Image credit: Cornell University PMEP
Blueberries are delicious… oh and they are good for you! Rich in vitamins K and C and high in fiber content, they are the ideal edible plant for your garden. Native to our region, blueberries have adapted to New York's climate, soils and pests. They are not only easy to grow without chemical pesticides, they are extremely cold hardy with some cultivars that can survive in winters with temperatures as low as -40F.
Putting the effort into a little planning and preparation before you plant your blueberries will pay off with years of low maintenance plantings and plentiful harvests.
Start with the soil
Blueberries need soil that is well aerated, moist, high in organic matter, and very acidic. Before planting it’s important to test, at the very least, the pH of your soil. Blueberries need the soil to be between 4.0 and 5.5. Adjust pH, if necessary by mixing in sulfur, a natural mineral, the season before you plant your blueberries (it takes 2 months of warm weather for soil to adjust). Alternatives such as aluminum sulfate or ammonium sulfate can also be used. Mix the sulfur or aluminum sulfate into the top six inches of soil across the area of the entire mature root zone.
Add materials such as aged pine bark, leaf mulch, compost of any type (manure, garden waste, kitchen) to ensure good drainage. Sandy soils are preferred, but blueberries can thrive in clay soils if enough compost and organic material is worked into the soil ahead of planting. Acid materials like peat moss and pine needles make fine amendments to the soil but will not lower the pH enough.
Blueberries like company. They produce larger berries and bigger harvests when cross-pollinated with at least one other cultivar. Extending the harvest season is another benefit of planting more than one cultivar. Blueberries are divided into early, mid and late season varieties with different maturity dates. For pollination purposes choose cultivars that will have blooms that overlap. Bluecrop is a mid-season berry that can be paired for pollination with both late and early ripening varieties.
Before settling on specific varieties, you will need to choose the types of blueberries that are best suited to your garden: highbush Vaccinium corymbosum, lowbush Vaccinium angustifolium, half-high – a hybrid of high and low. Highbush varieties typically recommended for northern growers in zone 4-7 include Patriot, Bluecrop, Jersey and Blueray. Colder areas in Zone 3 should stick to cultivars with north in the name like Northblue, Northcountry and Northland.
Whether grown in the ground or in containers, blueberries need full sun. If they’re on a patio or deck in a hot climate (i.e. not here in Ithaca) you should place them so they are shaded from late afternoon sun.
When preparing the soil, mix in a complete slow release fertilizer. Plant each high bush shrub 4 feet apart with 10 feet between rows to allow for mowing and equipment. Mulch the plants with sawdust, straw, woodchips or bark mulch.
Pests and diseases
Blueberries have very few pests and diseases. The greatest threats will likely be deer and birds. Deer must be fenced out, or a deer repellent can be used. GreenTree carries deer repellent spray, and some people hang pie tins or CDs nearby or play recorded predator calls to scare birds away from the ripe berries. Bird netting secured over the bushes is the best way to keep them out.
Blueberry maggots and more recently the non-native, spotted-winged drosophila (left) are two pests blueberry growers need to be concerned with. Both can be trapped to monitor and numbers of both can be reduced by picking ripe berries regularly and not letting them get over-ripe.
Blueberries grow well in containers, and you can grow them on your deck and patio. Here in Ithaca that means you may get to the berries before the deer!
Choose a variety that is suitable for your climate and which will not get too large:
- Northern Highbush ‘Top Hat’ grows best in cool climates (USDA zones 3-7)
- Southern Highbush ‘Sunshine Blue’ grows well in warm climates (USDA zones 5-10)
Establish your bare root or transplant in a 5-gallon container and transplant to a larger container after a couple of years. The roots are wide and shallow so containers should be chosen accordingly. Once the bush is established roots can be pruned every 3 or 4 years to maintain their size.
Soil for container planting
Just like growing in the ground, the pH of the potting soil you use will have to be acidic. Here at GreenTree we make it easy for you with our special blueberry soil. We use GreenTree Coco to ensure that our soil will retain water. Blueberries like to be damp, but not water-logged, so we blend in specially sized and aged pine bark components to ensure drainage. Once we’ve got the soil structure right we adjust our GreenTree Blueberry to a pH of 5 for ideal blueberry growing conditions. We make the GreenTree Blueberry mix on demand, so please contact us to place your order.
When growing in containers in cold areas, your blueberries will still die back in the winter. Remove any dead leaves and place the containers in a dry place like a garage or basement to overwinter. Move them back outside in the spring.
Use fertilizers that will gently increase soil acidity. We stock a North Country Organics fertilizer product called Pro-Holly 4-6-4, specially formulated for acid-loving plants like blueberries. Cottonseed meal or feather meal will gently acidify your soil and provide for the needs of your bush as it grows. Blueberries have tender roots which are easily burned by too much food. Use diluted nitrogen fertilizers, early in the season, never after flowering or new growth will be susceptible to winter injury.
Your bushes need to be well watered. GreenTree sells Raindrip irrigation to help with this. Pressure compensating drippers are an ideal solution. Mulch on the surface of the soil or container can help retain moisture. We have specially aged mulch that will help with moisture retention but will not compete with your bush for nutrients.