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3 Questions about Thinning Apples

By Nate Krause on May 24, 2021

The beautiful bloom is over and now is the time to start thinning your apple trees. This can seem counter productive but it is one of the most important aspects of growing apples and the most time consuming. Many large orchards use different chemicals to thin out their crops however these chemicals are hard to use and could risk losing your entire crop if you use it wrong. That is why we hand thin over 4,000 trees, yes you heard me 4,000 trees. It is an overwhelming task but is what has worked for us through the years. We spend hours and hours clipping of small apples on each individual tree. When I go home at night and I close my eyes all I see are those little apples.

So why is it so important to thin your tree? I have come up with four reasons:

  1. To discourage over bearing and early fruit drop
  2. To encourage fruit size, color and quality
  3. Help avoid limb damage due to heavy fruit load
  4. Stimulate next years crop and help avoid biannual bearing

What is biannual bearing? Let’s talk about the last one we mentioned biannual bearing. All 4 of these benefits to thinning come back to a very important thing to remember about your apple tree and that is that it takes energy to produce apples. If the apple tree has too much fruit it will have all kinds of problems. All of its energy will be used and will have no energy for next year. That is what they call biannual bearing. You may have a tree at your house or family member, neighbor or whomever and notice that one year they have all kinds of fruit and the next year have nothing. That is called biannual, the tree used up all of its energy and had nothing left for the next year.

Now let’s get really nerdy about apple trees. Some varieties are more likely to be biannual then others. Jonagold for instance will more then likely always produce fruit with minimal thinning. Honeycrisp on the other hand are very susceptible to biannual production. You may ask what makes a tree biannual? The short answer is this; At 10-12 mm fruit size once it starts to develop seeds the applet actually releases a hormone that builds up on the next year’s spur. This hormone tells the tree if it needs an apple or whether it should rest next year. This gives you a relatively short amount of time to thin with Honeycrisp.

So how much should I take out? This is a great question without a very good answer. It all depends on the size of your tree and the health. Obviously the larger the tree the more fruit can be left on the branches. If your tree does not look very healthy, I would suggest taking out more apples to let it push energy into getting healthy rather then making fruit. On a large tree I would start with just leaving the largest applet per cluster, expect Honeycrisp. Then look at the tree and think about crop load, once those apples get bigger can that tree handle it. Normally if a tree is growing vigorously we put on 20-25 apples per tree its 1st year of production. From there we double it as long as the tree is doing well each year. But like I said it all depends on your tree size and health.

It is very important to thin your trees to improve the health of your tree and quality of your fruit. Hope this blog helps you in your quest to grow the perfect apple tree.