Have you heard the old wise tale that you should wait until after a frost to harvest your apples? I am here to bust that myth. If we followed that rule, many of our apples would be rotten or on the ground by the time we picked them. This is because each apple has a different ripening time, anywhere from mid-August to October.
Instead of waiting until a frost, use a few simple, smart guidelines to decide when to harvest your apples.
Most apple varieties available to home gardeners in Minnesota are harvested after mid-September and before Halloween. This includes Minnesota’s state apple, the beloved Honeycrisp, which we harvest from late September to early October.
Typical ripening by variety
Early season varieties (mid-August to early September)
Beacon, Paula Red, Zestar!, State Fair, and Centennial crabapple (plus First Kiss and SweeTango - not available to home gardeners)
Mid-season varieties (mid or late September)
Chestnut crabapple, Red Baron, Sweet Sixteen, Triumph (new), and Honeycrisp
Late season varieties (late September to October)
Honeygold, Haralson, Frostbite, Regent, SnowSweet, Fireside/Connell Red, Keepsake, and Prairie Spy
Apple ripening varies greatly by variety and even within the canopy of a single tree. Apples in the center of the tree are more shaded and ripen more slowly than apples on the outside and top.
Apple growers can use fruit color, sugar content, loss of starchiness, and flavor to decide when to harvest.
A ripe apple should be sweet, have a pleasant (non-starchy) mouthfeel, and be red with a yellow background color.
Starch to sugar
Throughout the summer, unripe apples contain a lot of starch. As apples ripen, their starch converts to sugar. If you bite into an unripe apple, the starch will create a feeling on your tongue that some may describe as dry, sticky, or astringent. Unripe apples may also be quite tart. If you taste an apple like this, it is not a fault of the variety — the apple is meant to be left alone to ripen longer.
In addition to flavor, look for apples with red and yellow skin. The red is the “over color” and the yellow is called the “background color.” If the background color is green instead of yellow, it is not ripe. A yellow background color is one indicator that the fruit may be ripe or nearly ripe. Please note that many apples will turn color before converting all of their starch to sugar, so the flavor is still a more important indicator than color.
Apples often change texture as they ripen, going from hard to either crisp or mealy. If an apple is hard to bite into, it is probably not ripe yet.
Most UMN varieties, like Honeycrisp, maintain that firm, crisp texture through harvest and storage. Other varieties like State Fair and Zestar! lose crispness during storage.
How commercial orchards measure ripeness
Your local U-pick orchard measures ripeness the same ways described above. But they also have two other tools to more precisely measure ripeness. These include the “starch iodine test,” measuring juice brix (sugar content). Not all orchards use these tests, as some still rely on taste and appearance.
Orchards can closely monitor their apples’ transition from starch to sugar by using a starch-iodine test. They cut open an apple and spray the surface with an iodine solution. The starch in the solution stains the flesh blue — the bluer the flesh turns, the more starch the apple contains. As the apple ripens and converts starch to sugar, the spray will create less blue color. Once about 20% or less of the surface stains blue, orchards harvest the fruit. Home gardeners could use this method, except that finding the correct iodine solution would be challenging and expensive.
We use a refractometer to measure the sugar content (brix) of the juice after blending and straining it from the apple. Ripe apples have a brix of at least 12-13.
Harvesting pre-ripe apples
There may be scenarios where you have to harvest your apples before they are ripe. For example, ripening fruit are attractive to creatures like raccoons, birds, and brown marmorated stink bugs. If you see your fruit getting eaten and cannot protect it, you may have to harvest early to save what is left.
If you do have to harvest under-ripe fruit, your options are:
- Store your fruit for a few weeks before using it.
- Many apples sold to grocery stores are stored for weeks or months before hitting the shelves. To make sure the apples can survive long-term storage, the orchards harvest them 1-2 weeks before peak ripeness.
- Apples are a “climacteric” fruit, meaning that they continue to ripen somewhat after picking. If you have to pick early, try storing the fruit for a while to see if they become sweeter before use.
- Use the fruit in baked goods, sauce, or canned goods. These processes almost always call for added sugar that counterbalances the tartness of under-ripe fruit.
Hillin, Daniel. Grape Berry Ripening and Sampling Techniques. July 2019. Texas A&M AgriLife Extension Service. https://aggie-horticulture.tamu.edu/vitwine/2019/07/15/grape-berry-ripening-and-sampling-techniques/
Fruit Harvest - Determining Apple Fruit Maturity. Oct. 25, 2017. PennState Extension. https://extension.psu.edu/fruit-harvest-determining-apple-fruit-maturity
Tong, Cindy. Check Apple Ripeness with the Starch Iodine Test. Aug. 29, 2018. UMN Extension. https://blog-fruit-vegetable-ipm.extension.umn.edu/2018/08/check-apple-ripeness-with-starch-iodine.html