How to Grow Blueberries
Who won’t like to grow fleshy, juicy blueberries in their yard? Blueberry bushes have some big advantages of living and fruiting for 40-50 years and being resistant to most pests and diseases. Moreover, they can give fruits for as many as 20 years.
They are beautiful to look at too with crimson fall foliage and bell-shaped, milky-white spring flowers, so can be a spectacular addition to one’s landscape. These are only a few of the many reasons one should grow blueberries in their garden.
Published: August 14, 2020.
One may be surprised to know that people started growing blueberries just in the 20th century. Before that, they enjoyed these delicious fruits native to North America by finding them in the wild. Then researchers found ways to cultivate blueberries.
Blueberry bushes range from 3 feet to 15 feet in height and from 4 feet to 10 feet in width. Flowers are small, creamy white, bell-shaped, and bloom in late spring in the form of hanging clusters. Leaves of the bush are oval-shaped and pointed, and are leathery to touch. During the fall, they turn bright red. Berries are first green and then as they ripen, they turn purple-blue.
Types of Blueberries
Blueberries are of four types:
- Hybrid half-high
Highbush is the most commonly cultivated blueberry type. This species has gone through most blueberry breeding experiments. Hence the varieties range widely in size and flavor of the fruit, and fruiting season and cold hardiness of the plant.
Growers can harvest more and bigger berries by planting two or more varieties of blueberries together because blueberries are only partly self-fertile. Planting multiple varieties has another benefit of extending the harvest season. Here are some recommended varieties of blueberry.
Lowbush (Vaccinium angustifolium)
Lowbush blueberries withstand the coldest climates and are hardy for Zones 3 to 7.
The blueberries found in supermarket shelves in cans are actually this variety. When they are fresh, they taste sweet and are covered with a waxy tinge which is so thick that the berries look sky blue or gray.
Creeping plants that are around a foot tall are spread by underground stems or rhizomes. They are found in the Northeast and nearby areas covering the rocky upland soils.
Plants available in nurseries are often seedlings or unnamed wild plants, and not named varieties.
Highbush (Vaccinium corymbosum)
This is a 6-foot shrub hardy for Zones 4 to 7. It can again be classified into Northern Highbush and Southern Highbush. The Southern Highbush is less cold tolerant and thus, is ideal for warmer climates. Here are its sub-varieties.
- Meader, Jersey, Herbert, Blueray or Bluecrop: These withstand cold winters.
- Herbert, Darrow, Coville, Blueray, Bluecrop or Berkeley: These produce big berries.
- Wareham, Stanley, Pioneer, Ivanhoe, Herbert, Darrow or Blueray: These produce berries that have a great flavor.
- Pink Lemonade: These produce bright pink blueberries.
- Earliblue, Collins: Early-season
- Blueray, Berkeley, Bluecrop: Mid-season
- Patriot, Jersey: Late-season
Half-high blueberries are the resultant of breeders’ efforts of combining the qualities of lowbush like low stature and hardiness and highbush blueberries such as heavier fruiting.
Northcountry is a variety developed by the University of Minnesota. It grows 18 to 24 inches tall and gives very nice, mild-flavored, lightly aromatic sky-blue berries, whereas Northblue grows 20 to 30 inches tall and gives abundant nickel-size dark blue, slightly tart fruits that are just apt for making pies.
One more half-high is Northland. It grows 3 to 4 feet tall. It’s from Michigan and has relatively bland, ordinary-quality fruit.
Varieties Ideal for the South
These are hardy for Zones 7 to 9.
- Rabbiteye (Vaccinium virgatum): Rabbiteye is grown throughout the southeastern United States. It’s tolerant to extreme heat and also to less-than-perfect soil conditions. The sub-varieties of this variety are very much adaptable, prolific, and pest-resistant. However, they have a high level of self-incompatibility and need two or more varieties to be planted together to ascertain pollination. Their recommended varieties are Brightwell, Woodard, and Powerblue. Other recommendations are:
- Tifblue: Standard
- Woodard, Climax: Early-season
- Southland, Briteblue: Mid-season
- Delite: Late-season
- Southern Highbush (hybrids of V. darrowii, V. corymbosum or V. virgatum): A cross between Rabbiteye and Highbush, these tend to be harder to grow and fussier than rabbiteyes, but there are some high-quality varieties that excel, such as Springhigh, Windsor and Emerald.
