Garden Life: Find right balance for summer watering

By Robb Rosser, Columbian Gardening columnist

Published:

 
photoRobb Rosser

In mid- to late summer, I always find a few plants in my garden showing signs of stress from multiple days of continuous sunshine and the return of summer drought. Since I added a few plants to the garden this spring, I will continue to water through the summer months to keep my garden looking its best. However, for the long-term health and care of my garden, I try not to overwater in any season, including summer.

By this, I mean that I give my planting beds and flowering borders enough water to thrive in the summer months but not so much that the plants come to rely on an unnatural, overabundant water schedule merely to survive. I have learned from mentors and from experience, that it is best to water deeply, less frequently. With the exception of pots, planters and seasonal displays, I cut back on a daily summer watering schedule for most established garden plants.

In our modified Mediterranean climate, the cycle of wet months and dry months is the normal state of things. One of the advantages of a climate with continuous winter rain is that it helps plants prepare to withstand a period of summer drought. Even so, during a series of hot, dry days, we can expect our perennial plants in full sun to display a slight droop by late afternoon. Healthy plants will return to their rigid stature later in the evening or at least by the next morning.

I wasn't sure that summer would ever come this year. Now that it has arrived, it's important to pay special attention to the water needs of any trees, shrubs and other plants that were planted within the last eighteen months. New plants with limited root systems need enough water to become established. This is most important in the first season after planting but can remain critical into the second and sometimes even the third year if weather conditions have been poor and root expansion is slow.

Frequent watering may be necessary if this is the plant's first season in the garden. On the other hand, one complete watering each week should be enough to stave off plant damage in long-established hardy shrubs, trees and groundcovers. Deep, thorough soaking of individual plants or planting beds on a regular basis is the best way to irrigate. This is preferable to infrequent heavy watering or frequent light watering.

There are a few ways to make an established landscape, as well as a new landscape, more water efficient. Mulching, planting to create shade and installing an efficient watering system are important. Since we can expect these drought conditions every year in our Northwest gardens, it makes sense to establish the groundwork for an efficient system as soon as possible.

By this time of year, even the longest-blooming, late spring plants have faded from the garden. Cut the flowering stems of these plants back to good foliage for a better overall appearance. Many early summer perennials take a break after their first flush of bloom. These plants benefit from cutting back the spent flower stems. If you do so, they may rebloom when weather cools in September and October. In certain situations, valuable plants should be watered individually when they show signs of stress.

As much as I enjoy adding new plants to the garden, now is the time to monitor watering needs, not to put in new plants. In the same breath, I have to admit that two weeks ago I sowed a second batch of nasturtium seeds. They are just now emerging in some of the flower beds. Nasturtiums do not require a lot of water but any emerging seedlings need special attention for the first few weeks. Until they begin to flower, I will carry around a watering can with a nozzle that allows a soft, earth-soaking flow for these special-need plants.

I think it's important to keep in mind that we do not want to get in the habit of overwatering. What I am trying to encourage is the awareness that planting beds and flowering borders need enough water to thrive in the summer months but not so much that the plants have to rely on a completely unnatural water schedule to merely survive. Potted plants are the exception. Garden plants watered deeply but less frequently will have a deeper root system than those watered more often. Therefore, they will survive better in our annual period of drought.

Robb Rosser is a WSU-certified master gardener. Reach him at Write2Robb@aol.com.