After installing new trees and shrubs in your yard, it is important for the first year or two after installation to keep your new plants from drying out. It is also important not to over-water them. The amount of watering that is needed will depend not only on the size of the plant, but on local rainfall, drying winds, the season, soil type, the planting site, and the overall health of the plant. Mulch your new plants to reduce the frequency of watering during dry spells. Mulches help keep soils cool and reduce water loss through evaporation.
As a general rule, let your finger be the judge. Move some mulch aside and feel the soil around the plant. If the soil is wet or muddy, it is too soon to water. If it is hard and dry, you have waited too long. A good deep watering once a week is better than spraying the plant with a hose every day. Deep watering encourages the roots of the plant to grow deeply into the soil, making the plant better able to survive droughts and obtain more nutrients. Watering every day encourages surface rooting which will not enable the plant to survive normal environmental stresses.
A three-inch layer of mulch will settle to two inches, which is appropriate to keep weeds down, hold moisture in the soil and maintain a neat, fresh appearance. A light layer of mulch may be added yearly to freshen the beds and replace mulch that has deteriorated.
No matter what you see in parking lots and other peoples’ yards, never pile mulch against the trunk of a plant. Keep the mulch a few inches away from the bark and do not apply too much mulch. When mulch comes in contact with the plant, several problems are encouraged. The plant will grow more surface roots, which as stated previously, will not allow the plant to survive normal environmental stresses. The bark can begin to rot away which encourages fungal and disease infections. In winter months, voles and mice can tunnel through the mulch to the tree and chew all the bark from around the plant. This is called girdling and will kill the tree if the area chewed encircles the entire plant.
For deep watering make sure to thoroughly soak the entire area around the plant. Leave the garden hose on a trickle at larger trees and shrubs for 15-30 minutes depending on the size of the plant. Sprinklers do mostly light watering or waste water over too large of an area and should be avoided.
When watering individual plants with a hose, attach a water breaker to the end. It softens the flow of water to a small area but does not wash away the soil. Avoid using a trigger-type nozzle as it washes soil away from the roots of the plant.
Try to avoid watering your plants in the heat of the day and try not to get water on the foliage, especially red or purple colored leaves. The water is needed around the roots of the plants, not on the leaves. The drops of water that remain on the foliage can act like tiny magnifying glasses and “burn” the leaf from the sun. Water splashing on the foliage also encourages some fungal diseases by spreading the disease from leaf to leaf.
Besides examining the soil, check your plants periodically for signs of stress to help you determine when to water. Some signs that your plants’ survival may be threatened are:
Leaves turning from shiny to dull or the color may change from bright to dull green.
New leaves and leaves that are normally stiff begin to wilt. Stiff leaves such as holly leaves, pine needles and juniper branchlets do not wilt as they dry out, but new growth on the branch tips of these types does.
Flowers fade quickly and fall prematurely.
Older leaves turn brown, dry, and fall off.
Curiously, similar symptoms appear on plants that are being over-watered. Excessive water can cause root rot and the plant will wilt because it is lacking oxygen and consequently is unable to take up moisture. Always feel the soil before watering.
Watering plants correctly is vital for developing and maintaining your landscape plantings. It is important to water thoroughly yet allow the soil to become fairly dry between waterings. Know the type and condition of your soil-plants in clay soil will need less watering than plants in sandy soil. Learn the cultural requirements of the plants that you install. Use mulch properly to help reduce water loss. Once trees and shrubs are established they can continue to mature with very little assistance from us and thrive for years, decades and sometimes centuries.