I love gardening for many reasons. I like fresh air, body activity, mental stimulation, constant change and much more. The autumn season is a good time to reappear, to go outside and do important maintenance in the garden and in the countryside. Big dividends in future seasons are the additional reward.
One of my favorite parts of gardening is that I’m always learning. Fortunately, I recently learned something that changed my approach when fertilizing established trees and shrubs.
For most of my garden life, trees and shrubs that needed nutrient intake were spread out every year in early spring, just before the start of active growth for the year. This timing has been the generally accepted practice of gardeners and experts around the world for years. And although the beginning of spring is a good time, new research suggests that there is an even better time.
Contrary to traditional wisdom, many experts now consider after autumn, about a month after the first deadly frost, to be the perfect time to apply fertilizers. We now know that plants use nutrients in different ways throughout the year.
In the past, the most common reason for fertilizing in the fall was the fear that plants and trees could resume their growth when unusually hot weather returns, only to be burned or damaged by upcoming colder temperatures.
The key is to understand the difference between the beginning of autumn and the end of autumn. If you fertilize in after summer or early autumn, when the temperatures are still warm and the plants are still actively growing, it is likely that new shoots will appear and damage to the new tender foliage may be the result.
The justification for after autumn fertilization makes sense if you understand why. At this time, deciduous trees and shrubs lost their foliage for the year and the active growth of plants and trees slowed down. Instead of growing new leaves, the roots of trees or shrubs set up absorb nutrients from the soil and apply them to important functions of promoting health, such as resistance to ailment and the development of roots. Excess nutrients are stored in the roots and become immediately available when they are needed for new growth in the spring.
However, keep in mind that not all established plants and trees are candidates for a regular fertilizing program. I always suggest that a soil test be obtained through your local district extension office. Just collect a representative soil sample around the area where your trees and shrubs grow. Inform the extension service that you want to have the soil tested for this.
The report will tell you what nutrients may be lacking in your soil for optimal growth. The report will also suggest the correct type and amount of nutrients to be added.
A common mistake, not only with trees and shrubs, is the assumption that fertilizer can and should always be added, and if a little is good, the better. Nothing could be further from the truth. Excess nutrients are wasted and can also contaminate the soil and the environment.
Plants and trees are much more demanding than we give them credit for. In simple words, they have integrated clocks, timers, calendars and monitoring systems that do not require our intervention as much as we think, just like with autumn fertilizing.