Crops

When and How to Fertilize Blueberries for the Best Results

Published:

December 23, 2024

Key Takeaways

Blueberries need loamy, acidic soil with a pH of 4.3–5.5. It’s essential to conduct a soil test in advance to adjust conditions before planting if needed and maintain the right acidity afterward.
Nitrogen-heavy fertilizers, such as ammonia or urea, are the most suitable for blueberries, although it’s still important to avoid excessive amounts to prevent harm.
If you use slow-release granules, apply them evenly around the plant base, and avoid over-tilling the soil. If you use a liquid fertilizer, remember that they are easy to overuse.

Blueberries are an excellent addition to farms of any size, whether it's a backyard garden or a commercial operation. They are delicious and highly nutritious, selling well on the market; they also freeze extremely well for long-term storage or shipment.

Blueberry bushes are also fairly hardy and easy to raise, with variations that can thrive in almost any North American climate zone. However, the size and quality of berries will vary greatly depending on the overall health of the plant. Blueberries need very specific soil conditions and fertilizing for best results.

So, in this guide, we'll look at the most common blueberry fertilizer recommendations, soil conditions, and timing to produce the best possible berries!

Start With a Soil Test

If you're serious about getting your blueberries off to a good start, step one is to select the right soil and test it to ensure the conditions are right. Do this around six months before planting, so you have time to adjust the soil.

The soil should be loamy sand, which will hold some moisture but quickly drain so that the plants don't drown. Do not attempt to plant blueberries in clay or similar soils. More water available to the blueberry bushes will result in larger, juicier berries.

The most important factor is acidity. Blueberries want high acidity in the soil, with an ideal pH around 4.3–4.5. They can still survive and produce fruit when the pH is up to 5.5. However, the less acidic the soil, the smaller the overall yield will be.

If the pH is too high, add acidic fertilizer such as ammonia to get it into the right range.In addition, the soil should be biologically active, with plenty of leaves, compost, and other organic material. However, avoid manure, which can damage the blueberry plants.

Once the soil is in good shape, you'll be ready to plant your blueberries and get going.

When to Feed and Fertilize Blueberries

Depending on your climate zone and the plant’s species, highbush Blueberries can potentially be planted during almost any time of year. However, it's most common to plant them in early spring, which is what we'll focus on in this guide. If you plant them in a different season, adjust the fertilizer schedule accordingly.

In addition, do not fertilize your blueberries at all for the first year. Their root system is too weak and will be harmed. Many don't add fertilizer until years 3-4, but it’s important to monitor blueberry’s fertilizer needs in your particular fields.

Early Spring

The first round of fertilizer should be added once there's new plant growth but before the buds open. Keep in mind that blueberries grow quickly and can go from seed to harvest in as little as two months.

Midseason / Late Spring

Around five to six weeks after the first round, once berries are growing on the bush, it's time for the second round of blueberry bush fertilizer. This supports the growing berries and ensures the plant has plenty of nutrients to put into them during their final weeks of growth.

Post-Harvest

Blueberry bushes are perennial, and can potentially live for decades if properly cared-for. So after harvesting the berries (likely in June or July) add another round of fertilizer so the bushes can recover quickly and be ready to produce more berries sooner.

Choosing the Best Kind of Fertilizer for Blueberries

In general, you want nitrogen-heavy fertilizer because, for blueberries, extra acidity is a requirement. It's best to use ammonia- or urea-based fertilizers. Nitrate-based fertilizers can injure the plants' roots and inhibit growth.

The other thing to keep in mind is that blueberries evolved to grow in nutrient-poor soil. So a light touch will be needed in fertilization. Too much fertilizer will harm the plant.

Otherwise, what fertilizer to use will depend on your goals; let’s review the most common ones.

Lowering pH

Again, at the risk of overstating the point, acidity is the most important factor when growing happy healthy blueberry bushes.

The simplest and most common option is to use ammonium sulfate. However, be very careful about the amount — too much will quickly harm the plant. Also, as ammonium sulfate fertilizer is artificial, it will prevent the berries from being considered organic, if that's an important factor to you.

Elemental sulfur is another option. This is all-natural and organic, and there's less risk of scorching the roots. Just keep in mind that this is slower-acting than liquid fertilizers.

Do regular soil tests to ensure the pH is still in the right range.

Adding Nutrients

If the pH is basically good but your blueberries actually do need more nutrients, you can turn to regular NPK fertilizers. Of these, phosphorus is most important for producing big delicious berries.

Otherwise, look for standard 7-7-7 or 4-3-4 fertilizer blends. If you can't find blueberry-specific fertilizer, blends intended for azaleas or rhododendrons will work well. Cottonseed meal would be another good option for providing the necessary nutrients.

Just don't overdo it. Blueberries will be quickly harmed by soil that is too rich in nutrients.

How to Feed Blueberries Properly

Good fertilizing techniques will help ensure the nutrients make their way into the plant efficiently. When using slow-release granules — which are generally better than fast-acting liquid fertilizers — they should be sprinkled around the entire base of the plant. Go from the stem to the outer edges of the leaf cover. The granules should be spread as evenly as possible.

Do not turn or till the soil too much when adding fertilizer. This is unnecessary, as blueberries have shallow roots. In addition, doing so can harm the soil's biological activity, and you need a mycorrhizal fungal network growing alongside the roots to support them.

If you feel the need to get the fertilizer off of the surface, such as concerns about runoff, gently press it into the soil. But it should never go more than about an inch deep.

Should you use a liquid fertilizer, just follow the package directions. However, remember that such fertilizers are very easy to overuse and shock the roots. They should only be a last-ditch option for malnourished plants.

Additional Tips

To grow blueberries with the best results:

It’s typically recommended not to fertilize blueberries in the first year, but to let bushes grow naturally.
Mulching after adding fertilizer can help, especially if you're concerned about holding the soil's temperature (blueberries typically prefer warmer conditions) or intruding weeds. However, as with other aspects of feeding blueberries, use a light touch. Too much mulch will choke out the plant.
Prune your bush aggressively. It's entirely acceptable to prune up to 1/2 of the overall wood each year to make room for new blooms and fruit.
Keep watch on the leaves. If they turn red or pale green, that's a sign that either the soil pH is too high, or they are lacking nutrients.

When you have questions, we'll help you find the answers you need to take control of your fields and the harvest you care about. Contact Cropler to discover more about our products and the ways we help you proactively protect your operations from the effects of crop diseases. Learn More

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