Grow Beautiful & Beneficial Blueberries!
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Q. Dear Mike: I'll be planting eight two-year old blueberry bushes in the Spring. I have clay soil, lots of sun and plan to put them in raised beds. Otherwise, I have no idea what to do. A dear friend will also be planting eight bushes, and we have a friendly wager to see who can produce the most bountiful crop. May the best gardener win!
- ---Pauline in Marlton, NJ
Sun is good. Although blueberries can take some shade, you get the most berries in full sun. And eight plants is very good! Even varieties touted as 'self-pollinating' don't produce nearly as well as plants with a lot of company. Clay soil, of course, is bad. But you're going to build a little peat bog for your plants anyway if you want to win that bet.
Blueberries need ridiculously acidic soil. Although most sources give a range of 4 to 5.5, they really don't like a pH higher than 5; and they will quickly join The Choir Invisible in soil with a normal pH. So excavate their planting area as deeply as your muscles allow, use a garden fork to break up the clay at the bottom and refill the hole with equal amounts of milled peat moss, compost and any native soil you have that doesn't look like clay. A researcher we quoted in an old OG story on blueberry growing specified a minimum of one five-gallon bucket of milled peat per plant. But don't fill the hole with just peat moss; you need the compost and soil in there to provide food and stability for the plants.
Then mulch the plants with an inch of peat moss, an inch of compost on top of that and then some well-shredded leaves. As always, don't let any mulch actually touch the plants. Like azaleas and rhododendrons, blueberries are shallow rooted and water hungry, and you'll need all members of that mulch combo to keep moisture in the soil and prevent competition from grass and weeds.
Then buy a pH meter and use it to test the soil around your blueberries. If a yearly mulching with naturally acidic materials like peat moss and shredded oak leaves can't keep the pH low enough, you'll have to turn to sulfur. It's natural and lowers pH well, but it takes a long time to become active in soil, so ideally you'd apply it now if you know you're going to need it. (Heck; ideally, you'd apply it a year in advance!) Three-quarters of a pound of sulfur should lower the pH of 100-square feet of sandy soil one point; it'll take a full pound in clay soils. And pay attention to the plants; their color will tell you if they're happy with the pH or not. Nice deep green leaves are the best sign of pH success.
Feed them yearly with a nice fresh mulch of compost in the Spring; on top of fresh peat moss, of course! (Spread out the old mulch so that it prevents weeds and grass further out.) As the season progresses and the plants flower and set fruit, you can water them every couple of weeks with compost tea, or give them a one-time boost with a gentle organic fruit fertilizer. No Miracle-Grow, Osmocote or other chemical crap!
And finally, forget the raised beds. I have my blueberries in flat ground. I prefer to save my raised beds for summer annuals, and it's easier to keep super-thirsty plants watered in flat ground.
Q. Mike: I have three terribly neglected blueberry bushes in an area we just cleared of saplings and excess blackberry bushes. These plants need a boost - what do you suggest?
- ---Valerie in Bennington, NH
Test the pH of their soil now. If it's close, a thick mulch of peat moss and compost should be enough. If it isn't, dust sulfur this winter. And they probably need a good pruning; do this late winter/early Spring, removing any dead, diseased, broken or very low hanging branches. If the plants have become crowded, open up the centers as well, just like a fruit tree. Your local county extension service will probably have some nice handouts on pruning for your specific area.
Q. Mike: I would like to grow blueberries, but am concerned about watering. It is my understanding that blueberries like acid soil, and we have very hard water and very little rainwater to collect during the summer. Any suggestions? Or is this just a no-go idea?
- ---Jess near Spokane, WA
Q. I only caught the tail end of a call on your show about using CDs to keep birds away. Robins always clean out my blueberries. What do I do with the CDs? Play them or hang them? Thanks.
- ---Lorraine, Dresher PA
Birds are notorious for devouring these delicious fruits; and although some people swear that hanging CDs nearby will deter them, I wouldn't bet my blueberry breakfast on it! I have found only two things to be effective.
One is bird netting; be sure to hang it on supports around the plants, not on the plants themselves, or the birds will just perch on it as they eat your berries. The other is a motion-activated sprinkler like "The Scarecrow" aimed at the plants. And, hey—with the way birds go after these berries, that sprinkler will make sure the plants don't dry out!
Note: As always, this is just the basics. You'll find lots more info on blueberries— including a discussion of the different types and varieties—at this fine site I recently discovered. Oh, and as promised, here's a link to our previous Question of the Week extolling the brainy benefits of eating blueberries.
And here's a nice little bit from Fine Gardening on the hard water problem.