Temperatures affect pruning and feeding of roses

The recent showers were a nice respite from the high temperatures and dry windy weather, but they are misleading: the moisture is only temporary and doesn't sink very deeply.

The outlook is for high temps to return and maybe even triple digits.

Last month I gave illustrations and descriptions for mid-season pruning with a suggested timeline for pruning and restarting your feeding program. What may not have been clear is that this is a light pruning, and must be carefully calibrated with the weather conditions.

Specifically, when temps remain in the 90+ range, you must take care to not remove too much foliage because this can over expose canes to the fierce sun and sunburn them. This can damage or kill otherwise healthy canes or even the entire plant. If planning to have roses for a special occasion later this year, it will take six- to eight-weeks from this pruning and feeding.

After pruning, restart your feeding program. Make sure the plants are watered the day before. I recommend organic types and alternating with fish emulsions. Use a fertilizer that contains greater percentage of (P) phosphate in relation to (N) nitrogen and (K) potassium. This will assist the resistance to any stress and encourage stronger root systems.

If temperatures are in the 90s or above, and you do not use organic, hold off fertilizing until weather cools. If you use a fertilizer that is first dissolved in water, apply it right over the bush from top to bottom. A hybrid tea would need about two gallons of solution and should be watered in after a couple of days.

If you use a dry granular product, be sure to scratch it into the soil surface around the base of the plant, and then water it in. Apply in the concentration recommended on label; if growing in pots, use half the recommended amount, but apply it more frequently. Repeat your applications every two weeks.

When temperatures continue to be in the 90's, it is necessary to ensure plants receive adequate water to stay hydrated. It takes only a few days in these temperatures without sufficient water for a bush to become seriously stressed and even damaged. Because of California's restrictions of water use, I suggest that with three gallons of water per Hybrid Tea (HT) twice per week, a HT rose bush can survive.

A layer of four inches of mulch will greatly reduce evaporation of soil moisture. This year the soil dries out more quickly than in previous years due to less water being applied as in previous years and, in general, the dryer soil environment.

With potted roses, this is even more critical. Assess conditions every morning. Look for wilted or dry, crispy foliage. If you discover it soon enough, dousing with plenty of water may save the plant. If you wait to inspect until the afternoon or evening, it may be too late or you might not get a good assessment of the plant's condition: After a hot day, most plants can appear wilted while still receiving sufficient hydration.

Also inspect your irrigation system to make sure it is delivering enough water, isn't clogged, and isn't over watering—all problems that come with age in drip irrigation systems. If an emitter is delivering much more or much less water than others on the line, it can change the system pressure and affect the other emitters. The simple solution: Replace it!

If a clay pot is used, more water is needed as the clay will absorb moisture from the potting soil and evaporate through the porous clay material. Plastic pots are better as they will not absorb moisture from the soil.

Another possible problem with potted plants is the soil can pull away from the sides of the pot and water will just run through and out the drain holes in the bottom. This problem can be corrected by pressing the soil back against the inside sides of the pot when the soil is wet.

If you haven't mulched recently, estimate the amount of composted mulch you'll need in order to cover your garden beds four inches deep and plan to buy it for this coming winter or spring. An area ten-feet by five-feet will require four to five cubic yards of mulch.

A common problem when hot, dry, dusty conditions prevail is spider mites. This topic was covered in a previous care column which you can find at www.thevillagenews.com.