April through June is the peak of the rose bloom. Opulent flowers cascade from or crown shrub roses and climbers, each a masterpiece of design and color. Plain, fat buds transform into astonishingly beautiful multipetaled or hued flowers of satin orange, warm apricot, deepest crimson, teacup pink, translucent white and every color in between.
Roses are among the most popular and commonly grown plants in our gardens. And yet, after peak bloom, many shrubs fail to perform well and are not attractive. Fungal diseases like black spot and rust may decimate leaves, or the whole plant may assume a scraggly and pale appearance from a lack of nitrogen. Shoots from the rootstalk can dominate the plant and eventually weaken it so much it dies. How do we grow handsome, healthy roses that are attractive even when out of peak bloom?
Jan Tolmasoff at the Russian River Rose Company in Healdsburg (russian-river-rose.com) grows and sells some of the healthiest roses in our area. Her garden and nursery is open each weekend in April and May or by appointment. The magnificent rose garden surrounds her vintage Spanish style house, and is a perfect place to see a grand and fragrant display of roses grown to perfection. Each rose variety is trailed for three years to see how it performs in the climate and soils of our area. Anything prone to disease or lacking in vigor is discarded. She has much practical advice for growing healthy roses.
Select disease-resistant varieties. A number of popular varieties from the 1950s or 1960s like “Tropicana,” “Mr. Lincoln” and “Sterling Silver” are actually disease prone. ‘Moonstone’ and ‘Oklahoma’ are good alternatives. Tolmasoff finds the David Austin Roses variable, especially the red group, but says the variety ‘Falstaff’ is very vigorous. Some strong varieties suitable for the end of vine rows are ‘Livin’ Easy’ and ‘Julia Child.’
Climbers that really perform are ‘Fourth of July’ ‘Westerland’ and ‘Colette.’
Tolmasoff has a section of the garden for shade-tolerant roses, many of which are Hybrid Musks.
Cut rootstalk suckers below soil level. Chose own-root roses if available.
To help prevent fungal diseases, space plants so they have adequate light and air circulation.
Dig a big hole at least 18 inches wide by 18 inches deep. The harder it is to dig, the bigger the hole should be. Put 1 to 2 cups of gypsum in the bottom of the hole and mix in to help break up clay soils and for calcium. Don’t use Epsom salt as it is high in magnesium — a problem nutrient in many of our soils. Make sure the soil surfaces in the hole are roughed up to avoid creating a barrier to root growth.
Mix the native soil with at least ⅓ compost. Make sure compost is mature, not hot. Some good sources are Sonoma Compost, Pt. Reyes Compost Company, Grab N’ Grow and Soil’s Plus.
Set the plant in the hole so that the soil in the pot will be at ground level.
Water well to soak the soil.
Mulch four to six inches deep with a nutritious mulch. It can be more of the compost that was put in the planting hole, or composted green waste (Clean Green Organic Compost from Grab N’ Grow or Vineyard Mulch from Sonoma Compost). Don’t use wood chips, which rob nitrogen from the soil as they break down.