While most healthy trees and shrubs do not need fertilizer, sometimes a weaker tree needs some extra nutrients. Likewise, fruit trees may need fertilizing for better growth and harvest. Here we’ll walk you through how to fertilize trees, namely:
- what is a fertilizer
- when to fertilize trees
- how to fertilize trees
What is in Tree-Fertilizer?
Firstly, let’s look at what is in fertilizer. Standard fertilizers contain nitrogen (N), phosphorus (P), and potassium (K). Trees growing in soils that lack these chemicals may grow poorly. However, most New York State soils contain enough phosphorus and potassium. Likewise, while nitrogen is variable, healthy trees do not require a boost of nitrogen. Indeed, too much nitrogen can back-fire by encouraging the health of some pests.
What Do These Ingredients Do?
Now that you know what is in fertilizer, let’s learn how these compounds help your trees. Firstly, nitrogen aides leaf growth. However, the nitrates supplying the nitrogen can dissolve in water. So, choose slow-release or water-insoluble (W.I.N.) fertilizers. These will provide a steady source of nutrients. Next, phosphorus can help root growth, flowering, and fruiting. Finally, potassium can help with overall health, root growth, and disease resistance. For both potassium and phosphorus, only apply if a soil test shows a lack of these nutrients.
What Trees NOT to Fertilize
Though some trees may need fertilizing, there is no need to fertilize healthy trees. In fact, over-fertilization can harm or even kill your trees. So before rushing off to fertilize your trees, make sure they need it. For instance, do not fertilize newly planted trees! If absolutely necessary, wait until the second year after establishment. Similarly, only fertilize young trees if they really need it, and use a slow-release fertilizer. Lastly, mature trees should not need fertilizer.
How to Know if a Tree Needs Fertilizer
So we know that we need to be careful when fertilizing trees. On the one hand, most soil has plenty of nutrients. On the other hand, too much fertilizer can harm or even kill healthy trees. So how can you tell if a tree needs fertilizer? Here are a few things to look for:
- pale or undersized leaves
- dead branch tips/ dieback
- reduced growth rate
This third point is key to knowing if you need to fertilize fruit trees.
How to Know If a Fruit Tree Needs Fertilizer
The best way to know if your fruit tree needs fertilizer is by finding the growth rate. Firstly, find last year’s growth rings. This is the point on the branch where the tree started growing last season. Usually, the newest growth will be a different color. Next, measure from the growth ring to the tip. Do this in several spots around the tree. Now, find the average measurement. Lastly, compare your tree’s annual growth rate. If your tree is at or above the target growth rate, do not fertilize. In contrast, if the growth rate is low, then you should fertilize your fruit tree.
When to Fertilize Trees
In New York State there are two times when to fertilize trees. Firstly, during dormancy. As with winter tree pruning, this ensures that new growth isn’t stimulated during the autumn and winter, which can harm the tree. Secondly, in early spring. In Western NY this means April, or just as leaves are beginning to open. Avoid fertilizing during the heat of the summer. This can burn roots. Likewise, do not fertilize in from late-spring through to autumn. This can stimulate growth that won’t be ready for winter.
When to Fertilize Fruit Trees
Guidelines for when to fertilize fruit trees are similar. In particular, just before bud break. This is when fruit trees are beginning their annual growth. Therefore, this is the perfect time to provide extra nutrients if your tree’s growth rate is low.
How to Fertilize Trees
Once you’ve figured out which of your trees needs fertilizer and when to fertilize those trees, you need to know how to do so. Start by checking the manufacturer’s instructions. Also bear in mind these basic guidelines:
- choose slow-release fertilizers
- spread fertilizer evenly around the tree
- fertilize an area 1.5 times the diameter of the branch spread
In this way, you’ll provide an even source of nutrients to the tree’s roots.
Tree Service in Webster NY
Have more questions about tree care, or looking for arborists in Webster? Let Arbor Tree Experts know. Established in Webster in 1985 we are a fully licensed and insured tree service in Webster. We offer tree removal, tree pruning as well as stump grinding. Likewise, we can help you choose the best trees for your unique landscape. Contact us for a quote.