Soil pH comes first
Oregon State University's home garden guide describes blueberries as acid-loving plants, like rhododendrons, adapted to soils of pH 4.5–5.5. Most vegetable beds are kept at 6–7, so the first job is a soil test. Test kits and laboratory tests are compared in the soil pH guide.
- To lower the pH, Oregon State uses elemental sulfur, dug in well before planting. The dose depends on how far the pH has to fall and on the soil. For a clay loam starting at pH 5.7–6.5, it gives roughly 100–245 g/m². For sandy soil it gives about 50–145 g/m². The soil pH calculator works out a dose for your soil and target, split into safe applications.
- Once plants are in, Oregon State tops up with no more than about 85 g of sulfur per plant, in early autumn, if the pH creeps back up.
- Chalky or limestone soils can't realistically be acidified. The free lime neutralises the sulfur. Grow in pots or raised beds of acid mix instead.
- Keep alkaline materials away. Don't use lime or dolomite, and avoid mushroom compost. Penn State measures most spent mushroom compost at pH 6–8, and it can be salty.
Oregon State also digs in 5–10 cm of aged bark or sawdust across the planting area. After planting it mulches 5–8 cm deep, building up to 10–15 cm over the next five or six years. Organic matter and mulch suit the shallow, fibrous roots.
Northern highbush, southern highbush or rabbiteye
Berries Australia, the industry body, describes three types:
| Type | Chill hours | Frost | Leaves | Best in |
|---|---|---|---|---|
| Northern highbush | 750–1,000 | Very hardy | Deciduous | Cooler areas with frost; long-lived, up to 30 years |
| Southern highbush | 250–600 | Don't survive frosts | Semi or fully evergreen | Warmer areas; bred for heat and low chill; about 10 years |
| Rabbiteye | 450–600 | Tolerates a range of conditions | Semi or fully evergreen | Warmer areas; late season, firmer berries; not for cool districts |
Chill hours measure the winter cold a bush needs to satisfy its dormancy. Choose a type whose needs your winters can meet, and match it to your climate, as in the planting calendar zones: northern highbush where winters are cold, southern highbush or rabbiteye where they are mild.
All three crop better with a second variety of the same type nearby. Oregon State says most varieties set fruit on their own, but cross-pollination gives bigger berries and more of them.
Blueberries in pots
A pot is the easy answer on alkaline or clay soil, because you control the mix. Oregon State's guidance:
- Size: larger types such as northern highbush need a big container, about half a wine barrel or 57–76 litres. Smaller, compact varieties manage in less.
- Mix: mostly well-aged fine bark (50–80 %), with 10–40 % peat and about 10 % perlite or pumice. In shops, look for an acid mix such as those sold for azaleas and camellias.
- Water: pots dry out fast in summer. A dripper on a timer takes care of hot weeks.
The potting mix calculator works out how many bags fill your pots.
Planting and the first two years
- When: Oregon State plants in autumn or spring. In the southern hemisphere that is roughly March to May or September to November.
- Spacing: about 90 cm apart for northern highbush and 1.5 m for rabbiteye, with 2.4 m or more between rows.
- Prune at planting: Oregon State removes about 30–40 % of the new bush and picks off the flower buds in the first season. That puts the plant's energy into roots and shoots.
- First fruit: one or two years after planting, rising to a full crop over several years. A mature northern highbush gives about 4–7 kg a year in Oregon State's figures.
Feeding, water and pruning
- Fertiliser: blueberries use nitrogen in the ammonium form. Oregon State recommends ammonium sulfate (sulphate of ammonia, 21 % N) or urea. It warns that many all-purpose garden fertilisers supply mainly nitrate, which doesn't suit them. It splits the year's feed into three doses from mid-spring to early summer. The fertiliser calculator has sulphate of ammonia built in.
- Water: the roots are shallow, so water little and often enough to keep the top 15–30 cm moist. In dry summer weather Oregon State gives established plants about 40–75 mm a week, and calls drip ideal. See the watering calculator for run times.
- Pruning: prune every winter while the bush is dormant, before the buds burst. Keep it open, like a vase, and cut out old canes that no longer crop and thin, twiggy wood.
Questions
What soil pH do blueberries need?
4.5–5.5, well below the 6–7 most vegetables like. Test first, then lower the pH with elemental sulfur several months before planting. On chalky or limestone soil, grow them in pots of acid mix instead.
Can I grow blueberries in a pot?
Yes, and on alkaline soil it is the better choice. Use a large pot, about half a wine barrel (57–76 L) for a full-size bush, and an acid mix based on aged bark. Water often in summer.
Do I need two blueberry bushes?
Not strictly, as most varieties set some fruit alone. But a second variety of the same type flowering nearby gives bigger berries and more of them, which is why both Oregon State and Berries Australia recommend it.
Which blueberry grows in a warm climate?
Southern highbush, bred for heat and low winter chill (250–600 hours), or rabbiteye (450–600 hours). Northern highbush needs 750–1,000 chill hours and belongs in cooler, frosty areas.
Sources
- Oregon State University Extension, Growing blueberries in your home garden (EC 1304, revised May 2025). Covers pH, sulfur, bark and mulch, planting and spacing, pruning, ammonium fertilisers, watering, pollination, first harvest and containers.
- Berries Australia, Blueberry varieties. Covers chill hours, frost tolerance, foliage, lifespan, suitable areas and cross-pollination.
- Penn State Extension, Spent mushroom substrate as a soil amendment. Covers the pH and salts of mushroom compost.
- Sulfur doses converted from pounds per 100 square feet (1 lb/100 ft² ≈ 49 g/m²). Calcareous soils: the sources in the GardenMaths soil pH guide.
Last reviewed 24 September 2026 · Report an error