Garden Life: Avoid temptation to overwater your garden

By Robb Rosser, Columbian Gardening columnist

Published:

 
photoRobb Rosser

By this time every year, there are a few plants in my garden showing signs of stress from consecutive days of direct sunshine, high temperatures and from lack of rain. In the past, I worried so much about my plants that I would spend whole days dragging a hose around the garden to stave off drought. Nowadays, to keep my garden looking its best, I continue to water through the summer months but I make an effort not to overwater. By that 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 have to rely on an unnatural water supply to merely survive.

In our modified Mediterranean climate, a 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 that evening or at least by the next morning. Pay special attention to the water needs of any trees, shrubs and other plants that have been planted within the past year.

New plants with limited root systems need enough water to get 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. Typically, plants require more frequent watering in their first season in the garden. During very dry, hot weather, I water beds and borders deeply twice a week to keep plants healthy. Watering well means a thorough and systematic soaking of individual plants or planting borders in a specific time frame. A twice-weekly schedule of deep watering is preferable to infrequent overwatering or frequent light watering.

In certain situations, especially valuable plants may be watered individually during stressful climatic periods while the rest of the area is not given any extra irrigation. Various means such as mulching, shade, efficient irrigation methods and hardscape surfaces can be used to make the established landscape, as well as a new landscape, more water efficient. Since we can expect this same drought condition 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 will have faded. Cut the flowering stems back to good foliage for a better overall appearance. Many early summer perennials will take a break after their first flush of bloom and before they flower again when the weather cools in September or October. These will also benefit from cutting back the spent flowering stems. Except for annuals and established, late-season plants that will flower all the way into autumn, much of the color at this time of year is found in mature plant foliage.

Now is the time to monitor watering needs, not to add new plants to beds and borders. In the same breath I have to admit that two weeks ago I sowed a second batch of nasturtium seeds and they are just now emerging in some of the flower beds. Established nasturtiums do not require a lot of water but like any emerging seedling, they need special attention for the first few weeks of growth, at least up until they begin to flower. So I will carry around a watering can with a nozzle that allows a soft, earth-soaking flow for these plants with special needs. I like to plant my nasturtiums late to fill the upcoming gap between summer and fall. Their flowers add a bolt of energy with bright, golden hued yellows, reds and oranges.

My mom was partial to nasturtiums and she liked to remind me that her mother loved them, too. Long after her last visit I can still see my mom's smile in every new nasturtium blossom.

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