How To Grow Organic Blueberries?
BITS ABOUT BLUEBERRIES
- Maine leads the US in growing wild blueberries commercially; approximately 25% of all commercially grown blueberries.
- In Maine, growing blueberries requires over 50,000 beehives – about 2 billion bees – just to pollinate the blueberry blossoms.
- Cranberries, Bilberries, Huckleberries, and Blueberries are in the same family.
- Growing organic blueberries (and eating them, of course) may lower the risk of heart disease, according to the British Journal of Nutrition in 2008 – after completing a study on pigs!
WHEN TO PLANT BLUEBERRIES
- The best time to plant blueberries is 10 years ago. However, if you didn’t, now is a good time (now being early spring).
- As blueberries originated as a woodland bush (low bush varieties include the wild blueberry of Eastern U.S. and Canadian forests and the huckleberry in the West), they resemble a small tree or bush more than a garden plant.
- When you plant blueberries, it takes between 8 and 10 years to reach full production, somewhat like a fruit tree. You’ll get some berries by the 3rd or 4th year after you’ve planted them.
- You can prepare your garden for blueberries in the fall or early spring, but it’s best to plant in early spring. However, if you’re adding fresh manure to the soil, do that in the fall.
WHERE TO PLANT BLUEBERRIES
- Blueberries like to be planted where they get lots of full sunlight, but they can handle some shade too. Too much shade, though, will reduce your crop yield.
- If you’re in a hot area, shade during the heat of the day may be desirable.
- Blueberries grow best in soil that drains well and where there is good air movement. Poorly draining soil will stunt the plants and reduce yields.
- If you live in an area with late frosts, select a late flowering variety as frost will kill blueberry flowers.
- Blueberries prefer areas that have acidic soil; this emulates their native forest areas which tend to be acidic.
- High calcium levels in soil are not good for growing blueberries, so check your calcium levels before you plant blueberries.
PREPARING THE SOIL
- As mentioned above, blueberries like acidic soils; a pH level of 3.8 to 5.5 is desirable – 4.5 is ideal. Blueberries don’t do well at levels above or below these levels. If your levels are too high, apply sulfur to your soil until it comes down to the range blueberries need.
- To prepare your soil, mix in heavy amounts of compost and/or composted manure into a 12 x 12 inch area, preferably at least 12 to 18 inches deep.
- Once you’ve enriched the soil, it is unlikely that you’ll need to fertilize much as blueberries are light feeders.
- Blueberry plants are long-lived (30 to 50 years or perhaps even longer), so considerable time and effort in preparing the planting site is a wise investment.
- If you have unlimited supplies of compost, manure, or composted manure, the most ideal soil prep would be to add about 4 to 6 inches over the entire area, then rototill or otherwise turn it into the soil.
- Other good soil additives for blueberries included rotted sawdust, peat, chopped leaves, horse manure, or rotted grass clippings.
- Organic matter helps the blueberry plant roots to absorb nutrients and water from the soil.
- Test your soil’s acidity levels annually to make sure it stays optimal for blueberry production.
CHOOSING THE BEST VARIETIES FOR YOUR AREA
- Choose two varieties or more for your blueberry patch. Cross-pollinating blueberries creates bigger and better berries.
- Check with your local county extension to see if there are diseases that afflict blueberries in your area. If there are, get recommendations for varieties that are resistant to those diseases.
- There are some new dwarf blueberries that can be planted in containers. Talk to a reputable supplier about procuring some of these varieties if you want to grow potted blueberries.
- Some variety names we’re aware of are Sunshine Blue (Southern Climate Zones), Northsky, Bluecrop, and Earliblue (these last three are Northern Climate Zone berries – don’t mix these up).
- If you plant in containers, a 5 to 7 gallon pot will be required for each plant.
- It will need to drain well, and a good potting soil with the proper pH level should work well.
- When you purchase blueberry plants, the roots will be bare. Fill your container about 1/3 full of soil, then, holding the plant where you want it, fill in around the roots with soil until the roots are covered up to the collar of the plant.
- After burying the roots, water the plant(s) well. Add a light mulch around the base of the plant such as bark or pine needles.
