April and May are classic times to install plants of all types – trees, shrubs, veggies, herbs, groundcovers and flowers.  One of the most basic requirements for ensuring their benefits and longevity is watering…but it’s not as simple as it may seem.  There are many factors that contribute to success.

Find out how much is preferred by the plant.  The best source of this information is the plant care tag that was attached to the plant or pot when purchased.  If this information was lacking, there are many other sources such as the Missouri Botanical Garden, the Morton Arboretum and various land grant university extension web sites.

Water to the bottom of the roots.  Keep in mind the size of the root ball at the time of planting; water until the soil is moistened that deep at first, then keep in mind that roots will grow downward and horizontally.  Shallow watering results in dieback of the roots due to dehydration, while deeper than necessary watering wastes water as there are no roots there to absorb it.  The tricky issue with soil moisture is that it’s nearly impossible to determine by looking at the soil surface.

Instead, use a screwdriver, piece of ree-bar, broken golf club or other metal probe to determine the moisture content in the soil at various depths.  Push it in to the full depth of the device, noting how much pressure it takes to push it downward.  If it slides downward into the root zone easily, that’s a good indication that the soil is moist; if it takes a lot of effort, the soil is probably dry.  If the device is long enough, it’s likely that the soil will be moist up to a certain depth, then dry further down; that’s a good measurement of how deeply the moisture has infiltrated.  A second indicator is to simply feel the soil that sticks to the probe after it is pulled out.  If it is dry and powdery, a thorough watering is probably in order.  If it is muddy, then no water is needed for a few days.  For most plants, unless indicated otherwise, the goal is for new plants to be moist, not soggy or dry.

Apply water slowly.  Slow, gradual watering ensures that the roots are wetted without an excessive loss of applied moisture, which is most pronounced on slopes, where water usually moves away from new plants before it can percolate downward.  Several devices can facilitate slow infiltration such as soaker hoses, buckets with holes drilled in the bottom, 6-7 way hose/bubbler attachments and drip irrigation emitters.

Water as close to the soil as is possible.  In addition to the benefit of slow infiltration the devices listed in the preceding paragraph provide, they also are efficient in that they don’t expose the applied water to the wind above the plants, which can carry it away from the newly installed plants.  If applied at the soil surface or just a few inches above, 90-95% will moisten the roots instead of drift away to another location.

Water in the morning hours.  Morning watering is helpful when soaker hoses and drip irrigation devices can’t be used for various reasons.  If it’s most practical to water with an overhead system, it’s best to water when wind speeds are low, which tends to be in the early morning hours. As well, the sunlight intensity is relatively low in the morning compared to the afternoon, thereby reducing the effects of evaporation and loss to the atmosphere.  Watering in the morning is especially important for large tracts of closely spaced plants such as new lawns and large gardens.

Check soil moisture as plants grow.  As plants get bigger and the seasonal temperatures warm up (or cool down in fall), soil moisture should be checked at least every few days.  As roots expand, they occupy a greater space, thus require a larger area to be watered and monitored for soil moisture.

Apply organic mulch to hold in soil moisture.  In order to conserve applied water, applying a 2-inch layer of wood chips, pine straw or grass clippings will prevent excessive soil moisture loss.