By Dirk Coburn, MCH, Horticultural Specialist at Weston Nurseries
It is as important as ever to water newly planted trees, shrubs, perennials, and groundcovers. The ground is dry deep enough that rain has a large volume of soil to remoisten. Winter survival of your plants depends on continued attention to watering them.
The general principles of watering remain the same for all plants in all settings:
- WATER DEEPLY each plant that has been planted this year, using at least enough water to get the soil wet throughout the roots and beyond. That way, the root system will grow larger and deeper to seek the water in adjacent soil. Establishing deep roots makes a plant more drought-resistant. If you get a rainstorm of 1 inch or more, that is sufficient water for about a week. Otherwise, you need to provide additional water.
- WATER OFTEN ENOUGH so that the soil never goes “bone dry”. Soil that lacks moisture or humidity kills hair roots, and hair roots are the ones that gather water for a plant.
- DO NOT WATER TOO OFTEN. Soil that is constantly wet or soggy never allows air to pass through it. Because most plants – especially woody plants – require their roots to exchange oxygen for carbon dioxide, the soil must allow air to pass through on a regular basis. If you refrain from watering too frequently, then there is no practical upper limit to the amount of water that you can use. If you have a very sandy or otherwise fast-draining soil, you can double or triple the minimum recommended amount of water.
- WATER THE ROOTS, not the foliage. Watering the foliage of plants is of no great benefit at best, and can promote fungal foliage issues at worst. If you must use a method that gets foliage wet, do it in the morning when the foliage will usually dry during the day. Foliage that goes wet into a cool night invites spotting, withering, or other issues. While the issues are usually non-mortal, they degrade the look of your landscape.
These principles lead to different guidelines for watering various plants in various environments. For example, Weston Nurseries’ recommended guidelines for watering newly planted trees and shrubs can be found on our website at:
If you are watering deeply enough, trees and shrubs planted in the ground should not be watered more frequently than once a week. Lawns, shallow-rooted perennials, or container plantings may need more frequent watering.