Growing Roses in the Bay Area
When to Plant:
Potted roses can be planted any time of year, though the best selection is available for purchase December through May. Bare-root roses are available in December, and must be planted immediately after purchase.
Where to Plant:
Full sun is best. Too much shade will discourage flowers and encourage fungal diseases, although there are certain varieties that tolerate partial shade (ask us for a list of these).
How to Plant:
In pots: Most roses need very large pots, at least 20″ tall and deep. We recommend using varieties that don’t grow more than 4′. Use a premium commercial potting soil, such as Whitney Farms, and you may mix in additional organic matter such as the Rose Planting Mix. Water well after planting, and be sure to fertilize once a month during growing season.
In the ground: Dig a hole approximately 2′ deep and 2′ wide. Fill hole with water, then let it drain. Mix backfill with 1/2 Rose Planting Mix. Place the rose in the hole so that when you backfill the hole, the bud union will be covered by 2″ of soil. We prefer this method for 4 reasons:
- It discourages rootstock suckers.
- It encourages grafted roses to form their own roots, which, in the long run, increase the plant’s viability.
- Roses seem to put out more canes when the graft is buried.
- It looks more natural and aesthetically pleasing to have several canes coming out of the ground than to have a dried-out looking graft bulge above the soil’s surface. Roses grown on their own roots should be planted at the same level they are in their nursery container. Water well after planting. Mulch with at least 2″ of mulch to help conserve water and keep the weeds down.
- In pots: Check the plant several times a week. Water when the soil is dry 1/2 inch down. Water deeply (more than a sprinkling). It’s especially important when the rose is young not to let the roots get too dry. Roses in containers will need watering more often than roses in the ground.
- In the ground: Water established plants deeply at least once a week (more often in hot or windy weather, less often during cool foggy spells). Soaker hoses snaked between the plants will make watering less of a chore and they can be hidden with mulch. Adding 2′ or more of mulch around the roses will reduce the need for water by preventing evaporation.
In early spring, when the rose is showing first signs of growth (usually late February or early March), feed with an all-purpose Rose & Flower food. This is also a good time to give the plant Epsom Salts (magnesium sulfate) to prevent magnesium deficiencies. Continue to feed repeat bloomers with the rose food every month through the end of October, and always be sure to water well when fertilizing to avoid burning the plant. You may want to occasionally substitute alfalfa meal or fish emulsion, to broaden the spectrum of nutrients. Over-feeding with strong fertilizers like Miracle-Gro can promote too much fast growth, which will be soft and particularly vulnerable to aphids and powdery mildew, so frequent feedings with a lighter organic fertilizer are preferable. For the plant’s final feeding in October, give it a dose of 0-10-10 fertilizer (too much nitrogen at this time can produce tender new growth which will be damaged by cold weather) and a second feeding of Epsom Salts. Mulch the plants for winter, and don’t feed again until spring.
Hybrid Tea roses and Floribundas should be pruned down hard in January. These roses bloom on new wood, so proper pruning encourages more flowers and also helps prevent diseases from wintering over. Climbers and arching shrub roses should not be pruned so severely, since it would destroy their naturally elegant shape. Remove any dead or weak wood, and thin the plant to maximize air circulation and sunlight. Once-blooming roses should be pruned in summer, right after they have flowered. Most roses benefit from being completely defoliated in winter, to encourage a deeper dormancy and to remove diseased tissue. Climbers and arching shrubs should be trained to grow horizontally or diagonally, since vertical canes will only bloom on the tips. Training encourages flowering lateral shoots to develop all along the canes.
If you have chosen disease resistant varieties that thrive in our climate, it should be possible to grow beautiful roses without using any dangerous toxic sprays.
- Aphids: Knock them off with hose water, use insecticidal soap, or spray with horticultural oil.
- Spittle Bugs: Knock them off with a high-powered spray of water from the hose.
- Rose Slugs: These are the larvae of the Sawfly, which eat lace-like holes in the leaves. Spray with an insecticidal soap that contains Pyrethrins, making sure to hit the undersides of the leaves.
- Powdery Mildew: At the first sign of white powder on the leaves, spray with a mixture of 2 Tbs. Horticultural Oil in one gallon of water. Spraying every ten days will coat the leaves with a film of oil that prevents mildew spores from attaching.
- Black Spot: Remove any affected leaves as soon as they appear. Thin the growth to allow maximum air circulation and sunlight. Spraying with horticultural oil or sulfur may help prevent further outbreaks. If you have to defoliate a bush after a severe case of black spot, feed it weekly with fish emulsion to encourage new growth: most roses will be good as new within a couple of weeks.
- Rust: Remove affected leaves as soon as you notice them. Remove and destroy any leaves closer than 18″ to the ground. Maximize heat, sunlight, and air circulation. Clean up all debris beneath the plant, and add a 1″ layer of fresh mulch every three months.
- In General: A winter spraying of lime sulfur and dormant oil can help prevent insect and fungal problems. Plants that are well fed and watered will be stronger and more resistant. If diseases persist, you might want to consider replacing the rose with a less susceptible variety (ask us for a list of these), or just learning to live with the disease at certain times of the year.
Above all, remember that roses are meant to be enjoyed!