PLANTING BLUEBERRY PLANTS
- Blueberries are propagated with root cuttings. It’s rare to start them from seeds.
- What you’ll find available for planting is typically 2 or 3 year old plants. When you purchase these for planting, they’ll typically be “bare-rooted.” This simply means they’re not potted in soil.
- When you get your plants, you’ll want to soak them in cold water for about an hour.
- Separate the plants gently so as not to damage them.
- Dig your holes deep enough and wide enough not to cramp the blueberry plant roots when you place them in the holes.
- Back-fill the dirt around the roots, keeping them as naturally shaped as possible. Bury them to the same level as they were at the nursery.
- Mulch the berry plants with 3 or 4 inches of sawdust, peat moss, or barley straw after planting. Mulching keeps the soil moist, cool, and weed free.
- Plant your blueberry plants 3 to 4 feet apart in rows that are about 8 to 10 feet apart.
SUCCESSFULLY GROWING YOUR BLUEBERRIES TO MATURITY
- If you’ve prepared your soil properly as outlined above, most of the work is done.
- You do need to make sure you have lots of bees or other pollinators available for blueberry blossoms. You really can’t have too many bees. If you know any local beekeepers, invite them to place a few hives on your property.
- To encourage your berry plant’s growth, it is advisable to pick the flowers off your plants for the first couple of years.
- There’s no need to prune young blueberry bushes except to remove dead twigs or branches, or if there is an occasional obtuse branch that is weighting the plant down on one side (rare).
- In year 6, you can prune your blueberry bushes in the spring, but only lightly. Prune weak or dead branches or branches that are close to the ground.
- Leave at least 6 strong branches, but remove the rest. This will actually help the plants produce bigger and better berries and stronger shoots.
- It is a best practice to plant a cover crop such as rye-grass between your berry rows. It helps retain soil moisture and controls weeds and is less costly than straw.
- This past gardening season we tested a liquid organic leaf spray fertilizer called Organic Garden Miracle™. We sprayed most of our garden plants with OGM™. The sprayed veggies were more robust than the unsprayed plants, and the flavor was superior as well – sweeter and juicier. We’re excited this year to continue the experiment as we were impressed with the size and flavor of the garden crops we sprayed. We have a neighboring blueberry farm that will be testing OGM™ too. We know they’ll be impressed.
MULCHING AND WEEDING
- Two mulches were previously mentioned…organic mulches such as bark dust, straw, or grass clippings, or cover crops such as rye grass. Both help to control weeds, keep the soil moist, and keep the ground cool which is ideal for blueberries.
- Don’t use black plastic mulching around blueberries as they prefer cool soil.
- If you don’t mulch, you may rototill between the rows, no deeper than 3 inches and no closer than a foot from the plants.
- Even if you don’t mulch between the rows, it’s a good practice to mulch around your plants.
- Water blueberries weekly, no more than about 1 or 2 inches. Mulched soils need less water.
- If you over-water, you’ll risk your plants getting root rot infections.
- As with most crops, overhead watering increases risk of various diseases. Drip irrigation is ideal. If you don’t have that option, water early in the day so the plants can dry out by early afternoon.
- If your water is “sweet,” or alkaline, you may need to add sulfur to the soil around the base of your plants periodically. Consult your county extension on the best practices for maintaining your soil’s alkalinity.
COMPANION PLANTING AND ROTATION CONSIDERATIONS
- The best companion for blueberries is rhododendrons. They both love alkaline soil, the flowers can help protect the blueberries from afternoon sun, and they’ll attract more bees to your area.
- Heaths and heathers will accomplish the same thing, but not quite as well.
- Other acidic soil lovers include thyme, yew, pine trees, and grape hyacinth. All these do well with blueberries and rhododendrons.
- If you’re replacing a blueberry patch, it’s best either to rest the soil for a year, or move your patch to a location where there’ve been no blueberries for a few years. As blueberry bushes last up to 50 years or longer, though, this is an unlikely scenario for most gardeners.
- In our area, blueberries typically ripen in about mid-July. In the southern part of the state, it’s closer to the first of July.