- Southblue, Onreal: Early-season
- Sunshine Blue, Jubilee: Mid-season
When to Plant?
Blueberry bushes should be planted in early- to mid-spring.
Preferably, 1- to 3-year old plants should be chosen. They are available in containers or bare-root. Older plants tend to get transplant shock and may take a few years more to start producing big harvests.
In any case, one should buy them from a trustworthy website or nursery.
Choosing and Preparing a Planting Site
One should choose a sheltered, yet sunny location. Although blueberries can tolerate shade, the sun gives better crops. Growers should make sure that the plants will receive direct sunlight at least for ¾ day. Also, the spot should not receive harsh, drying winds.
One should not plant blueberries right next to trees, because trees will not just block sunlight, but will also absorb any moisture in the soil.
If grower plans to grow multiple bushes, they should plant them in a patch, instead of scattered all through the yard. Planting in a patch will boost berry production in quality and quantity.
Blueberry, being a shallow-rooted plant, needs a soil that can hold moisture but has a good drainage and doesn’t stay wet. So, growers should avoid spots that have heavy, clayey soil that stays wet. Also, they should avoid spots where water stands for 2 days or more.
Blueberries thrive well in acidic soil. The pH of the soil should ideally be in the 4.0 to 5.5 range. Thus, growers should first do the soil test from their local country extension office. If the soil is not acidic enough, the growth of the plant will be stunted. This problem can be solved by mixing a small quantity of granulated sulfur in the soil several months before planting. Even pine needles or bark as well as peat moss are great additions that will help growers acidify their soil.
However, the grower shouldn’t depend only on them because they alone cannot sufficiently acidify the soil. Therefore, growers should use sulfur which is an organic soil acidifier. Sulfur comes in powdered as well as granulated (pelletized) form. The powdered form is usually expensive and can be risky to use because it creates a very fine, breathable dust. On the other hand, the granulated form is less expensive and safe to use.
The sulfur packaging will describe how much the grower should add to achieve the right pH in relation to the existing pH found out by the soil test.
Growers should also take their soil type into consideration. E.g. sandy soil will need considerably less acidifier than clay soil.
To identify the soil type, one should clench a handful of their soil in their fist. If it breaks quickly, it contains mostly sand, whereas if it forms a firm globule, it’s clay- or silt-based soil. On the other hand, if the soil comes together in one’s fist but falls apart easily if they press their finger on it, it’s a loamy soil.
Once the soil type and amendment quantity are identified, the sulfur should be spread over the soil where growers plan to plant their blueberries. As they dig the planting hole, the sulfur will mix with the soil.
Growers should make sure they keep on amending the soil to reduce its pH periodically because soil tends to return to its original pH. Also, they should remember that it takes time for the soil pH to change. Roughly it’s ideal to start amending the soil in the fall. Spring is also not too late. Then again growers should retest the soil right before planting to make sure if they have achieved the right results or not.
Apart from acidic soil, blueberries love soil that is consistently moist, well-aerated, and high in organic matter. Most gardeners think of compost when it comes to organic matter. They love compost. However, in the case of blueberries, compost is actually detrimental because although blueberries want a lot of organic matter, they don’t like a lot of nutrients. Since compost is packed with nutrients, it should not be added to blueberries’ planting site as organic matter. For the same reason, farmyard manure also should be avoided because it’s too rich for the plants and can scorch their fine, fibrous roots.
