August 5, 2010 in Washington Voices

Water, fertilizer needed to get roses winter ready

Pat Munts
 

Now that August has begun, it’s time to get roses ready for the fall and winter.

Keep plants well watered. Check how deep the water is getting by digging a small hole in the rose bed a few hours after a watering and measure how deep the water soaked the soil. If its only three to four inches, increase your watering enough to wet the soil six to eight inches down. Add two to three inches of mulch to the bed to help keep moisture in. Untreated grass clippings, shredded pine needles or leaves or compost are all readily available for free or a nominal cost. As you mulch for moisture, stockpile more mulch nearby so it is easier to cover the tea roses in late October.

The last fertilization for roses in the Inland Northwest should be about a month before the first frost date. Given that is Sept. 15, apply fertilizer by mid-August. This will give the plant time to put on new growth for fall blooms but have enough time to harden that growth off before we get hard frosts. A lot of people lost established roses this spring because the plants were still growing vigorously when we got the cold snap last October. Roses are heavy feeders so use a good quality rose food. Water well before you fertilize as roses will pull fertilizers up quickly and there needs to be enough water in the soil to dilute it.

Aphids and other bugs had a field day in the cool weather and will still be hanging around. They will appear as pale green to tan bugs that feed on the new growth of the rose. If they are present in enough numbers, the leaves will be twisted and deformed and ants may be present. They actually tend the aphids to collect the honeydew.

Often a hard blast of water from a hose will dislodge enough aphids to reduce the damage. If you can live with a few bugs, watch for predator bugs like lady bugs and lace wings. They will follow an aphid infestation and clear them out quickly. If you feel you need to spray, try an insecticidal soap first rather than harsh chemicals. Any spray however will kill both good and bad bugs.

Most roses grown today have been bred for better disease resistance than plants developed even 10 years ago. In fact the All America Rose Selections, which conducts trials of new breeds of roses, requires that plants not be treated for diseases in their test gardens around the country.

Use cultural methods to control diseases. If one of your plants is prone to disease, consider replacing it. Make sure roses get lots of sun and good air circulation. Run soaker hoses through the beds to keep water off the leaves where it can spread disease spores. If you need to spray use an organic fungicide like neem oil or conventional nonorganic fungicides.

Pat Munts is a Master Gardener who has gardened the same acre in Spokane Valley for 30 years. She can be reached by e-mail at pat@inlandnwgardening .com.

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