Quick Summary: Blueberry sweetness depends on variety, potassium levels, and growing conditions. Half-high varieties like St. Cloud and highbush varieties like Bluecrop tend to be the sweeter varieties for the Midwest. Use a high-potassium fertilizer during fruiting, avoid overwatering, and let berries fully ripen before picking. Read time: 8 min | Experience level: Beginner to intermediate
Jump to: Best Blueberry Cultivars for Sweetness | Potassium for Sweetest Berries | Growing Tips for Sweetness | FAQ
Blueberries were the very first specialty crop I grew for the St. Paul Farmers’ Market back in 1998. I planted 600 blueberry plants on our 23 acres at HeathGlen farm and paid special attention to which varieties or growing conditions yielded the sweetest berries.
This guide covers which cultivars tend toward sweetness, how to fertilize for better flavor, and the growing conditions that help your berries develop the sugar content you’re after.
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Which Blueberry Varieties Are Sweetest?
Before we get into how to grow the sweetest blueberries, it’s important to consider the different types of blueberry shrubs out there. How sweet your harvest will be depends a lot on the type of blueberry plant you go for!
There are four basic types of blueberries:
- Half-high blueberry plants ( cross between highbush and low bush)
- Highbush blueberry plants (Vaccinium corymbosum)
- Lowbush blueberry plants (Vaccinium angustifolium)
- Rabbiteye blueberries (Vaccinium virgatum)
Half-High Varieties
Our farm, HeathGlen Organic Farm, is in zone 4, bordering on zone 5. My initial research showed that the half-high plants were considered sweet and adapted for a zone 4 climate.
Based on this research, we planted 500 half-high blueberry bushes in 1998, and they are still thriving more than 25 years later. Our mix included Polaris, Northblue, St. Cloud, Northland, and Chippewa.
As far as sweetness goes, St. Cloud is considered one of the sweetest half-highs (smaller berries however).
Friendship (a Wisconsin variety) is more similar to the tarter flavor of wild blueberries.
I put together the video below which goes over the characteristics of the hardier blueberry plants that grow well in Northern climates.
High Bush Varieties for the Midwest
The climate has changed a bit since 1998 and the number of cultivars have expanded, so we have added quite a few high bush varieties to the mix over the years.
Bluecrop has been the sweetest high bush variety that grows successfully on our Minnesota farm. It is considered a main-season variety, with fruit that we typically harvest the second week in July.
Duke is another high bush variety we grow that is on the sweeter side. It is a later variety that is harvested starting in late July.
The plump blueberries you’ll find in your local grocery store usually come from a highbush variety. This is the more commercially available variety, which has been selectively bred for factors like berry size, sweetness and shelf life.
Lowbush Blueberry Varieties
Lowbush blueberry cultivars aren’t as extensively bred as their highbush cousins. Most often when people talk about picking wild blueberries, they are talking about berries from the lowbush blueberry plants
Wild blueberries tend to be smaller and generally quite tart. Perfect for baked goods, but not as sweet for eating out of hand.
Tip: If you want to grow your blueberries in pots or containers I would stick with the half-high varieties. Some of the high bush varieties grow to 6-7 feet tall which is cumbersome in a container.
Rabbiteye Blueberry Varieties
Lastly, popular for warmer areas due to their better heat tolerance, rabbiteyes are another good choice if you like sweet blueberries and live in a warmer climate. The skin on these relatively large fruits is a bit thicker than that of most highbush plants.
Some scientific studies suggest rabbiteyes are actually even sweeter than many highbush cultivars, but others don’t agree. It might just be a tie between the two, depending on the exact cultivar you go for.
All this being said, there are many more things to keep in mind when it comes to blueberry sweetness. In addition to the cultivar you choose, the sweetness factor may depend more on the growing conditions than on the specific variety.
Why Potassium Is the Key to Sweet Blueberries
In my years of growing this fruit, I’ve learned that there’s one factor that influences blueberry sweetness more than any other. It’s potassium! In fact, this humble mineral is one of the most important in ensuring any fruit tastes good.
Basically, when plants like blueberries enter the ripening stage, their potassium use soars. Potassium helps ensure the fruit ripens at the right pace, acquires the right color and takes on its typical flavor.
Most importantly in this case, it also plays a huge role in the eventual sugar content of your blueberries.
To help make sure your harvest doesn’t turn out tart or bland, try using a special blueberry fertilizer. It should be high in potassium (the K in the N-P-K ratio, which stands for potassium), and will usually also contain elements that help acidify the soil, which is just how blueberries like it.
You can apply fertilizer on a regular basis from mid-spring onward. It’s especially important to keep up with your fertilizer schedule once your blueberry shrub has begun blooming and developing fruit.
Growing Tips for Sweeter Blueberries
Aside from potassium, there are a few other important things you should keep in mind if you’re wondering how to grow the sweetest blueberries, which should include:
- Water: Although your blueberry bushes will need plenty of water – about an inch per week – too much moisture can negatively affect berry sweetness. Blueberries tend to grow huge during wet years, but they may also be bland.
- Sunlight: Although they’re not necessarily fans of very high temperatures, blueberry shrubs love growing in full sun. Their fruit production can be affected if they don’t get enough light.
- Soil acidity: Blueberry shrubs like their soil nice and acidic, with a pH of 5 or under. If your soil is more alkaline, you may have to use an acidifying amendment to avoid issues.
- Harvesting: For the best flavor, you should leave your blueberries on the plant until they’re fully ready to pick. You can find out more about pinpointing the perfect moment in the post on how to tell when blueberries are ripe.
FAQ
Among half-highs, St. Cloud is considered one of the sweetest, though berries are smaller. For highbush, Bluecrop is reliably sweet. Friendship tends toward tart.
Most likely a potassium deficiency, overwatering, or picking too early. Blueberries need high potassium during ripening to develop sugar. Wet years produce large but bland berries, and picking berries that are not fully ripe will yield tart berries.
Apply a high-potassium blueberry fertilizer from mid-spring through fruit development. The ripening stage is when potassium demand peaks.
Acidic soil (pH 5 or below) helps blueberries absorb nutrients properly, which indirectly affects sweetness. Alkaline soil can cause nutrient deficiencies that impact flavor.
Either works. For containers, stick with half-high varieties that stay compact. Highbush varieties can reach 6 to 7 feet tall and become unwieldy in pots. Overwintering correctly is the key to successfully growing blueberries in pots.
Fully ripe berries are deep blue with no red or green at the stem end, and they detach easily with a gentle tug. Leaving them on the bush until fully ripe maximizes sweetness.
In addition to tasting great, blueberries are known for their health benefits. There are however, a number of myths around the health and growing of blueberries. This article will help you parse the myths around blueberries.
Now, what are you going to make with all of those fresh blueberries? For 80+ recipes that highlight blueberries (sweet to savory recipes), check out my blueberry cookbook on Amazon ($28.75), or get the pdf (ebook) here for $14.95
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Breathtaking blueberries!!!
🫐 These blueberries are so healthy and ripe and a beautiful color!!!!❤️
Yes, they’re wonderful little jewels aren’t they? This year I’m trying to up my game with raspberries and strawberries, but nothing beats the blueberries.