Instead, growers should use peat moss. It’s long-lasting (breaks down slowly) and has fewer nutrients. Once growers dig planting holes, they should add peat moss to the soil dug from the hole (which further will be mixed with sulfur too if needed). The quantity doesn’t need to be a specific one. It should only be generous, e.g. a bucketful. Once the plant’s root ball is set in place, the grower should backfill the hole with the mixture of soil, peat moss, and sulfur. Sulfur will lower the soil pH and the peat moss will aerate the soil in addition to providing a good amount of low-nutrient organic matter.
What if the Soil is Alkaline?
If growers find that their soil is not acidic by just a few pH points, but is very highly alkaline, there are still hopes for them to grow blueberries. Here’s what they should do:
- They should dig an area around 3 to 4 feet in diameter per plant and 2 feet deep.
- Then they should remove all the existing soil in that area.
- Next they should add a mixture of non-native well-drained soil and half peat moss.
- And now they should plant their bushes in this new soil.
How to Plant?
Growers should dig around 20-inch deep and 18-inch wide holes (or just around twice as deep and as wide as the length of the roots). As mentioned above, they should add peat moss to the soil dug from the hole (which further will be mixed with sulfur too if needed). Now the bush should be set in the hole with its roots spread out. It should never be planted any deeper than it grew in the pot if the grower has bought a container-grown plant.
Once the plant’s root ball is set in place, the grower should backfill the hole with the mixture of soil, peat moss, and sulfur.
Growers should keep a space of 4-5 feet between bushes in a row and at least 8 feet between rows.
While planting blueberries in rows, growers should consider “hilling” the bushes i.e. they should raise them above the ground level by 12” to 18” high and 3' wide. This will improve drainage and growers can conveniently add organic matter constantly.
Not at the time of planting but one month after that, fertilizer should be added because roots of plants that are still to establish are sensitive to salt. ½ ounce of a 10-10-10 fertilizer should be added in a strip around the plant 6 to 12 inches from the crown.
NOTE: Some gardeners recommend not fertilizing blueberry plants until they are a few years old and after that, providing them only organic feeds such as soybean meal or similar feeds and no other fertilizer (given below).
Growing Blueberries in Containers
Growing blueberries in containers is in fact more convenient than growing them in the ground. Pot-grown blueberries are more disease-resistant, easier to protect from birds and other thieves, easy to harvest, and of course, growers can move them whenever and wherever they want. In addition, if growers live in an area where there is no acidic soil, growing blueberries in containers allows growers to adjust the soil pH particularly for them.
How to Plant
- Growers should choose a large container with drainage holes
- They should choose a potting mix created for acid-loving plants like rhododendrons or azaleas. Or they can mix sandy soil and peat moss.
- Now they should plant the bush in the container and water profoundly
- Then they should add mulch on top of the soil to preserve moisture
- They should place the pot in a sunny location
- They should keep the soil moist
- If growers live in the northern region, they should overwinter the blueberry container in a protected space or wrap it in burlap or cover it with straw
- Experts recommend changing the soil in the container regularly, ideally every 1 to 2 years to keep the bush healthy.
Some varieties suitable for container-growing are:
- Pink Lemonade: These are pink-colored blueberries that contain genes from rabbiteye blueberries. They are suitable to almost all types of climates.
- Pink Champagne: This is another pink variety. It’s packed with antioxidants and is sweeter than blue-colored blueberries.
- Top Hat: This variety has been bred by the University of Michigan for containers or small spaces.
- Some dwarf varieties to grow in containers are:
- Dwarf Northblue: Mid-season, grows up to 20-24 inches
- Dwarf Top Hat: Late-season, grows up to 18-20 inches
Taking Care of Blueberry Bushes
Growers should perform a soil test at least every two years to check when to re-acidify the soil. Soil amendment with sulfur will reduce pH only temporarily. Over time, however, the soil starts returning to its native pH level.
Growers should mulch the bushes to keep their shallow roots moist and protected from weed competition. Mulching keeps the soil insulated against weed germination and dry air. They should apply a 2- to 4-inch layer of sawdust, pine needles or woodchips around the bush after planting it. Such organic mulch breaks down over time and improves the soil for the blueberry bushes. However, the mulch should be a little away from the trunk of the bush to permit good airflow.
