volume and frequency vary by species and plant size. Observe shrubs and trees for early signs of drought stress, such as slight curling or drooping of leaves, then water deeply. If established trees need water again sooner than a few weeks, increase watering duration and/or volume.

In California Mediterranean-climate areas, many large shrubs and trees should be watered only once every few-to-several weeks during warm weather, and less often during cold weather, especially with occasional winter rainstorms. Trees should be watered at or just inside the dripline (the edge of the canopy).

Water penetration in soil can be evaluated by pressing a long screwdriver or thin metal probe into soil and noticing when soil resistance changes as dry soil is reached. This method can be used to gauge how fast water infiltrates to a foot or two in depth for a given method of irrigation. A shovel can also be pressed carefully into the soil outside or at the edge of an established plant’s root system to expose the soil profile and gauge depth of roots. For gardeners who want more precision and less guesswork, GardenZeus recommends a professional quality moisture meter inserted at the edge of the root system. (Picture below.)

Water spreads as it infiltrates into soil, narrowly in sandy soils and more widely in clay soils. If it takes your drip system or a trickle from your hose 1 hour to deliver water to a foot in depth in clay soil, it’s a reasonable guess that it should take about 6 to 8 hours of watering using the same method to deliver water to 4 to 5 feet in depth for a larger tree.

GardenZeus has customized gardening information by plant and zip code. To get started, click here.

Other articles of interest:

Rain! Rain! Rain! But is it Enough to Water Plants?

Chlorine, Soil, and Watering Gardens (Chlorinated Water, Part 1 of 2)

Remove Chlorine When Watering Organic Gardens (Chlorinated Water, Part 2 of 2)

New Year’s Resolution: Compost More Waste

New Year’s Gardening Resolution 2: Compost More Household and Garden Waste.

All life on Earth is made of the same building blocks, the organic elements. These include carbon, hydrogen, nitrogen, and many more that are recognizable to gardeners. Composting is the process of breaking down organic matter, which is any material that was once alive as part of a plant or animal, so that the basic building blocks can be reused for new life.

Composting occurs naturally in soil, at soil surfaces, and in nooks and crannies everywhere in gardens. Soil organic matter can be increased when cleaning up gardens by cutting expired plants at the soil line and leaving roots in soil to decompose. Quality compost is high in humus and humid acids, which contain the building blocks of plant life in ideal form for plant roots to absorb them.

Most of us can do better with being more thorough about composting. Enormous volumes of organic matter that could have composted are sent to landfills as household and yard waste. This has many polluting and negative environmental impacts, from the manufacturing and gasoline required to operate garbage trucks to otherwise reusable organic matter becoming toxified for the long term in landfills when it mixes with toxic chemicals and substances, toxic metals, commercial and manufacturing waste, and other toxic trash. Organic matter that has been cycling through life on Earth for millions of years may be tied up indefinitely in our human landfills once mixed with toxins.

Compost pile decomposing

Side view of compost pile in various stages of decomposition

 

Most gardeners know that they can compost apple cores, citrus peels, banana peels, and most food wastes but what about the following?:

– Eggshells: GardenZeus Expert Darren Butler considers eggshells to be the best source of calcium for soil and gardens. For many gardeners, they are too precious to put directly into a compost pile, and are used instead to provide extra calcium directly in soil or under mulch near tomatoes and other garden plants.

– Human hair and pet fur: Hair and fur contain nitrogen. They may break down slowly in compost.

– Pet bedding such as wood shavings from cages or aquariums

– Paper towels, napkins, and tissues

– Newsprint and newspapers: Most major newspapers in Southern California have been printed with non-metallic inks for years. Colored or glossy newsprint may contain pollutants. Check with your newsprint source.

– Paper and cardboard, especially with minimal printing or plant-based inks: Many online sources recommend composting printed paper, but toner and inks may contain plastics or other substances that are best kept out of soil. Use caution with recycled cardboard which may be best disposed of in the recycling bin, because it may contain bits of metal, plastic, or other pollutants.

– Plant wastes: All plant wastes are technically compostable. Some may take a long time to break down in a compost pile. In most cases it’s best not to compost plant materials that are diseased or pest-infested as doing so may perpetuate these problems in your soil and/or garden.

– Corn cobs and avocado pits, anyone?: These will compost . . . eventually. They may persist in compost bins for a year or longer.

– Dryer lint: Many online sources recommend composting dryer lint. GardenZeus expert Darren Butler agrees, provided that the lint is from natural-fiber clothes such as cotton or hemp. Dryer lint from synthetic fabrics may contain nylon, polyester, or plastic bits and threads that are best kept out of your garden soil.

– Cotton balls, paper/cotton Q-tips, and discarded cotton cloth: Be sure that these are cotton rather than synthetic.

– Sweepings and vacuumings: These contain mostly organic matter under normal household conditions. Recommended for composting when your home is nontoxic and you know that there aren’t pollutants on your floors or carpets. Most carpets are synthetic and stray pieces of carpet are best kept out of the compost pile.

–  Special care or expertise is needed to compost some organic household wastes safely, without unwanted smells, and without attracting rodents, such as meats, bird or animal bones, oils, and dairy. Domestic pet wastes may contain pathogens that cause disease in humans.

Composting is a gift to future generations, and helps to perpetuate life. It’s an age-old method for providing fertility to plants, and a necessity for sustainable living today.

Don’t have a compost bin?

GardenZeus recommends the following outdoor compost bin for your household and garden waste:

This container sits on your kitchen counter and holds your household waste before you place it in your outdoor compost bin. Odor free.

Want to read more about composting and the soil food web? Look no farther than the iconic gardening book, Teaming With Microbes.

Other articles about soil and composting:

New Year’s Resolution: Focus on Soil, Not Plants

Grow Cucurbits in Mature Compost Pile

GardenZeus has customized gardening information by plant and zip code. To get started, click here.

New Year’s Resolution: Focus on Soil, Not Plants

New Year’s Gardening Resolution 1: Focus on soil, not plants.

Everything that gardening experts, books, and if you’re lucky enough to have one, a gardening parent or grandparent, have told you that you need to do for plants, you actually need to do for soil.

Are you worried about watering your plants? Shift your worry to being sure that helpful soil bacteria, fungi, and other microbes are watered appropriately, even in areas where nothing is planted.

Do you feel you need a plan for feeding and fertilizing your plants? What you actually need is a plan for year-round feeding of the life in your soil, especially at times when you aren’t actively planting, there are no living roots in your soil, or your garden is dormant. In mild-winter California areas, soil life eats organic matter year-round.

Concerned about protecting your plants from insects, wind or harsh weather, or diseases? Protect the life in your soil first.

Soil that is vibrantly alive with a complex soil ecosystem provides ideal conditions to support healthy plants in a way that dirt, or the mostly-dead potting soil you buy in a bag at the nursery, never will. For a soil ecosystem to be healthy, it must be well-fed by plant-root exudates, which are sugars and other substances released by plant roots. Soil is also fed by dead cells from plant roots and root hairs; organic matter such as mulch at the soil surface; and the wastes and decaying bodies of both microorganisms (such as bacteria) and macroorganims (such as insects and worms).

When we shift focus to soil, our plants take care of themselves, or more accurately, soil life takes far better care of them than we ever could.

GardenZeus has customized gardening instructions by plant and zip code. To get started, click here.

Tips for Testing Soil pH at Home with A Soil pH Meter

Mud Pies and Fizz: Easy Home Tests for Soil pH

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