We are almost finished. Don't blow it now after doing all that work. Aftercare is important.
Watering and Mulching
Most newly planted shrubs need an inch of water, or the equivalent of a 5 gallon pail, a week during the first growing season to help their root systems develop. Consequently, when rainfall is insufficient they will need supplemental water from you. Water with a slowly dripping garden hose or use a soaker hose system which delivers water efficiently and gradually. Continue watering regularly until mid-fall and then taper off.
The 3 or 4 inch layer of organic mulch that you spread over the root zone at planting time will gradually decompose in summer heat, Add more periodically to maintain it at about 3 inches. The mulch will absorb and retain moisture, reduce run-off in heavy rains, and block evaporation of moisture from the soil. In winter it will buffer soil temperature fluctuations.
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Do not fertilize newly planted shrubs during their first year in place. Planting the shrub properly and keeping it watered is more important to encourage good root growth. Most of the top growth a shrub puts out in its first year is stimulated by the starches already stored in the shrub. Extra fertilizing after planting only encourages leafy growth at a time when root development is more important.
Begin fertilizing in the early spring or late fall a year after the planting time. Sprinkle a balanced, all-purpose slow-acting granular fertilizer, (or one formulated for acid loving shrubs such as hollies and rhododendrons) over the shrub’s root zone. The rain or watering will soak it in through the mulch and soil. Keep this area free of grass so that it does not use the nutrients intended for the shrub. After 3 or 4 years, shrubs that are regularly mulched so that organic matter is introduced into the soil to keep it fertile, no longer need annual fertilization.
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There is rarely any need to prune a newly planted shrub unless a branch is injured or broken during the process. If any branches cross and rub one another, bruising their tender bark, remove one of them. Most nursery-produced shrubs are usually appropriately pruned. After a year or two some corrective pruning for shape may be necessary. Always use sharp hand pruners or loppers.
If you have planted shrubs to make a hedge, give them a year or two before shearing them. Forsythia and privet may grow tall and leggy. Prune them back half way to encourage the development of lower branches. Do not prune lower branches of shrubs intended for hedges shorter than the top branches. They may not get enough sun.