Planting Container-grown Plants

Container-grown plants have become the most popular method of growing plants for sale by the nursery industry. In theory, container-grown plants can be transplanted year round, however, extra attention to watering must be made when transplanting in late spring or summer. Late fall and early spring are considered ideal planting times because roots will have more time to grow into the surrounding soil before the stress due to new foliage growth and high temperatures occurs.
Ideally, the hole should not be dug any deeper than the root ball. If you dig too deep, firm the bottom of the hole to reduce settling. In most compacted urban soils, root growth from the bottom of the root ball will be limited by inadequate aeration and possibly excessive moisture.

Widening the planting hole is an ideal way to enhance plant growth. A planting hole that is three times the width of the root ball is ideal. When digging in heavy soil the sides can become slick especially if the soil is somewhat wet. Slick sides can act as a physical barrier to root growth and moisture movement. Use a shovel to make the sides of the hole rough and irregular.

Always water plants thoroughly before transplanting. Remove the plant from the container by turning the plant upside down and giving the top edge of the container a sharp rap. Catch the root ball in your hands as it slips from the container. If plants have become overgrown in the container and the root mass is growing in a tight, compact circle the roots should be loosened before planting. If the roots are only slightly encircled you can loosen and spread them out by hand. Many gardeners cut the outer roots with a sharp knife by making vertical cuts approximately 2 inches into the root ball on two to four sides of the root ball. After the roots have been loosened or cut, carefully place the plant in the hole. Always pick the plant up by the root ball never by the trunk or stem (can cause damage to fine root hairs).

Soil that was removed from the hole should be used to refill the hole. Research has shown that adding organic matter to individual holes does not improve plant growth and in some cases can be detrimental. The primary reason for digging a wide hole is to improve soil aeration and to reduce compaction. If an entire bed is prepared for plant, it is recommended that a 2- to 3-inch layer of organic matter be incorporated into the soil.

Lime and superphosate should be mixed with the backfill, if needed, based on a soil test. Fertilizer should not be added at planting since it can burn the roots.

Fill in around the plant with soil until the hole is one-third full. Lightly firm the soil around the root ball. Loosen and break up any clods of soil before backfilling. Clods can create air pockets around the root ball. Before finishing the filling process, make certain the plant is straight and at the proper planting depth. It is important when planting (particularly container-grown material) to avoid covering the top of the root ball with more than 1/2 to 1 inch of fine soil. Ideally it should be level with the soil surface.

Apply a 3-inch layer of mulch over the planting hole and water. Mulch will help maintain soil moisture and reduce fluctuations in soil temperature. The mulched area should be expanded as the plant grows.

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