Without a doubt, water is the key to re-establishing the root system of transplants. If the roots lost in transplanting are not quickly replaced, the plant will lose vigor. During extremely hot, dry weather, it may actually decline and die. So, proper watering is very important in post planting care of landscape plants.

A. Frequency of Application - A common question by rookie gardeners is, "How often should I water my transplanted tree? Once a week? More often?" Unfortunately, the answer is not that simple. An often used generalization is that landscape plants need about one inch of water per week in the form of either rain or irrigation during the growing season.

However, the amount of water any particular transplant in your particular garden will need depends on several factors including:

1. Air Temperature - The air temperature in the area following transplanting will, of course, govern the amount of evaporation that takes place. The hotter and the dryer the weather, the greater the amount of water that will move through the plant and be lost through the leaves. If the temperatures are cool and you receive regular rainfall, of course the amount of water you need to provide will decrease.
    

2. Soil Type - Heavy clay soils will drain slowly and may easily become saturated with way too much water. These types of soils may require that you irrigate more frequently but with smaller amounts of water at each application to reach your goal. Avoid allowing water to puddle up and stand in the planting zone since this may lead to root rot problems.

   Sandy soils drain too rapidly. So, with these soils, you may need to apply water more frequently or at higher volumes to avoid a dry, droughty condition.
    

3. Type of Plant - As mentioned, most landscape plants need the equivalent of about one inch of water per week during the growing season. However, this can vary greatly depending on the species of plants. Those from arid regions of the world or so-called succulents such as cactus or sedums will suffer quickly from too much water. Species originating from wetlands may need more water than others. Know your plants.
    

4. Mulch - As discussed later in this section, a good layer of mulch will help to conserve moisture and reduce the need for irrigation. It does this by shading the soil to minimize evaporation and organic mulches will absorb water and make it available to the plant roots later.

B. Method of Irrigation - There are several ways to deliver the water needed by the transplants. Some methods will be more convenient for you because they deliver water "as needed" which will help minimize the chance of over or under-watering.

1. Hand Watering - With a single new tree or just a few perennials, you might just water using a bucket, sprinkler can or garden hose. The key here as with all methods is to keep the root system moist but not waterlogged. Also, it is very important to put the water close to the base of the plant especially for trees. Studies have shown that, if you place the water outside of the original root ball area, it may not penetrate back into the root zone. The plant may appear to die from lack of water even though you know that you have been irrigating it regularly.
    

2. Drip or Trickle Irrigation - These are automated systems that consist of a series of hoses with individual spouts called emitters that are placed at the base of each plant or group of plants. Or, these can be made up of so-called "weeping" hoses that "sweat" the water out onto the soil. In either case, the plants are given a slow, steady supply of water automatically while the system is turned on.

   These are systems that are generally used for lawns. Although they may be used for beds and borders too, they will need to be adjusted in order to avoid overwatering. Generally, trees, shrubs, perennials and other plants in the beds and borders do not need as much water as the lawn. Also, many of these systems are set up on a timer basis which works fine for the lawn which can absorbs some extra water easier than trees, shrubs and perennials.
    

3. Watering Bags - In recent years, plastic type bags have been introduced which may be wrapped around the base of a tree or shrub. They are then filled with water which slowly releases itself into the root zone of the plant. These containers need to be filled periodically but, if kept supplied with water, they will automatically irrigate your plant.