Certainly, when plants are ailing, the first suspect is water. Flowers, shrubs, and trees all look less than healthy with either too much or too little water.
It’s easy to tell if the problem is too much water — just dig the soil around your plant down an inch or two and touch it to gauge how moist it is. If the soil is wet and your plant is looking peaked, let it dry out a bit before watering it the next time. If the soil is dry, your plant would probably benefit from a nice slow, deep soaking.
A moisture meter, found at most nurseries and hardware stores, is another reliable way of gauging whether a plant needs water.
For years, I waited until my landscape showed signs of stress before looking into the water needs of my plants. I wasted a lot of time, effort and money with my “only the hardy will survive” attitude toward gardening.
To make your gardening adventures more successful, group plants by water needs, give them the appropriate amount of water and water them infrequently, to allow the water to penetrate the root zone and promote healthy root growth.
Using an arbitrary circumference of 36 inches for a plant’s root zone and thinking of the summer season, the plant types listed below will need water applied weekly over their entire root zone in the amounts noted:
• High water-use plants, such as hydrangeas, cool-season grasses and redwood, birch and willow trees, should need between 4.67 and 5.84 gallons of water.
• Medium water-use plants, such as agapanthus, marguerite, camellia, bear’s breeches, citrus trees and Japanese maples, should need between 2.34 and 3.50 gallons of water each week.
• Low water-use plants — think California natives — should be happy with water in the range of 0.58 to 1.75 gallons per week.
Larger and smaller plants will use different amounts of water, of course, and there is nothing like good common sense and your fingers or a water meter to judge whether your plants need a little extra water based on the temperatures outside.
•The Green Thumb is a column by Tracy’s master gardeners. University of California certified master gardeners are available to answer gardening questions from 9 a.m. to noon Tuesdays, Wednesdays, and Thursdays at 953-6112 or firstname.lastname@example.org.