Proper Watering is Key

A split-second decision has lasting impact
April 15, 2008
Terry J. Bourgeois
April 17, 2008

Now that the weather has heated up during the first week or so in May, proper watering of your lawn, landscape, and containers is critical to insure success. Let’s look at what you should be doing to maintain the health and vigor of several types of plants in your landscape.

According to LSU AgCenter horticulturalist Dan Gill, the first summer after planting is the most critical time for newly planted trees, and proper watering plays a major role in whether or not they survive – or how well they survive. Here are some effective watering techniques for trees.

One good method is to turn a hose on trickle, lay the end on top of the ground within 6 inches of the trunk of the tree and let the water trickle for about 20 minutes to 30 minutes. Or build a 4-inch high levee out of soil around the edge of the area dug up to plant the tree. Fill this area with water and let it slowly seep into the root zone.

I’ve found one of the best methods is to use a heated metal skewer or ice pick to pierce five to 10 holes through the bottom of a 5-gallon paint bucket or similar container. Make all the holes on one side. Place the bucket next to the tree trunk with the holes closest to the trunk. Fill up the container, and the water will slowly seep through the holes, providing excellent irrigation. If you want, you can spray paint the outside of the bucket dark green to make it less noticeable.

Use any of these techniques during hot weather whenever seven to 10 days pass without substantial rainfall. Continue to water twice a week until a good rain occurs. Drought-stressed trees may experience wilting, leaf drop, yellow or brown leaves, scorched leaf edges or even death.

Newly planted shrubs will need to be monitored more carefully and watered more frequently than established shrubs. Water with soaker hoses or sprinklers left on long enough for the water to penetrate at least 4 to 6 inches into the soil.

Keep in mind that all of a newly planted shrub’s roots are in a small area – about the size of the pot the shrub was growing in before planting. This is especially true for shrubs planted after March, since they have had little time to grow roots into the surrounding soil. A shrub can use up all the water in its root ball and become drought stressed even though the soil in the bed outside of the root ball is moist. So when checking the soil moisture in the bed, always be sure to stick your fingers right around the shrubs themselves.

Now is a great time to lay sod to install a new lawn or repair an established one. But keep in mind that newly laid sod needs special attention to watering. Water newly laid sod for about 15 to 20 minutes every day for the first seven to 10 days. Then water for about 30 minutes every other day for another seven to 10 days. After that, irrigate the lawn thoroughly once or twice a week, as needed, to encourage the roots to grow deep into the soil.

Do not water every day for more than 10 days or you may encourage fungus diseases. And, of course, there is no need to water if adequate rainfall occurs.

Water seeded areas (vegetable seeds, flower seeds or lawn seeds) lightly by hand or with sprinklers every day until the seeds germinate and start to grow. It is critical for the soil to stay moist during germination. Once the seeds come up, water more thoroughly less often to encourage the roots to grow deep into the soil. As the seedlings become established, water normally as needed.

Watering plants in containers outside is a constant job during the summer. It is typical to water every day, even twice a day, when weather is hot and dry. Keep this in mind when considering how many outside container plants you can maintain. How often you have to water container plants is influenced by temperature, pot size, the type of potting mix, the drought tolerance of a plant, whether a plant is in sun or shade and how pot bound a plant is. Plants need to be watered more frequently when it is hot, if the containers are small, if a light potting mix is used, when plants are in a sunny location and when plants are pot-bound. In addition, clay pots tend to dry out faster than plastic or glazed ceramic pots.

To reduce the amount of watering you have to do, use larger rather than smaller pots, choose a potting mix that retains more water (it must still be fast draining, however), repot pot-bound plants into larger containers, use plastic pots and, if practical, move the plants into somewhat shadier conditions. Potting mixes will retain more water with the addition of hydrophilic polymers. These gelatin-like particles hold large amounts of water without creating a waterlogged soil condition. Look for these polymer products or potting mixes that contain them where garden supplies are sold.

Vegetable Gardening Update

You can still plant sweet corn in your vegetable garden through May 15th. Varieties with different maturity dates, early, midseason and late, can be planted on the same date and provide a harvest of sweet corn for an extended period. Normal or sugary (su) sweet corn varieties recommended for Louisiana are:

* Early-maturing: Seneca Horizon and Aztec.

* Mid-season: Bonanza, Merit and Funks Sweet G90 (bi-color).

* Late-maturing: Silver Queen (white), NK199, Iochief (AAS), Gold Queen and Golden Cross Bantam.

You should plant sweet corn in a block of several short rows side by side rather than in one or two long rows. By planting in blocks, you allow the pollen to move from one plant to another more surely. This helps to ensure pollination of each silk. A fully pollinated ear should fill out completely. Each silk is connected to one kernel of corn, and pollen from the tassels must be deposited on each silk to ensure fertilization of each kernel.

Plant the seed about 1 inch deep and thin plants about 10 to 12 inches apart in rows. Rows should be at least 36 inches apart. Two ounces of seed will be sufficient to plant 100 feet of row. Very sugary varieties or the super sweets have poor seed vigor, so plant these heavier and thin them. A yield of 8 dozen to 8 1/2 dozen ears may be expected per 100 feet of row.

Cultivation should be shallow to avoid damage to the corn roots. Remember: Moisture is essential for good sweet corn production. If less than 1 inch of rain falls during the week, the corn should be irrigated, especially at silking and when temperatures are high and growth is rapid.

Question of the Week: I have sprayed with Malathion as per label direction and still have thrips in my vegetable garden. Why am I not achieving positive results?

Answer: According to LSU AgCenter entomologist, Dr. Dale Pollet, water pH must be adjusted to 5.5 to 6.0 for insecticides to have optimum knock down and control. Most treated water has a pH of 7.0 or higher and will neutralize the effectiveness unless the pH is buffered. If you can catch rainwater and use when spraying insecticides, you will get better results and have to spray less often.

For more information on these and other horticultural topics, call the Lafourche Extension office at 985-446-1316 or come by 402 West 5th Street in Thibodaux. You can also visit our web site at