Good nutrition is very essential for your fruit trees to produce fruit and give you an abundant harvest. Much like vegetables, flowers and other plants, they need some extra nutrients too. To know when and how to give your fruit-bearing plants their much-needed boost, keep reading.
When to fertilize?
Keep in mind that there is definitely a right time to fertilize and that is just before the bud break. This is when your trees are beginning their annual growth cycle and this is the time when they need and eat food the most.
Ideally, you can fertilize up to a month before this. But in case you’ve missed this moment and your trees had already begun to bloom, you can still fertilize until June.
It’s strongly suggested NOT to fertilize in late summer or fall because the new growth put on by the trees can be damaged by extreme cold. If it’s a bit late in the season and you still want to feed your trees, you can mulch them with compost and top-dress with soft-rock phosphate. However, all nitrogen fertilizers should be avoided.
A trees’ need for fertilizer varies widely from species to species. Not all trees need annual fertilizers. This can change from year to year and depends on a number of factors. So it is important that you observe and interact with your fruit-bearing trees.
Too much fertilizer can lead to lots of leaves and shoots but not a lot of fruits. Too rapid growth can make your trees weak that may lead to broken branches later in their lives. Too little fertilizer, on the other hand, can cause slow growth and under-performance. Which means you may not be able to get as much fruit as you want during harvest time. If your trees are planted in poor soil, then it’s a must that you give them enough fertilizer because not doing so can lead to nutrient deficiencies, poor health, and low immunity to fight diseases and pests.
The good thing is that fruit trees are pretty good at telling you what they need by simply taking measurements in the winter or early spring while it is dormant and before they grow again for the new season.
How to measure your trees’ growth?
- Locate the last year’s growth rings. This is the point on the branch where the tree started growing in the last season. The growth that you are to measure is often a different color than the rest of the branch.
- Measure from the growth ring all the way up to the end of the branch. Repeat this at several spots around the tree.
- Calculate the average of the measurements. This will be the annual growth of the tree from the previous season.
You will have to take time and repeat doing this series of steps for each of your trees since even trees of the same variety and age may not have grown at the same rate, thus they would have different fertilizer needs.
Use the guide below to evaluate your trees’ annual growth. If a tree’s growth rate is at the low end, or below the annual target growth, then it is a must that you fertilizer this specific tree this year.
For trees that have a positive growth, or at the high end or above the annual target growth rate, there’s no need to fertilize for this year. But it’s important to measure again next year for any changes.
- Non-bearing young trees
- Peaches and nectarine should grow 18”-24”
- Apples and pears should grow 18”-30”
- Plums and sweet cherries should grow 22”-36”
- Tar Cherries should grow 12”-24”
- Mature bearing trees
- Peaches and nectarine should grow 12”-18”
- Non-spur apples and pears should grow 12”-18”
- Spur apples should grow 6”-10”
- Plums and sweet cherries should grow 8”
- Tar Cherries should grow 8”
Choose the right fertilizer.
Fruit trees should be given organic, high nitrogen fertilizers. Good organic nitrogen sources are as follows:
- Blood meal
- Soybean meal
- Composted chicken manure
- Cottonseed meal
- Feather meal
In addition to nitrogen, your trees also need macro and micronutrients. Adding compost every time you fertilize will provide organic matter and trace minerals.
Conducting a soil test can tell you if phosphorus, potassium or other nutrients may be needed in greater amounts.
Calculate the right fertilizer amount.
As discussed earlier, it is important that you don’t give too little or too much fertilizer as this can harm your trees. Below is a guide you can follow to determine the correct amount of fertilizer to use on each tree:
- Trees need 0.10 pounds of “actual nitrogen” per year of age, or per inch of trunk diameter which is measured 1 foot above the ground. Do not exceed 1 pound of actual nitrogen per year. If your tree has a diameter of 5 inches (or, if your tree is 5 years old), multiply 5 by 0.10 pounds of nitrogen, equals 0.5 lb. So your tree needs 0.5 lbs of actual nitrogen.
- Keep in mind though that “Actual nitrogen” is not as simple as just weighing out that amount of fertilizer, because there is more in a fertilizer than just nitrogen.
- Note that the NPK numbers on fertilizer show the percentage of nutrients per pound of fertilizer, not the actual amount. N, P, and K refer to nitrogen, phosphorus, and potassium respectively.2. Let’s take an example. If the N listed on the fertilizer package is 7 (meaning 7% nitrogen), such as with E.B. Stone’s Fruit Tree fertilizer, then there are 0.07 pounds of actual nitrogen for every pound of fertilizer.
In order for you to calculate how much fertilizer to apply, you need to divide the amount of actual nitrogen the tree needs by the amount of actual nitrogen per pound in the fertilizer.
So, using the previous examples, a five-year-old apple tree needs 0.5 lb of nitrogen. The E.B. Stone Fruit Tree Fertilizer has an N-value of 7 on the package, which means it has 0.07 lb nitrogen per pound of fertilizer. Divide 0.5 lbs by 0.07 lbs. The answer will be 7 lbs. Which means 7 pounds is the amount of this specific fertilizer that you need to apply on the tree.
Finally on to Application! I’m an Athlete not a Mathlete after all!
Now that all the dry, boring math is out of the way, we can get to work! Apply the fertilizer evenly starting a foot away from the trunk and continue all the way to the drip line – the perimeter of the tree’s farthest reaching branches. This will help the tree eat the fertilizer most efficiently.
- Spread the fertilizer on the ground and rake it.
- You can also dig a series of small holes that are 12” to 18” apart. And then spread the fertilizer. This may require a bit more work but this ensures that the fertilizer is reaching the tree’s roots.
- Spread an inch-deep layer of compost around the water and water well.
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