- You’ll know if blueberries are ripe when they, well, when they’re blue! Oh, and when they taste sweet and juicy.
- The best flavored berries are allowed to remain on the bush for a few days after they appear ripe (but not too long). They’ll roll easily off into your hands at this stage of ripeness.
- The easiest way to tell when they’ve reached this stage is to eat one or two. You’ll know if they’re ready.
- After the first picking, you should be able to go back in 5 days or so and pick a 2nd picking, and possibly a 3rd as well, although the quantities will decline with each picking.
- We’ve stored unwashed blueberries in a sealed container in our fridge for up to 2 weeks successfully, although the quality tends to decline after the first week.
- Blueberries are best eaten fresh, but a close second is to freeze them in zip lock-type bags or plastic cartons.
- We mix them with some fresh goats milk (milk from the store is good too if you don’t happen to have a couple milking goats in your suburban backyard) and sugar and blend them to make delicious smoothies! The kids live on smoothies from July through the warmer weather.
- You can also make blueberry jam, jelly, pies, cobblers, crisps, syrup, cake or cookies. Blueberries are a wonderfully versatile fruit.
PREVENTATIVE AND NATURAL SOLUTIONS TO COMMON PESTS
- Blueberry Maggots are a fairly common pest. They like ripe blueberries (can you blame them!?).
- They come from a black and white fly that lays eggs in the ripe berries. The maggots eat the flesh of the fruit, then overwinter in the soil and repeat the process the following year.
- Tilling between the rows after harvest and allowing chickens to harvest the maggots is a good organic way to control these pests.
- If you have a large berry patch and a fairly heavy infestation, organic botanical insecticides such as rotenone or pyrethrum will control these pests, but they’ll also kill good insects.
- Diatomaceous Earth (DE) may also be effective, but it has to be dry. Once wetted, it has to be reapplied.
- The Blueberry Stem Borer is a beetle that deposits eggs that can damage new growth. The grubs will also bore into the canes and cause them to die as well.
- If you see very small pinholes along the stems with yellowish strings dangling from them, you likely have a blueberry stem borer attacking your plant.
- If you clip the wilted tips and destroy them, you’ll usually check this problem.
- The Cranberry Fruitworm overwinters in soil, matures to moth-hood in spring, and lays tiny, hard-to-see eggs on blooms and unripe fruits.
- After they hatch, the young larvae burrow into the stem end of the berries and web the berries together with silk.
- Keeping your patch free of debris reduces areas these pests can overwinter. DE or organic Bt (Bacillus thuringiensis) may be effective in controlling this pest, but Bt will also eliminate good insects, so decide carefully how this may affect your garden.
- The Cherry Fruitworm not only affects cherries, it also attacks and eats blueberries as well by boring a small hole and eating the inside of the fruit.
- The larvae overwinter on the bushes, mature into moths in the spring, which in turn lay eggs on the unripe blueberries. Once they hatch, the cherry fruitworm bores into the fruit as outlined above.
- Keeping your patch clean of leaves and pruned debris and rototilled will help reduce these pests. Planting away from cherry trees is also effective.
- DE and organic Bt may be effective against these pests if the infestation is heavy.
- The Japanese Beetle larvae develops in the soil below grass or lawns. In the early summer, the adult beetles emerge and feed on blueberry plants and berries.
- Keeping your patch free of fruit on the ground (harvesting cleanly) reduces rotting fruit that attracts these pests. Rototilling between the rows is also effective at keeping this pest away.
- If there aren’t too many of these pests, you can hand-pick them and drop them in a bucket of soapy water to drown them.
- Leaf Rollers are a caterpillar that roll up in leaves during their metamorphosis.
- The larvae feed on green or ripe berries and leaves, but rarely cause significant damage.
- There are parasitic wasps or flies that you can import (purchase the online or at your local garden center) that will parasitize the larvae.
- You can try DE, but apply frequently to keep enough powder available for the larvae to dine on. Organic Bt can also be used as a last resort and we recommend trying anything else as Bt will destroy beneficial insects as well.
