When is the best time to plant shrubs?
In South Carolina, fall is the best time to plant shrubs for successful establishment and optimal root growth. Although the above portion of the shrub is dormant in fall and winter, the roots continue to grow since the soil is not frozen.
This allows the shrubs that were planted in the fall to use carbohydrates produces during the previous growing season for root growth. By the next growing season, the roots growth that occurred during fall and winter can better access the necessary water and nutrients for optimum plant growth.
When establishing shrubs, adequate and appropriate moisture is essential. Spring and summer planted shrubs require more careful monitoring of soil moisture due to the dry and hot season and are at a higher risk of drought. Newly planted shrubs have fewer roots available to meet the water needs of actively growing shoots during the spring and summer.
Remember to always get a soil test before starting any planting project to test for soil pH and nutrient availability. Ideally, you would want to test the soil three to four months before planting in case you need to raise the pH with lime or lower with sulfur.
Research suggests backfilling (the soil used to fill in around the root ball) the planting hole with only native soil rather than adding organic matter. Amending the backfill causes the soil structure of the planting hole to be dramatically different from the native soil. This dramatic difference encourages the plant roots to stay within the planting hole instead of moving out into the native soil. When preparing a planting bed for more than one shrub, use organic soil amendments throughout the entire area to create a uniform environment for the roots.
Select the right plant for the right space. If the area has poor drainage, elevate the bed 8 to 12 inches using native soil or topsoil made up of mostly native soil and a small portion of composted organic matter. Plant shrubs high to allow water to drain away from their roots. Plant the shrub so the root flare (where the trunk gradually widens as it approaches the soil line) and topmost roots are level with the ground or slightly above the soil level. In poorly drained or compacted soil, place the top of the root ball about 2 to 4 inches higher than the surrounding soil.
Containerized shrubs may have extra soil on top of the root ball. Locate the root flare and uppermost roots before planting.
Measure the height of the root ball from its bottom to the root flare to determine how deep to dig the planting hole. Never dig the planting hole deeper than the height from the uppermost roots to the bottom of the root ball.
Make the planting hole two to five times wider than the root ball. Roots will grow more quickly into loosened soil and will improve the establishment time of shrubs.
Apply two to three inches of organic, natural mulch over the planting area to prevent weeds, retain soil moisture, moderate soil temperatures, and eventually improve soil organic matter content.
Keep mulch two to three inches away from the trunk or stems. Mulch piled against the trunk increases the chances of stem rot. Organic mulches include pine needles, pine bark, hardwood bark, wood chips, and partially ground leaves.
Proper water application after planting is essential to the plant’s survival. Water slowly and well after mulching. In the first year, apply water directly to the root ball because the roots have not spread far into the surrounding soil.
Proper watering practices result in plants that establish more quickly and help the plant to become drought, pest, and disease resistant.
For more information on planting shrubs, please visit the Home and Garden Information Center website at hgic.clemson.edu. Tune in on Tuesday nights to watch “Making it Grow” at 7 p.m. on SCETV or mig.org. E-mail Outen at callenb@clemson.edu.
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