Planting in early spring is best for woody deciduous shrubs and trees, while the ground is workable not frozen.  Plants will do better if they are planted while dormant or close to it. For early flowering plants like rhododendrons or lilacs, my goal would be to plant before the flowers buds start to break.

It also helps to plant when the weather is cooler. By May, there is the potential for warm or even hot weather.  If you wait and the plant is already flowering and the weather warm, you are causing more stress on the plant than if it is dormant and the weather is cool. By doing it earlier, the plant “wakes up” and it is already in its new spot and ready to go.

Having said that, you won’t necessarily be doing any permanent damage to a plant if it gets planted in May or even early June. Sometimes circumstances don’t allow for earlier planting. But regardless of when you plant, it is important that you keep the plants well watered for the first year (or ideally two years). This means the entire first season, well into fall, you should water it well if it doesn’t rain.

The watering  benchmark of an inch a week is often used but this measure can be difficult to gage. If there is a steady rain for a day or so, you are probably good for that week. If not, then water your plants that week. A thunderstorm, even if heavy, generally does not do a good job of watering because the rain comes down quickly and runs off quickly.

Find more information on watering new trees and shrubs from this helpful guide. 

Courtesy of the NYBG Plant Information Service

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