Drainage Issues and Solutions

 

In wet seasons like many of us are experiencing right now, the ground can develop several problems resulting from super-saturation. There’s nothing we can do about the rain but there are some wet soil management precautions and procedures.

First and foremost - turn off the sprinkler system! Only turn it on when needed. Better still - unplug it. You may not know how to work the controller. No more water should be needed on your lawn or gardens for a month or so.

Next precaution is to try to stay off the soil. No mechanical work should be done at all. Tilling is especially damaging to any wet soil, but especially harmful to super-saturated soil. When wet soil is dug in or tilled, the tool causes a glazing of the soil and destroys the tilth and that restricts air movement and biological activity in the soil for quite a while. Foot traffic alone causes compaction and damages the soil. Staying on walks and paved surfaces is especially important in vegetable gardens and flower gardens during these wet times.

If you haven’t applied organic fertilizer application, go ahead and get that done. Synthetic fertilizer shouldn’t be put on wet ground, but I never recommend that stuff. It is also a great time to do foliar feeding. Moist plants can accept the nutrients and other goodies best in moist conditions.

There are specific problem spots that don’t drain properly. It’s actually pretty easy to fix but does require some work.

Low, soggy spots in turf can often be fixed by changing the grade of the lawn so the water drains away faster and better from the surface. Completely re-grading the area to change the slope is sometimes necessary, but in many cases the slope can be altered by adding some soil here and there to eliminate the low spots. One of my favorite ways to level out turf areas is to mechanically core-aerate the entire lawn area and then rake the removed cores from the high spots into the low spots. This mini form of cutting and filling works well and doesn’t require planting new grass. If a complete re-grading of the lawn is needed, the existing turf will be destroyed and new grass will have to be planted. So, the other choice is better.

If the low, poorly draining area is around a tree, drainage fixes can be horizontally or vertically and can be done at planting time or after the fact. If drainage problems are a suspicion, perk tests should be run after digging the tree hole. That simply means - fill the tree hole with water and wait until the next day to plant. If the water hasn’t substantially drained away, drainage solutions need to be added. One method is to bore hole from the bottom of the tree hole down into a different soil strata that hopefully has better drainage. For existing trees, the hole can be bored from the soil surface down to the drainable soil or rock.

The other method to dig a ditch from the tree hole out to a lower point on the site. As the drawing from my book, Texas Gardening - the Natural Way, shows the ditch can be dug, a drainage pipe installed and soil used to fill the rest of the ditch back in. However, I think it is much better to fill the entire ditch with gravel. It just works better. A drainage pipe is not nearly as important in this case and the ditch functions as a water inlet for the entire length of the ditch. Multiple trees can be connected together by similar ditches if necessary. The best gravel to use is crushed limestone that has irregular shapes. Smooth pebble gravel does not work as well. Lava gravel works even better and has additional benefits, but costs quite a bit more.

For trees that have had root flare exposure done and the depression around the base holds water during and after rains, don’t worry in most cases. Remember that before the soil and mulch were removed, the flare stayed wet all the time. Now it just stays wet until the water percolates away or evaporates. If you think the water is staying too long, the same drainage ditch as explained above can be installed. If your garden soil stays moist most of the time, even during normal rainfall weather, there are plants that can take the moist environments better than others.

Some of my favorite plants for wet soil include the following:

Groundcovers:

The above list should be useful but very few plants will grow at their full potential when soil is constantly saturated; however, some trees, shrubs and ground covers are more tolerant of wet sites than others. It is the lack of oxygen in wet soil that damages plants. Many trees and shrubs can survive under wet conditions but will usually grow poorly. They will be more susceptible to insect pests and diseases also.