Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
July, 2006
Regional Report

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Not all hybrid tea roses have fragrance, but this 'Tropicana' has a delightfully sweet, fruity scent that I love.

My Own Rose Parade

Now that the growing season is in full swing, we're enjoying our garden to the fullest, especially our lovely roses. Some shrubs require minimal care, but roses need a regular maintenance program for peak performance all summer long.

Many references recommend fertilizing roses once a month, beginning May 1. Since we have such a short growing season here in the Pacific Northwest, I prefer to use a more intensive program. To ensure our plants are growing vigorously so they can produce lots of blooms, I apply fertilizer more frequently than suggested in the reference books.

Fertilizer Regime
Two weeks after the initial May 1 application, I fertilize again, using a water-soluble fertilizer (20-20-20). Each plant is given about one gallon of this solution every two weeks throughout the summer. In between the two-week liquid fertilizer applications we add an organic fertilizer consisting of equal amounts of alfalfa, cottonseed, bone, and fish meal. Two cups of this mixture is worked into the soil around the perimeter of each plant and watered in well. Because roses have lots of feeder roots just below the soil surface, it's important to cultivate with care.

Every month we work 2 tablespoons of Epsom salts into the soil around the base of each plant to encourage basal breaks, and once during the growing season -- usually in mid-July -- we add a supplement of chelated iron for better color. This fertilization schedule is continued through the month of August. Around the first of September we give a final application of 0-20-20 to help harden off the plants and prepare them for winter.

Mulch benefits rose plants in several ways. We use organic mulch because it contributes valuable nutrients to the soil as it breaks down over the season. It also provides a blanket of protection from hot summer sun, slows water evaporation, and discourages weeds. And, if weeds do sprout in organic mulch, they're easy to pull because the roots tend to grow in the loose mulch material rather than anchoring themselves in the soil.

Roses are insatiable drinkers, preferring long drinks to short, skimpy ones. Feeder roots develop on rose plants no matter how they are watered, but long support roots develop only if forced to search deep into the soil for water. We try to give our roses 2 inches of water per week, applying water to the soil, not the foliage. Overhead watering can lead to disease problems, so avoid it whenever possible.

The most common rose diseases in our climate are rust, powdery mildew, and black spot. Powdery mildew is encouraged by warm days and cool nights. It can also occur in overcrowded plantings and in damp, shady gardens where air circulation is poor. The first symptoms are white, powdery mold patches on foliage and stems. Leaves hold their color but can begin to crinkle as the disease progresses.

Rust disease first appears as yellow or orange pustules on the undersides of leaves. As the disease progresses, leaf undersides become covered with masses of rust-colored spores and the upper leaf surfaces show yellow spotting.

Black spots on green foliage are the first sign of black spot disease. Then yellow-fringed rings develop around the black spots. As the disease progresses, whole leaves turn yellow.

We avoid using chemical sprays, preferring to grow our roses organically. We've chosen disease-resistant varieties, and are careful to remove any foliage that shows symptoms of disease to keep problems from spreading. However, many gardeners feel routine spraying is necessary for healthy, vigorous plants. If you're a member of this gardening group, it's very important that you read the label and apply according to label directions. Don't assume that if a little bit is good, a heavier dose is better. Use only products labeled for use on roses, and consider trying some of the milder soap-based fungicides first.

Many insects attack roses, but the most troublesome in my garden are aphids. Aphids are soft-bodied sucking insects, and they appear in great numbers on tender rose growth. I control aphids by rubbing them off between my thumb and forefinger or by hosing them off with a strong stream of water. You can use 2 tablespoons of liquid Ivory dish soap dissolved in 1 gallon of water to control aphids, or apply insecticidal soap or another commercial insecticide labeled for roses.

Most of the serious pruning is done in March, just as buds begin to swell on the canes. In summer you can prune as you remove spent flowers by cutting the flowering shoot down to the first leaf with five leaflets. This will help your roses maintain a neater appearance, rebloom sooner, and produce sturdier stems.

Growing hybrid tea and floribunda roses can be quite labor intensive, but there isn't a plant in my garden that compares to these beauties. I think the effort is worthwhile!

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