Rose Tips by Al Karsten
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August 2002 Rose Tips
Even though we think of August as a high point of summer, it is time to fertilize the roses for the third and final time this growing season. Roses should be fertilized during August, but NO LATER than this weekend (August 16-18) as roses need to start their dormancy period.
Dig a shallow circular trench around each rose bush and apply an 8 oz. cup of 13-13-13 fertilizer. Water in thoroughly. When you have completed your fertilizing and watering go back and water again - one gallon per bush. Cover the shallow trench by hand.
Fertilize miniature roses no more than a 4 oz. cup of 13-13-13. Always water thoroughly. They do not require as much fertilizer and you do not want to burn the roots. When you apply 13-13-13 fertilizer you get a rapid availability of nutrients to the roots of your roses. If your roses show foliage as pale green color, weak spindly stems, small flowers--starting at the bottom of the plant, the rose bush may be deficient in nitrogen. Nitrogen, the first number, is necessary for plant cell growth and plant respiration (breathing).
If your rose bush looked healthy last week and you suddenly noticed a cane with wilted leaves, in all probability it is a canker disease. If the cane is dark in color (as opposed to green) you should cut the canker cane out from the rose bush. Go down to the part of the cane where it is green to make the cut. In some cases this could be all the way to the soil area. Canker is usually caused by damage to a rose cane.
At this time of the year you may have yellow leaves on your rose bushes. This could be from humid conditions in our area or if yellow leaves are at the bottom of the bush, it may just be older leaves. If the yellow leaves have Blackspot you need to spray weekly with a fungicide. Pick all yellow leaves on the rose bushes and any in the soil around the bush. With good watering practice, new leaves will soon appear.
The heat has an important part in your spray program. Do not spray when the expected daytime high temperature is over 90°F. Discontinue spraying until the temperatures are below 85°F. From 85 to 90°F cut your spray application in half (If the directions on the container indicate one tablespoon per gallon, use only 1/2 tablespoon). Remember to water roses prior to spraying if moisture is lacking. The roots need the water so that the chemicals do not burn the leaves.
Even though you should not apply granular fertilizer after mid-August, you may add a soluble fertilizer such as Miracle-Gro, K-Gro (K-Mart) or Rapid-Gro. One tablespoon per gallon. This can be added with your fungicide and insecticide spray. All three may be combined in a pump sprayer for spraying. Do not save extra spray. Apply to plants you have noticed mildew or insect damage.
Remember that using chemicals has a down side. If you are gardening for butterflies, they will not approach where chemicals have been applied.
Check your roses in August for spider mites on the lower leaves of the rose bushes. The leaves will be a lighter color as the mites suck the juices. With your garden hose, or water wand and forceful water, spray under the leaves from the bottom to half way up the rose bush. Spider mites are usually not at the top of the bush. Spray again in three days. Wait three days and spray again. During this period you should have disrupted their breeding cycle. Check in a week to see if mites have returned. If they have, repeat the above procedure. Generally by early September spider mites have disappeared, unless we have very warm days.
Warm days in late August and September, with cool nights, can encourage mildew. When the weather permits, continue your weekly fungicide and insecticide applications and soluble fertilizer. You should be able to avoid the Blackspot and mildew problems.
August is usually hot and dry. If we do not get sufficient moisture water the roses at least one inch per bush per week. Two inches is better. Continue to water roses until the middle of October if we are lacking rainfall.
Continue to remove
faded blooms. Faded blooms should be cut ¼ inch above the
highest fifth petal leaf. A new "eye" will be forming at the
axial of the fifth leaf which produces the new rose cane. Discontinue
deadheading (cutting off) faded blooms by the second week in
September. This is another process of hardening off the rose bush for
winter. It is all right to cut roses to bring into your home or to
share with others but you need to leave some of the blooms on the rose
bush. When the petals fall from the bloom, it is then a rose hip
which should remain on the bush. It is OK to cut a few hips for
During the hot days of August, mulching the rose bed is very helpful. A two to three inch layer of compost, DRY grass clippings, or dry cow manure. Adding dry mulch discourages weeds and conserves water in the soil.
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