As the temperatures rise and hot winds blow, those of you who are still fairly new to gardening may be asking this question:
How often should I water my garden?
The simple answer:
As often as it needs it.
First off, before we get into specifics, let’s take a look at what we are trying to accomplish by watering. Plants use water in their metabolic processes, and they also rely on soil minerals suspended in a water solution to provide for their nutritional needs. For this reason, plants must always be able to put their roots into a source of water, or their health and produce quality suffers.
However, there can also be to much of a good thing. Obviously, when the soil is completely saturated, the water displaces the air component of the soil and the plant roots drown. But there are other, more subtle consequences to a soil that is consistently kept overly moist. The plants grow shallow root systems that are highly susceptible to the onset of drought. Furthermore, the nutritional content of the produce is diluted and the flavor is diminished.
So while plants must always have enough moisture to maintain their biological processes, it does not hurt them to have to work for it a little. As long as a reservoir of moisture is preserved below the roots and the soil texture is conducive to healthy conditions, capillary action will wick moisture steadily upwards toward the roots, while the roots themselves will penetrate steadily deeper. The result is a flourishing root system that can sustain a plant through extended dry spells.
Of course, plants vary in their ability to grow deep. Seeds must have moisture right at the surface of the soil for germination, and freshly sprouted seedlings need water at the surface, as well. Even mature plants of some species, such as lettuce, cannot penetrate the soil to any considerable depth. But in general plants benefit from a deeper and deeper water supply as they grow.
The Leaf Test
The way that you become a green thumb is by working with plants until your fingers are stained. By the same token, the way that you learn how often a garden should be watered is by observing your plants.
The leaves of your garden and orchard plants can tell you a great deal about how the plants themselves are feeling. That vibrant, glossy green of new leaves in spring tells you that the plants are spunky and growing fast. When the leaves look dull and dusty, maybe with a little bit of curl to the edges, the plants are suffering from dehydration. If the leaves have already begun to wilt, the plant is too stressed.
There is no better way to gauge how often the garden should be watered than by reading the leaves. It is 100% reliable and will enable you to catch problems early. This method does require experience and close observation, however.
The Finger Test
So for those of you who are still trying to figure out what a thirsty plant looks like, there is another, simpler way to get a fairly good idea of when the garden needs to be watered. Take a look at the soil. Is it moist on top? If not, poke a finger down beside a plant. Do you feel any moisture further down? A thin layer of dry soil on the surface usually won’t hurt anything, and in fact allowing the surface to dry out between waterings can help prevent fungal diseases, but there must be moisture down at the level of the roots.
This soil moisture test is useful, but not quite as reliable as the leaf test above. Again, different plants have roots at different levels. A lettuce plant or a freshly germinated seedling of any species has a very shallow root system and needs access to water very close to the surface. A fruit tree or even a tomato, on the other hand, can seek water deep enough below the ground that the finger test won’t really avail you anything. For most garden plants, however, this test works fairly well.
A Word on Scheduling
Finally, a word on scheduling watering times. A rigid watering schedule can be a hindrance in the garden. Although it’s a good idea to have a time for watering planned into your daily routine so that you don’t forget and miss a day, for best results you must learn to tailor your schedule to the needs of your plants. Suppose you plan to water certain plants daily, others every other day, and still others weekly. Can you adjust to meet changing weather conditions? If a heavy rain falls, you will want to skip watering that day. On the other hand, if the weather is exceptionally hot and dry, you probably will need to water your garden more frequently to keep it alive.
That said, a little bit of scheduling can help you avoid overwatering, as well. In general, most established plants should be watered no more than twice a week. In fact, a deep, thorough soaking once a week is better for all but the most finicky plants. Many perennial fruits and vegetables, such as asparagus and bramble fruits, can be watered closer to every three to four weeks, depending on the weather (strawberries will require much more frequent watering). Watering of established fruit trees should be kept to a bare minimum to prevent shallow root growth.
But the important thing is to learn to read the plants. They can tell you when they’re thirsty.