Container Size. Most roses grow well in containers as long as root space is sufficient and care is appropriate. Containers of at least 2 to 2.5 feet in depth and at least 15 to 20 inches in diameter are recommended for full-sized rose varieties, and generally the deeper the better for rose health, growth, and blooming. Roses planted in pots and containers generally do not grow as large as those planted in the ground; 4-to-6-feet-tall plants may be the maximum reasonable size range for roses in all but the largest containers.
Container Location. Container roses should be placed in a location receiving a minimum of six hours of sun. Clay pots will help to keep rose roots cool during hot summers, but clay and terra cotta tend to wick moisture from soil and therefore require more watering than their plastic counterparts. Dark-colored or black pots will tend to heat up and may stress or fry rose roots during hot weather in your zone, especially at five-gallon nursery-pot size and smaller.
Planting Method. When planting roses in containers, be sure that sufficient soil is added to completely cover roots to the root crown. Mound soil slightly and monitor over the next few weeks and months to be sure that soil levels do not settle sufficiently to expose roots.
Rose Varieties. Large rose varieties, including many climbers and shrub roses, generally should not be grown in containers but may perform reasonably well in large containers or planters of 2.5 to 4 feet in depth.
Miniature roses are particularly well-suited to containers. As always, be careful when making your selections: miniature roses often come in small pots and have small leaves and flowers, but this can be misleading as an indication of eventual plant size. Mini roses may grow to over 3 feet in height and become too large for the space or container originally selected. For a complete description (including size) of those miniature roses that will do well in your zone, go to GardenZeus and enter your zip code, then go to Recommendations for Miniature Rose Varieties in California. Any of the described miniature varieties will work well in containers provided that they do not grow to over 2 feet in height.
“Miniflora” roses are larger than miniatures and are bred specifically for rose shows. They tend to have ungainly structures that don’t work well in containers, or in most garden settings.
Resist the temptation to purchase for garden use the cute or inspiringly lovely potted miniature roses you might see in the grocery store checkout line or in other impulse-sale areas: these roses may not be suitable for your climate and growing conditions. GardenZeus recommends purchasing known rose varieties that are suitable for your zone from a reputable nursery or mail order source.
Nutrient Needs. Roses are heavy feeders and container roses may need more frequent applications of nitrogen, amendments, and/or fertilizer than their in-ground counterparts.
Companion Planting. Roses in containers will generally be grow most successfully when they aren’t competing for root space with too many other plants. While attractive groupings of roses, perennials and annuals are possible, be judicious about crowding roses in containers. Possible companions for container roses include alyssum; low-growing monocots; and small, well-behaved ornamental grasses, especially in colors that compliment or contrast with your specific rose bloom colors.
For common problems associated with growing roses in containers, see Growing Roses in Containers: Common Problems.