Growers should give their blueberries 1 to 2 inches of water per week. Drip irrigation is the best method for all types of shrubs because it provides water at a slow rate in low amounts, which plant roots can absorb the best.
Discouraging Fruiting for Initial Years
Growers should not allow the bush to fruit for the first couple of years after planting. This will let the plant use its energy to establish well in its new home. Growers should remove any flowers blooming on newly planted bushes to direct the energy towards the plant’s growth.
There is no need to prune blueberry bushes for roughly around the first 4 years after planting. Thenceforth, the plant requires pruning to stimulate the growth of new shoots that will produce fruits the next season.
Growers should prune plants in late winter or early spring before the beginning of new growth.
Broken, dead, weak, spindly, and short shoots should be cut out.
While working on highbush varieties, growers should start with large cuts and remove wood that is more than 6 years old, crowding the center of the bush or dropping to the ground. They should also remove low-growing branches, the fruits on which will touch the ground, and also spindly twigs.
While pruning lowbush varieties, growers should cut all stems to ground level. Pruned bushes won’t bear the season following pruning. Therefore it’s a good idea to prune a different half of a blueberry patch every two years (or a different third of a patch every three years).
While blueberry bushes don’t like a lot of nutrients, they do need some nutrients. If growers use organic mulch around them, it will break down over time and provide some nutrients to the bushes. However, blueberries will need and benefit from a small quantity of nitrogen. For this, it’s recommended to apply alfalfa meal, cottonseed meal, or soybean meal every year.
These meals provide a fair dose of organic nitrogen without overdoing it. A good rule of thumb is to apply two pounds of meal per 100 sq. feet of blueberry bushes.
This is the only nutrition maintenance routine blueberries need. Once it’s done, they will withstand late frost, drought or any other challenges.
Pests and Diseases
Birds love blueberries a lot. Hence growers should make sure they drape bird netting over their plants ahead of time. Growers can also encase their entire blueberry patch in a netted cage.
If growers have a large blueberry garden, they should consider using a bird deterrent. This sends out a bird in distress call which keeps birds away.
Spotted Wing Drosophila (SWD)
This is a kind of fruit fly and commonly affects blueberries. While most fruit flies are attracted towards overripe fruit, SWD is drawn to under-ripe fruit. SWD is relatively new to the US and bait traps are being developed for this pest. Till then, growers troubled by SWD can avoid them by planting early-ripening varieties as SWD doesn’t attack until early August.
Blueberry Maggot (Rhagoletis mendax)
Another blueberry pest one should beware of is the blueberry maggot which is a small fly-like critter that keeps flying around blueberry bushes. An easy and organic solution are traps.
They are attracted towards the red or green color so, gardeners can use any red or green orb which one can buy at home or garden improvement stores and then treat the orb with Tangle Trap, a sticky substance that one can coat the orb with. However, one should be very careful while applying the Tangle Trap because it’s extremely sticky and is very difficult to get rid of should it get applied to one’s fingers. Such orbs should be hung among the blueberry bushes. The flies will stick to them and die.
If the gardeners are worried about any maggots living inside their blueberries, they should refrigerate the berries for at least 48 hours before consuming them. The freezing will kill any maggots inside the berries. It may sound disgusting, but the berries are still tasty and safe.
Also, one can submerge berries in a mixture of a cup of water and a teaspoon or two of salt. If there are maggots inside, they’ll crawl out.
These yellow-necked caterpillars covered in long white hair and with a large yellow band around their neck sometimes occur on blueberries and can be easily spotted. They eat the leaves and become even more visible. Spraying an organic insecticide is the solution. But gardeners should take care of not killing other beneficial insects in the garden.
Common fungal diseases that affect blueberries are powdery mildew and leaf spot diseases. The best strategy to fight them is choosing resistant varieties. Giving the plants ample space for good air circulation and full sun, cleaning up any fallen debris and replacing the mulch every year also helps. Even then, should the fungi occur, growers can use a fungicide recommended for using on edible plants.
