Watering and Mulching

Annuals and groundcovers should be watered while still in their produc­tion containers and just prior to transplanting. After installation is com­plete, the entire planting bed should be thoroughly watered. The new planting should be carefully monitored in the days that follow to ensure that the plants get adequate moisture to prevent wilting and encourage deep root growth. Watering should occur early enough in the day to per­mit complete drying of the foliage before temperatures cool, possibly providing an opportune environment for disease development.

Trees and shrubs may receive some water as the backfill is added. For large soil balls, that is especially important. Regardless of the size, all trees and shrubs will need water as soon as possible after the trans­planting is completed. The water will promote settling of the backfill which may necessitate either additional backfill or the slight lifting of the plant to return it to the proper planting depth. The latter is common with bare root forms of plants. Otherwise the plant may sink and not establish successfully.

Before applying the water, a bermed ring of soil should be built around the plant, using excess backfill. It should be compacted enough to retain water and it should be several inches in height. The berm should be built directly over the soil ball and closely approximate the diameter of the soil ball. It should not overshoot the soil ball since the intent is to ensure that water applied within the berm permeates the soil ball rather than flowing around it into the looser backfill. It may be necessary to fill the basin several times in order to ensure a suitable level of soil moisture for the new transplant.

After watering, mulching is recommended for trees and shrubs in all but poorly drained locations. Mulching is the application of loose aggre­gate materials to the surface of the planting bed or backfilled planting pit. The materials may be organic or inorganic. Examples of both types and their advantages and disadvantages are listed in Table 10-1. To be effective in moisture retention and weed control, the mulch must be applied three to four inches deep. A shallow layer of mulch has only cosmetic value. It does not reduce sunlight enough to discourage weed

TABLE 10-1. Characteristics of Common Mulches

Organic Mulches

(peat moss, wood chips, shredded bark, chipped corncobs, pine needles)

Inorganic Mulches

(marble chips, crushed stone, brick chips, shredded tires)

reduce soil moisture loss

reduce soil moisture loss

often contribute slightly to soil nutrition

do not improve soil nutrition

may alter soil pH

seldom alter soil pH

are not a mowing hazard if kicked into the lawn

are a hazard if thrown by a mower blade

may be flammable when too dry

are nonflammable or fire-resistant

may temporarily reduce nitrogen content of soil

have no effect on nitrogen content of soil

require replacement due to biodegradation

do not biodegrade

may support weed growth as they decompose

may retain excessive amounts of solar heat

Nylon or plastic guying ties

figure 10-8. Key points in tree and shrub installation (Delmar/Cengage Learning) seed germination and growth, nor does it retain moisture or insulate the soil surface against temperature fluctuations.

Mulch should fill the ringed berm around the new transplant, but not be in contact with the trunk or crown. It is especially important that the mulch not bury the root flare. Too much moisture at the base of the plant can promote disease development or insect injury. Figure 10-8 illustrates the key points in tree and shrub installation.