How Much Water Does a Rose Need for Good Health?
From Q & A with Dr. Tommy
By Dr. Tommy Cairns

Taken from The Rose Reporter, April 1999
Tinseltown Rose Society
Luis T. Desamero, Editor
Reprinted in The Charleston Rose, May 1999

How much water does a rose need for good health?

With the lack of measurable rainfall during the summer months, the emphasis on growing roses switches to providing an ample supply of water to the root system. It is fairly obvious that as the temperatures climb, the roses transpire more rapidly via their foliage and so their needs are far greater than in the cooler months of early spring. Deep watering as often as three times per week is recommended during the hot summer months for a number of reasons.

An ample supply of water must be delivered to each bush to allow the water to penetrate at least down to the base of the root system, usually two to three feet deep. Water moves through the soil like drawing a window shade down a window. The key is to provide sufficient water for your soil type to allow this required deep penetration.

If the soil type is sandy loam with good drainage, then a delivery of about three gallons should suffice. If the soil type is clay, then about six gallons will be needed to allow deep penetration since clay soils tend to hold up penetration because of the many small spaces between which trap the water and prevent its downward course to the deeper root system.

If insufficient water is supplied to the plant, then only the topmost feeder roots receive water and the lower root system may be denied an ample supply of water. If too little water is supplied, then the plants will tend to show signs of wilting or display a limp appearance. On the other hand, too much watering will flood the soil (as easily done in clay soils) and the foliage will go yellow and die.

Mastering the right amount of water to be delivered to each plant is not that difficult to gauge. If temperatures are above 80 degrees F during the day for more than several days, then your watering schedule should be three times a week. If daytime temperatures soar above 90 degrees F, then watering every other day during the summer will be mandatory.

For container grown roses, watering every other day during the summer is strongly recommended whatever the temperature since good drainage is guaranteed and soil flooding is impossible. Besides, the root system in the container itself is subject to a higher temperature than that normally experienced by the root system in the ground itself.

On the subject of the various automatic watering systems, roses do not grow well when single or dual point drip systems are employed. The main reason for this lack of growth is that the moisture tends to remain localized around the bud union and rarely allows the moisture to travel any great distances from the point of the drip.

Some gardeners have realized this cause and effect and have adopted multi-drip points arranged in a circle around the base of the bush. While this arrangement is so much better than a single drip source, many of the same concerns about penetration still exist. For ensured vigor the water applied must move down through the soil to the lower root structure.

The best possible method is a single application of several gallons within a few minutes delivered by hand or by an automatic high volume sprinkler system either overhead or ground level.