Some other common diseases that can affect blueberry include:
- Botrytis: This is a fungal disease that spreads quickly in damp weather. It causes the fruit to wither and rot.
- Anthracnose: This is another fungal disease that thrives in damp conditions. Its symptom is bright pink masses of spores on developing berries.
- Mummy berry: This is a kind of more serious blueberry disease. It’s caused by a wind-borne fungus named Monilinia vaccinii-corymbosi starting with blackening of flower clusters that ultimately die. The spores can also affect the other blossoms. Resulting fruit becomes hard and tan, looking like mummified berries. However, growers don’t need to worry a lot about this disease as they can just remove and discard as many of the mummified berries as possible and avoid further spread of the disease. The mummified berries should not be added to the compost pile.
Then at the end of the season, a thick layer (1”-2”) of mulch should be spread around the base of the bushes to cover any of the mummified berries that are missed. Once they are covered, the fungal spores cannot spread and the next year’s crop should be safe. It’ll also have the benefit of a fresh layer of insulation and the mulch will break down to improve the soil.
- Canker [Fusicoccom (Godronia)]: This starts developing in the lower parts of the canes. Small reddish spots start appearing that will become bigger like bulls eye. If they are not treated, they’ll girdle the cane causing it to dieback.
- Twig blights (Phomopsis): These are quite similar to canker and as they progress, they can even affect the crown, smaller branches and twigs, and also cause leaf spotting.
Insects that can harm blueberry bushes are cherry fruit worm, plum curculio, blueberry tip borer and cranberry fruit worm. If these are common to the growers’ area, they should inquire with their local extension for recommended treatments and deterrents.
Chlorosis (yellowing of leaves): Chorosis or yellowing of leaves is quite common for blueberries. While it’s typically an indication of iron deficiency, it’s perhaps not caused by a lack of iron in the soil. A more likely cause is too high soil pH due to which the plants cannot access the iron already present there. If one sees yellowing continuing, they should get their soil pH tested and make amendments accordingly.
If growers plant 2-year old bushes, they should begin fruiting within a year or two (however, growers should remove any flowers the first couple of years after planting to let the bush establish itself well). Growers should keep in mind that only after 6 years, there is full production (depending on the variety chosen).
Blueberries are usually ready for harvesting between June and August. While choosing varieties, growers should check their ripeness period and select a mix of varieties that ripen early, mid and late in the season; thus they can enjoy blueberries all summer long and even in the fall.
Growers should not rush to pick the berries right after they turn blue, but should wait for at least 4-5 days more. When they turn blue, they have started ripening but are not totally ripe. When the berries are totally ready, they should fall off right in growers’ hands. This can be identified by tickling the berries very gently as suggested by experts.
Perfectly ripe berries fall from the stem with this gentle touch, while unripe berries don’t and remain attached. Growers will have to continuously keep checking their berries in the warm summer days to avoid missing perfectly ripe berries that may fall to the ground.
Blueberries are extremely easy to freeze. Freezing blueberries allows growers to enjoy them year-round. Freezing them should be done properly in order to avoid the formation of one giant clump of all the berries.
Once growers finish picking the berries, they should bring them in the house and spread them out on cookie sheets. They don’t need to be rinsed (they can be rinsed once taken out of the freezer); they just need to completely dry. If there are any stems and leaves mixed with the berries, they should be cleaned.
If growers properly dry berries by spreading them on cookie sheets, they will freeze individually and won’t form a big clump. Then users can take the amount they want. On the other hand, if they are just kept for freezing in freezer bags, they mush and clump together. Instead, growers should first freeze them individually in the above way and then put them in freezer bags. They can even be put into bowls. Blueberries stored in this way can be used for the entire year, as a tasty snack on their own or added to recipes.
Growing blueberries can be an extremely enjoyable and rewarding experience since the plant is easy to grow, maintain, and harvest. By taking due care, one can have these delicious and healthy fruits for years to come.