Garden

Growing Tips: Timing matters in the garden

Recently while having lunch with a friend, I was reminded of the importance of timing when it comes to garden chores. It was August and my friend told me she had just paid someone to prune her trees and shrubs. I cringed. Here in central Pennsylvania, the best time to prune most trees and shrubs is in late winter and early spring. Pruning in late summer and fall can do more harm than good. When completing gardening and landscaping tasks, timing matters, not just for pruning, but for other activities as well. Let's look at three common landscaping chores, the best times to do them and the reasons why timing matters.

Pruning

The best time to see the shape and structure of a tree or shrub is during the dormant season before leaves appear. Crossing or crowded branches as well as dead or damaged wood will be easy to see and prune out. Pruning cuts result in wounds to the live tissue of a tree and can provide an entry point for insects and diseases, so it's best to prune in late winter and early spring, before pests become active and diseases are prevalent. Pruning tends to stimulate new growth, therefore pruning in late summer and fall should be avoided because new growth will not have time to harden off before winter leaving it easily damaged by cold temperatures.

While late winter and early spring are usually the best times to prune, there are exceptions. Spring blooming shrubs that flower on old wood should be pruned immediately after flowering.

The term "old wood" refers to existing branches, not new ones that will appear in the next growing season. Rhododendrons, lilacs and azaleas are examples of spring blooming shrubs that bloom on old wood. Waiting to prune until late winter or early spring risks cutting off branches containing new buds. Shrubs that bloom on new wood can be pruned in late winter or early spring because the blooms will appear on the new shoots. For more on pruning flowering shrubs visit https://extension.psu.edu/pruning-flowering-shrubs and https://extension.colostate.edu/resource/pruning-flowering-shrubs/.

Transplanting

Transplanting can be stressful for plants because it disturbs their roots and interferes with their ability to take up water and nutrients. Plants need time to re-establish their root systems in their new locations. Transplanting is best done in fall and spring because temperatures tend to be more moderate and rainfall more plentiful. Transplanting in summer is not recommended because of the added stress of high temperatures, bright sunlight and frequently dry conditions. Transplanting should not be done while plants are in bloom. Here in central Pennsylvania, fall is a good time to transplant many perennials and to plant deciduous trees and shrubs. Planted in the fall, they will have plenty of time to establish their root systems before the spring growing season and will be better able to withstand summer heat.

Watering

The best time to water a garden is determined by the method used to do the watering. If using a sprinkler or other overhead watering method, the best time to water is early morning. Daytime sunshine will help the leaves dry quickly when watering is completed, making plants less susceptible to fungal diseases which thrive when foliage is wet for extended periods. If watering with a hose, the nozzle should be set to a gentle flow and placed at the base of the plant to avoid getting water on the foliage.

Watering with soaker hoses or drip irrigation systems can usually be done at any time because these methods are designed to slowly add water directly to the soil without wetting the leaves. Sometimes, soaker hoses develop tiny holes which shoot small sprays of water upward. In that case, they should be used for morning watering only because they can wet the foliage.

It takes time for water to percolate down into the soil, so watering on windy days and hot, sunny afternoons is not recommended because too much water can be lost to evaporation before it has a chance to seep in. However, in an emergency, when plants are beginning to wilt, it may be necessary to avoid further damage.

The frequency of watering is another consideration. Infrequent deep watering is preferable to frequent shallow watering. Frequent shallow watering encourages plants to develop shallow root systems because that's where the water is. Deep watering encourages plants to send roots deep into the soil, making them better able to anchor the plant, access nutrients and find moisture during dry spells.

It's easy to assume that the right time to do garden chores is whenever we have time to do them, but that's not always the case. The natural world has its own timetable and knowing what to do when can often mean the difference between disappointment and delight.

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Debra C. Burrows, PhD, is a retired Penn State Extension Educator and a certified Master Gardener. She can be reached at dcb3@psu.edu.