A. Water them when they need it and give them as much as they need. Now that is a very simple answer to a question that can be quite complex. Nevertheless it is a concept which the home gardener should not forget. Mature citrus trees require about 50 inches of water per year. During a normal year, Galveston County should receive almost that much, so it would seem that we need to supplement very little. The fine print, however, causes us to look at things a little differently. Soil acts like a bank account, holding water for our trees. Just like a bank account, as water is withdrawn, it must be replenished. The trick is to know when the bank account is getting low so that it can be replenished before it is overdrawn. Then, unlike a bank account, the soil around a citrus tree can contain too much water, especially a newly planted tree. If the soil is saturated for long periods of time, citrus trees can develop a condition commonly called "foot rot", a fungal disease that attacks the roots, especially the roots of younger trees, and can be fatal to the tree. |
|
Heavy clay soils, such as our Galveston County "gumbo", take in water and nutrients slowly but retain it rather well. Sandy soils, on the other hand, take water almost as fast as we can apply it, but the water as well as nutrients pass through rather quickly. The addition of organic material such as shredded pine bark, compost, mulch and other soil amendments, can dramatically increase the water holding capacity of the soil while at the same time allowing for fairly rapid intake capacity.
So, if we are to know when and how much to water citrus trees, we need to know how mature the trees are, what kind of soil we have, how much rain we have had and whether the rain was a slow drizzle, a hard rain, or something in between. A hard rain on heavy clay soil will not refill the soil bank unless it is of long duration, most of it will become runoff.
Let me suggest three different things that might help you decide when to irrigate and how much. Put a couple of empty cans or cake pans near your trees in an open area so that they are exposed to the wind, rain and sun. Cover them with wire mesh to prevent birds from drinking out of them. Then, after a heavy rain or thorough irrigation, add water to the cans until the water is two inches deep. Between mid-April and mid-September, irrigate to the equivalent of a 1-½ inch rain when the cans are completely dry (five gallons per square yard is about 1" of water). When you are finished with irrigation, refill the cans with two inches of water and repeat the procedure. From mid-September through mid-April, only irrigate to the equivalent of one inch of water when the cans are empty. The second thing you can do is insert your finger into the soil past the first inch or two. When you remove your finger, notice whether it feels cool or warm. If it feels cool, the soil still has enough water. If it feels warm, the soil probably can stand to be irrigated. The third thing you can do is purchase a soil moisture meter from your local garden supplier. The meters are not very expensive and the expense might well buy you a good nights sleep. Remember, on our heavy soil, irrigation should be applied at a slow rate so it doesn't just run off.