- Leaf hoppers are small insects that hang out on the undersides of leaves or on stems. They suck the juices out of plant leaves and inject stunting microorganisms into the plant’s leaves.
- Insecticidal soap spray or DE have been effectively used by organic gardeners to control these pests.
- Aphids, a.k.a. “plant lice,” are relatives of the leafhoppers. They suck the juices out of leaves and reproduce rapidly.
- Aphids can be particularly damaging to blueberries as they transmit a virus known as the blueberry shoestring virus to blueberry plants and can cause a lot of damage via this virus.
- The best way to naturally control aphids is to introduce lots of ladybugs to your blueberry patch. Ladybugs are voracious diners on aphids.
- You can also use insecticidal soap sprays if your infestation is minor.
- Birds aren’t an insect, but they can really put a dent in your crop – literally. We’ve had them strip a cherry tree overnight, and they can strip a blueberry patch in short order.
- Using netting to cover your plants is effective if you don’t have too big of a patch. You’ll have to remove the netting when you harvest and after the harvest is complete.
- Rabbits like to eat young blueberry bushes, mostly in the winter. Enclosing your patch with a low poultry netting will keep these pests out.
- Mummy Berry makes the berries dry out before ripening. Removing dried and dead twigs and berries in the fall helps to reduce this fungal disease.
- Too much nitrogen in the soil, poor air circulation, and frost all exacerbate this fungus.
- Keeping your patch clear of debris is helpful, as is removing or burying mummified berries and plant debris.
- Botrytis Blight is instigated in wet or foggy weather. The blossoms or young shoots die, turn brownish-colors, and then get covered with a mass of gray fungus spores.
- Avoid high nitrogen levels before and during the bloom.
- Anthracnose is an infection which attacks the berries during wet and warm periods. You’ll see the infections attacking the blossom end of blueberries.
- When the ripening fruit is turning blue, the infected regions will sink slightly, making the surrounding areas looks puckered. Sometimes a layer of pink, slimy spores may develop on the infected regions.
- As with many blueberry diseases, avoid over-nitrification as too much nitrogen tends to encourage various diseases to develop in blueberries.
- Don’t allow your fruit to get overripe as anthracnose is more common on overripe blueberries.
- Removing dead wood in the fall or spring will reduce the fungus spores that cause anthracnose.
- Stem Blight appears as a reddening, browning, or wilting of infected leaves that often precede the death of your blueberry plant.
- Stem blight is a vascular disease that most often starts from an infected wound, often near the base of the plant.
- If the discoloration is high on the plant, cut below the infection about 12 inches and remove and destroy the infected branches. Ideally this should be done during the winter.
- Rust is mostly an issue with Southern cultivars (blueberry plants). You may at first see yellowish leaf spots in late spring or early summer, which turn a reddish-brown color later in the summer (yellow-orange pustules may be seen on the lower surface of the leaves), which subsequently turn brown and drop from the bush early.
- Clip any infected branches and destroy them, the earlier the better.
- Fusicoccum Canker affects the stem of the blueberry plant and causes branches to die back and the plant to lose vigor.
- Pruning bad branches and destroying them, and minimizing winter damage are the best treatments for this fungal disease.
- Shoestring Disease shows up as a red discoloration in the mid-vein of a leaf, making it wavy and distorted. There is no way we know of to control this disease except to control aphids which spread this disease. Purchase your plants from a reputable nursery whose plants are shoestring disease-free.
- Stunt is a disease that causes plants to lose vigor and become dwarfish and yellowed. It is caused by a virus carried by leafhoppers. Bushes with this disease must be removed immediately and the leafhoppers must be eradicated quickly so you don’t lose your whole patch.
- However, you’ll need to make sure to trap the leafhoppers in that bush so they don’t escape to a neighboring bush or that bush will contract stunt as well.
- Scorch Virus causes blighted blossoms, branch dieback, and crop reductions and can kill the plant. It is spread by aphids, so controlling aphids with ladybugs or Bt or insecticidal soap is imperitive.
- Planting virus-free stock to start with is also advisable, from a reputable nursery.
- Remove infected plants.