The most important thing to remember when addressing your plants’ water needs is to apply water deeply and infrequently. How deep and frequent depends on site, exposure, soil type and plant species, but there are some general guidelines to help grow healthier plants.
Even Mother Nature has overwatered some plants this summer, and the result is shallow, poorly developed root systems. When roots stay in the soil surface instead of growing down deep into the soil, they cannot reach deeper water reserves and have trouble supporting the rest of the plant when temperatures rise. When plants lack the water they need, leaves wilt, turn yellow and sometimes drop from the plant.
With any plants, remember to apply water to the roots instead of the plant itself. Wet leaves and stems are a great environment for disease-causing fungi and bacteria. Always apply water early in the morning to prevent water loss from wind and evaporation and to allow the plants to dry during the day. If you must water in the evening, try to finish at least an hour before dusk so that plant tissues dry somewhat before dark.
Check soil moisture prior to watering instead of using a set schedule. Use a trowel, knife, hollow soil probe, or even a long screwdriver to look at the soil a few inches below the surface, and wait to water until the soil is dry below the surface layer.
Wood chips, straw, shredded leaves and other mulches made from plant materials reduce soil water loss and the need for frequent watering.
Container plantings are often the neediest plants and in most situations should be watered every day or every other day. Use containers with a drainage hole(s) in the bottom and apply water until moisture seeps from the hole. Patios, sidewalks and walls reflect sunlight onto plants and trigger more water loss, so containers near these things may need even more frequent watering.
When watering young trees, deep and infrequent application is especially important. Let water run very slowly (trickling from the hose or rain barrel) over the roots of the tree for a period of a few hours. Shorten the amount of time if water runs off because of slope or soil type.
Another method is to drill holes (one-eighth inch diameter or similar size) in the bottom of a 5 gallon bucket, fill the bucket with water, and set it over the young trees’ roots.
For mature trees, use a sprinkler or soaker hose to water a large area under the tree. A good rule is to apply water all the way to the drip line, which is the area below the outermost circumference of the tree’s branches (think of rainfall and how the rain “drips” through the tree’s leaves).
Large trees need water over extended dry periods even though they may not show wilting and stress as quickly as smaller plants.
In the vegetable garden and around plants prone to fungal diseases such as roses, soaker hoses or drip hoses are the best option for applying a small amount of water over a long period of time.
Remember that plants suffering from over watering exhibit the same symptoms as plants that are under watered. Excess water damages roots thus limiting the amount the plant can absorb.
— Jennifer Smith is the Douglas County Extension Agent–Horticulture for K-State Research and Extension. Contact her or an Extension Master Gardener with your garden questions at 843-7058 or firstname.lastname@example.org.