Tips on growing blueberries

There is already a lot of information out there about growing blueberries so we will stick to what seems to work in this part of Rhode Island. (We no longer sell blueberry plants, but they are sometimes available at Lowes, Home Depot or Morris Farm: 2779 Warwick Avenue, phone 401 738-1036.)

Location and soil: Blueberries do best in full sun; they will grow and produce in half-day sun, but the crop will be reduced. They require soil that is acid--pH of 4.5 to 5 is ideal. Most Rhode Island soils are naturally acid. However, if you are planting in a lawn that has been limed to raise the pH, you will need to take measures to lower it. You can dig a large hole and mix in peat moss, which is naturally acid. (Peat moss is an ideal medium for blueberries; use at least one cubic foot per plant, whether or not you need to lower the pH.) You can also, or instead, mix sulfur into the planting bed to lower the pH. The soil should be a little sandy, for good drainage (we have some poorly drained spots at Rocky Point Farm, and you can see that the plants in those spots don't do well). There should be plenty of organic material in the soil. Compost is good, and specialists at the University of Rhode Island determined that sawdust, both mixed into the soil and as a mulch, is very good.

blueberries in winter

Planting: Late fall is best for planting, but early spring is also OK. If you buy your plants in pots in the summer, keep them well watered until its time to plant in October. Holding potted plants over winter is not recommended. The bed should be weed free; blueberries cannot stand competition from grass or weeds. Space the plants 4 feet apart. Dig a hole to accommodate the plant, remove it from the pot, if roots are solidly packed tease them out carefully and spread them out from the stem, so they'll grow outward. Place the plant in the hole, bring soil around it and pack down. Plant at the same level it was in the pot, or an inch aboveground, as blueberry roots grow close to the surface and can be smothered if planted too deeply. Water thoroughly and keep soil moist until winter. Do not fertilize at this time. Mulch deeply with whatever you have at hand--wood chips, chopped leaves, sawdust, or whatever. If you use sawdust or peat moss, which can dry and shed rain, form the mulch into a bowl so rain will drain toward the plant. If you have rabbits, the plant will need some protection; rabbits love to munch on blueberry buds and branches during the winter.


Care: The first year, make sure the soil around the plant is always moist. Prune off the fruit buds; you want your little bush to grow big and strong, not to try and produce berries! (Prune off the fruit buds the second year also.) A heavy mulch is very helpful. Fertilize sparingly--a tablespoon of Miracid in May, spread thinly at least six inches away from the stem and watered in, is sufficient, unless you use a woody mulch such as wood chips or sawdust, which will temporarily tie up nitrogen in the soil; in that case, another tablespoon in June and another in July will help. The second and third years, a little more Miracid, or another fertilizer high in nitrogen, is called for. An organic fertilizer would be good if it is high in nitrogen.

Beginning in the third year, prune during the dormant season to remove any twiggy growth near the ground and any anemic looking stems.

After the third year, pruning should be done annually, bearing in mind that fruit is produced on the previous season's wood. You want to encourage new growth, and also to have larger, if fewer, berries. Remove dead or sickly branches, branches low to the ground, and older, less vigorous stems.

The bushes will reach maturity in the eighth to tenth year, by which point you should be pruning annually. If your bushes grow multiple canes from the ground, remove one or more of the oldest ones each year, and keep the number of canes, young and old, to ten or so. If your bushes take a tree-like form, prune out older branches to encourage new growth.

Blueray blueberry bush before pruning
Mature Blue Ray before pruning
blueray blueberry bush after pruning
Mature Blue Ray after pruning

Your older bushes should be under a heavy mulch, and will require significant amounts of nitrogen each year, applied in May and June. You can calculate the amount of fertilizer needed by looking up the percentage of nitrogen in your fertilizer (10-5-5 is 10% nitrogen) and calculating how much is needed to supply 0.8 to 1.6 ounces of nitrogen to each mature plant, depending on how heavily they are mulched, and whether it is a woody mulch. Split that amount into two or more applications.

By the fourth year you should have begun getting berries, but you may have to fight the birds for them. We have found the only effective bird repellent is netting, preferably hung from wires above the plants and fastened to the ground.

Varieties: You will want to plant at least two varieties, to assure cross pollination. There are dozens of varieties commercially available. See the Varieties tab for information about our varieties.