Rose care includes checking irrigation system

Frank Brines ARS Master Consulting Rosarian

It looks like we are back to a period of more normal temperatures for this time of year. Santa Ana winds could show up anytime now, so homeowners should make sure to check the irrigation system after summer conditions ease.

Roses should be actively recovering from the light fall pruning. Last month, I gave illustrations and descriptions for midseason pruning with a suggested time line for pruning and restarting a 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 temperatures remain in the 90-plus range, you must take care to not remove too much foliage because it can overexpose canes to the fierce sun and sunburn them. Sunburn can damage or kill otherwise healthy canes or even the entire plant.

If you’re planning to have roses for a special occasion later this year, it will take hybrid teas six to eight weeks from this pruning and feeding to produce them. Floribundas and miniatures will take a little less time. This cycle of bloom is the second best of the season and is necessary to achieve maximum potential. Exhibitors are pruning and planning in order to time blooms for the fall shows in the area and in Arizona. The Orange County Rose Society fall show is Oct. 28.

After pruning restart a 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 phosphate in relation to nitrogen and potassium. This ratio will assist the resistance to any stress and encourage stronger root systems. If temperatures are in 90s or above and you do not use organic products, hold off fertilizing until the 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 2 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 to drip line and 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 the applications every two weeks. The last date for fertilizing is 30 days before the frost date, in this area that is around mid-November.

When temperatures continue to be in the 90s, 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. I suggest that with 3 gallons of water per hybrid tea twice per week, the rose bush can survive. A layer of 4 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 issue 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, it isn’t clogged and it isn't overwatering – 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 is to 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. Most people use black plastic pots as containers, these pots tend to heat the soil in them from the sunshine, giving an added reason to check these plants frequently for soil pulled away from the sides and damaged roots from the heat. Ideally these pots should be placed in another larger one for some insulation.

It’s not too early to start thinking about which roses you will remove and their replacements. Very few suppliers have catalogs any longer, but most should have online catalogs. If you haven’t mulched recently, estimate the amount of composted mulch you’ll need in order to cover your garden beds 4 inches deep and plan to buy it for this coming winter or spring. An area 10 feet by 5 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 on the newsletter at www.TemeculaValleyRoseSociety.org newsletter; look for the care section for September 2013.

Amercian Rose, a valuable bimonthly magazine covering rose topics, is published by the American Rose Society. Visit www.ARS.org for more information on obtaining it.

When you have a moment to spare, feel the need to get away or when the day cools down, take your favorite beverage, a picnic basket and visit our local one-of-a-kind Rose Haven Heritage Garden, 30592 Jedediah Smith Road, in Temecula. Also, visit the website at www.TemeculaValleyRoseSociety.org and spread the joy of roses.