By Gwen Kilcherr, Master Gardener
The conventional wisdom on roses is that they are temperamental, demanding and hard to care for. It is true that they have some pretty firm non-negotiables: full sun, regular water and decent drainage. Other than that, with some basic, common-sense care, anyone can grow roses that, even if they would not win prizes, will satisfy even the most critical gardener. Nothing beats a rose bush in full bloom, unless it is the bouquet that is cut and brought inside. For those gardeners who are focusing their efforts on low-water gardening, roses can be grown very successfully in containers, adding lushness and bloom to the patio or deck.
Caring for your Roses
There are many different types of fertilizers to choose from: slow-release fertilizers, such as Osmocote, release nutrients slowly into the soil over a few months, providing plants with a slow, steady supply of food. Organic fertilizers, including composted material, will also provide a slow steady supply of fertilizer as it breaks down from its organic form into nutrients that will be readily available to the plants.
Synthetic commercial fertilizers are fast acting and should be applied using caution so as to not burn your plants. Follow the manufactures' recommendations.
Avoid using fertilizer/systemic insecticide combinations as they can cause stunting and deformed leaves, especially when the temperature is above 80 degrees. Also, in Sonoma County roses generally need more regular fertilizing than pest treatments, which means that you are unnecessarily using pesticides with these combinations.
Mulching with any organic materials such as leaves, dried lawn clippings, or compost, will help to conserve water, control weeds, improve soil structure, and keep the roots cool during the summer heat. Mulch can also act as a barrier by preventing disease spores from splashing up onto the plants from the soil. Two to four inches deep, covering all bare soil, yet keeping a couple inches away from the base of the plants is adequate.
Careful pruning can help keep roses healthy and help to prevent disease and pest problems. By pruning out dead, spindly or diseased canes, you can shape the plant and promote flowering, encourage new growth, and increase air circulation to discourage diseases. Remember to check your pruners to be sure that they're sharp! Remove all diseased clippings, fallen leaves and spent flowers. Do not put them in the compost pile.
The amount of water your roses will need depends on the weather, your microclimate and the type of soil you have. Areas that have summer fog will need to do less watering than in areas that do not.
Sandy soils will need to be watered more frequently than clay type soils. Use a moisture meter, trowel, or your fingers, and dig down a few inches to see how wet or dry the soil is. Roses do best with a good, deep watering when needed. It's important to check the soil before the irrigation system goes on, or before you hand water, to get an idea of how often you need to water. You might need to give the roses an extra bit of water during the heat of the summer as compared to late spring, early summer. Unlike some other showy plants that wilt or do poorly during periods of extreme high heat, roses, if given enough water, will flourish and come through just fine.
Managing common rose insects and diseases
If you are shopping for a rose, we heartily recommend that you ask the nursery to suggest varieties that are resistant to - or at least not prone to - the common fungal diseases. This will eliminate later headaches trying to combat them. Once your roses are in the garden, inspect plants regularly to catch any diseases or pests before they become serious. Become familiar with the most common insects and diseases of roses, such as black spot, downy mildew, powdery mildew, rust, aphids and cucumber beetles. If a disease or insect has been a problem on your roses, you may want to use one of the less toxic treatments. Check your local nursery for products such as Kaligreen, Ultrafine oil, and Rose Defense. Because these products prevent, but DO NOT cure diseases, you will need to start spraying before the symptoms become widespread. Be sure to follow the manufactures' directions.
Aphids are generally a problem in spring, and can be squished with your fingers or dislodged with a strong shot of water from the hose nozzle.
Roses are widely available at virtually all nurseries and garden centers. There are two nurseries in Sonoma County that specialize in roses: Garden Valley Ranch, and Petaluma Rose Company, both in Petaluma.