Blueberry
Vaccinium corymbosum
Everything depends on soil pH. Get that wrong and nothing else you do matters.
pH 4.5 to 5.5, and nothing else will do
Most soil in this valley runs neutral to alkaline. Above about pH 5.5 blueberries cannot take up iron, and you get yellow leaves with green veins, poor growth and no crop, no matter how well you water and feed. Test before planting. Lower pH with elemental sulfur applied six to twelve months ahead - it works slowly through soil bacteria - and re-test annually, because soil drifts back upward. This is our acid-lovers amendment's reason for existing.
Consider a dedicated bed or container
If your soil is strongly alkaline, fighting it forever is a losing game. A raised bed filled with a peat-and-pine-bark mix, or large containers of ericaceous compost, is far more reliable and much less work over time.
Shallow, fibrous roots
Blueberry roots are fine, shallow and have no root hairs, which means they cannot forage. They need constant even moisture, a permanent three to four inch mulch of pine bark, pine needles or sawdust, and they will not compete with grass - keep a clear mulched circle around each bush.
Two varieties for better fruit
Northern highbush varieties are technically self-fertile, but cross-pollination between two varieties that bloom together gives noticeably bigger berries, better set and earlier ripening. Plant at least two, and choose an early, mid and late variety to spread the harvest over six weeks or more.
Feeding
Use ammonium sulfate or a fertiliser formulated for acid-loving plants; nitrate-based fertilisers can damage them. Feed lightly in early spring and again after bloom. Never lime, and avoid manure, which is alkaline and salty.
Pinch flowers for two years
Remove blossoms in the first year or two after planting so the bush builds structure and roots. As with strawberries and asparagus, the early restraint pays back many times.
Pruning
From year three or four, prune in late winter. Remove dead, weak and twiggy wood, and take out one or two of the oldest canes (over six years, thick and grey) each year at the base to force strong new canes. Fruit is best on two to four year old wood. An unpruned bush becomes a mass of twiggy growth with small berries.
Birds are the main pest
They will take the entire crop. Netting over a frame is the only reliable answer - drape netting directly on the bush and birds simply perch on it and feed through. Spotted wing drosophila is an increasing problem in late varieties.
Harvest and storage
A blueberry is not ripe when it turns blue - wait another three to seven days until it detaches at the lightest touch and the scar end has coloured fully. This is the commonest mistake and the difference is large. Ripe berries keep one to two weeks refrigerated and freeze perfectly on a tray, unwashed, then bagged.
- Hardiness
- Zone 4-8
- First fruit
- Year 3
- Spacing
- 4-6 ft
- Row spacing
- 8-10 ft
- Sun
- Full
- pH
- 4.5-5.5
- Pollination
- Two varieties better
- Life
- 20-40 yrs