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Watering Guidelines

The guidelines below are just that: guidelines.  It is impossible to dictate a watering schedule that will be right for every plant all the time.  When deciding how much or how often to water, be sure to allow for weather conditions such as rainfall and the drying effects of high temperatures and wind.  Also consider location and plant size.  Placement near a building may reflect heat or affect the amount of precipitation received, either of which may mean you need to water more.  And generally, the larger the plant, the more water it will need.

The objective with any watering is to get moisture to the roots.  Therefore, the best time to water is early morning.  Watering later in the day after the sun gets hot increases evaporation (and your water bill), and you risk not delivering enough water to the root system below.  Likewise, watering too late in the day may leave exposed areas of a plant too wet overnight, stressing the plant and leaving it more susceptible to foliar fungal diseases.

With these precautions in mind, the guidelines below will help you provide the right amount of water to your new garden. 

Sod   Perennials/Shrubs/Trees   Evergreens   Containers/Annuals

Sod

Water your new lawn immediately after installation (within half an hour).  Water once or twice daily for the first two weeks until the grass has rooted.  Sod should be watered so that the sod strip is wet the entire thickness of the strip, and the soil underneath is moist to a depth of about one inch.  Do not overwater.  Saturating the soil below the sod removes oxygen needed for proper root growth.

After the first two weeks, begin watering less frequently and more deeply until the sod is firmly established.

Be sure to avoid heavy traffic or mowing of new sod for the first three weeks.

Perennials, Shrubs and Trees

Proper watering of perennials, shrubs and trees is critical during the first year after planting.  The basic rule of thumb is to water deeply, but infrequently.  The best way to do this, especially for larger plants such as trees and shrubs, is to place an open-ended hose at the base of each plant and let water trickle very slowly into the soil—about 45-60 minutes for smaller plants and 60-80 minutes for larger plants. You want to get water to the root ball and surrounding soil of each plant, or at least 18” down with each watering, in order to encourage a deep, drought-tolerant root system. 

Then let the soil dry out for a few days before watering again.  Watering too much or too frequently can literally drown plants because their root systems need oxygen to survive.

Do not rely solely on a plant’s appearance or the soil surface to determine if you need to water.  Stick a coat hanger or sharp wooden stick 4 to 6” into the root ball, just as you would test whether brownies are done baking by sticking a toothpick into their center.  If the coat hanger or stick emerges from the soil dry, it’s time to water.  Another trick is to scoop up a handful of soil from that depth and squeeze it into a ball.  If the ball holds its shape after you let go, the soil is still wet.  If the ball falls apart, it’s time to water.  Finally, remember that, generally speaking, the larger the plant, the deeper the water needs to go.

With proper care, after the first year most plants have established themselves enough that they can survive up to three weeks without water.  Although frequent watering is not necessary at this point, check regularly to make sure plants are not drying out too much, especially during periods of excessive heat or drought.  Keeping your garden well hydrated will help it remain healthy.

Evergreens

Pay special attention to watering evergreens as they are particularly susceptible to over-watering.  A pine suffering from lack of water looks the same as one whose roots are drowning—drooping, falling or browning needles.  The only way to know for sure whether watering is needed is to test the soil well below the surface.  As with deciduous plants, stick a coat hanger or sharp wooden stick 4 to 6” into the root ball.  If the coat hanger or stick emerges from the soil dry, it’s time to water. You can also try scooping up a handful of soil from that same depth and squeezing it into a ball.  If the ball holds its shape after you let go, the soil is still wet.  If the ball falls apart, it’s time to water.

All plants should be watered during autumn, although at a reduced rate, until after the leaves have fallen and before the ground freezes.  Evergreens, however, should also be watered thoroughly once or twice during warm spells in winter, especially during the first year.  Although their growth rate slows down in the winter, evergreens do not go dormant in quite the same way as do deciduous trees.  Because they keep their foliage during the winter months, evergreens lose moisture to drying winds and low precipitation throughout the year.

Containers and Annuals

Containers need to be watered daily unless it rains.  The drainage holes in pots reduce the risk of over watering, but the high rate of evaporation in containers means that even a few days with no water in hot, dry weather may kill the plants inside.

Annuals that are planted in the ground are not as susceptible to evaporation, but are still vulnerable in that they have shallow root systems.  Do not wait to water until annuals begin to visibly wilt.  Instead, water as soon as the upper 2 to 3” of soil dries out.