How to Plant Blueberries: Bed Preparation, Spacing and Depth

Plant while the bush is dormant

Bare-root plants go in during dormancy, from late autumn through to the end of winter, whenever the ground is not frozen or waterlogged. Autumn planting in a mild region gives the roots months to settle before the plant has to support leaves. Where winters are severe, wait until late winter so a young plant is not sitting frozen and unestablished.

Container-grown plants can go in almost any time the ground is workable, but the same logic applies: planted in dormancy they establish without the plant having to run leaves and roots at once. Planting in high summer means daily watering for weeks and a bush that spends its first season merely surviving.

Build the bed before you dig the hole

The mistake that costs most is digging a normal hole, dropping the plant in, and backfilling with the soil that came out. Blueberry roots occupy a shallow pancake roughly as wide as the bush and only 12 to 18 inches (30 to 45 cm) deep, and almost all of that sits in the top foot. So the job is to improve a wide, shallow area rather than a deep hole.

Work a barrowload of acidic organic matter into an area three feet (90 cm) across for each plant, forking it into the top foot rather than burying it deep. Composted pine bark, coir, or an ericaceous planting mix all work. If your soil is heavy clay, raise the whole bed eight to twelve inches (20 to 30 cm) instead of digging down, because roots that sit in winter wet rot.

1. Test and correct the pH months ahead Sulfur takes three to six months to work. Testing at planting time and applying sulfur into the hole is too late for the first season, so measure the autumn before you intend to plant.
2. Improve wide, not deep Fork organic matter through a three foot (90 cm) circle to the depth of a spade. A rich pocket in a narrow hole makes roots circle inside it instead of spreading.
3. Raise it if drainage is doubtful Where water stands after rain, mound the bed eight to twelve inches (20 to 30 cm) above the surrounding level. Blueberries want constant moisture and hate standing water, and a raised bed gives you both.
4. Leave the fertilizer out Do not put granular fertilizer in the planting hole. The fine roots burn easily, and a plant with damaged roots at planting takes a full season to recover.

Fresh sawdust and wood chips take nitrogen out of the soil as they decompose. Use them as a surface mulch, where that matters far less, rather than forking them in.

Getting the plant in the ground

A container blueberry usually arrives with the rootball wound tightly and often bone dry in the center, because the peat-based mix sheds water once it has dried. Both problems have to be dealt with at planting or the roots never leave the ball they came in.

1. Soak the rootball first Stand the pot in a bucket of water for half an hour until bubbles stop rising. A dry peat rootball planted as it is will stay dry even in a well watered bed, and the plant dies with wet soil all around it.
2. Tease the roots out Pull the outer roots loose with your fingers, and slice down the sides of a badly bound ball in three or four places with a knife. It looks brutal and it is the difference between roots that spread and roots that circle.
3. Plant at the same depth or slightly proud Set the top of the rootball level with the soil surface, or half an inch (1 cm) above it on heavy ground. Burying the crown of a blueberry invites rot at the base of the stems.
4. Backfill with the improved mix Firm the soil in with your hands rather than treading it. Blueberry roots are fine enough that heavy compaction around them slows establishment noticeably.
5. Water in thoroughly Two full watering cans per plant on the day, applied slowly so it soaks rather than runs off. This settles the soil against the roots more effectively than any amount of firming.

Spacing, mulch and the first year

Space highbush plants four to five feet (1.2 to 1.5 m) apart, and rabbiteye six to eight feet (1.8 to 2.4 m), because a rabbiteye reaches a size most people underestimate. Planting closer for a quick hedge gives you crowded, unproductive bushes within five years and makes picking miserable.

Mulch three inches (8 cm) deep over the whole root area as soon as you have planted, keeping it an inch or two clear of the stems themselves. Pine bark, pine needles or composted sawdust are the standard choices. This is not optional decoration: the shallow root system dries and overheats without it, and mulch is the single biggest factor in how well a young blueberry establishes.

Strip the flowers off in the first year, and on a weak plant the second year too. It feels wasteful and it builds the root system and framework that carry every crop after that.

You need two different plants, not one

Blueberry flowers carry both male and female parts and will set some fruit on their own pollen, which is where the widespread claim that they are self-fertile comes from. It is technically true and practically misleading. A lone bush gives a light crop of small berries that ripen late and unevenly.

Plant a second, genetically different bush of the same type within about 20 feet (6 m) and the same plant sets more berries, each one larger, ripening several days earlier. The mechanism is direct: pollen from a different plant fertilizes more of the ovules in each flower, more seeds form, and berry size follows seed number. For rabbiteye types this is not an improvement but a requirement, because most set almost nothing on their own pollen.

1. Two different plants, not two of the same Two bushes propagated from one parent are genetically identical and count as a single plant for pollination. The partner has to be a genuinely different selection, which is why nurseries sell them in pairs.
2. Match the type to its partner Cross a northern highbush with another northern highbush, and a rabbiteye with another rabbiteye. The two groups flower at different times and belong to different species, so they pollinate each other poorly or not at all.
3. Match the flowering window Both plants have to be open at the same time. Pair an early with a mid season, or a mid with a late, rather than an early with a late that barely overlap.
4. Keep them close together Bees work a short radius. Within 10 feet (3 m) is ideal and 20 feet (6 m) is workable, while planting them at opposite ends of the garden achieves very little.
5. In containers, stand the pots together Two pots side by side pollinate as well as two bushes in a bed. Spacing them around a patio for the look of it undoes the whole benefit.

Three plants of three different selections beat two, because they widen the window in which some pollen is always available. It is the cheapest improvement you can make to a blueberry crop.

Planting into containers

A container is the right answer on alkaline soil and it works well, provided the pot is big enough. Start a young plant in something around 12 inches (30 cm) across and move it up every couple of years until it reaches an 18 to 24 inch (45 to 60 cm) final pot. Potting a small plant straight into a huge container leaves a mass of wet compost the roots cannot reach, which sours.

Use an acidic potting mix, ideally with 20 per cent composted bark stirred through for structure, and mulch the surface exactly as you would in the ground. Refresh the top third of the compost each spring, and every three or four years lift the plant out, trim the outer roots and repot into fresh mix.

Note the planting date, the type, and where each plant sits in the bed. Four years on, when one bush crops heavily and its neighbor does not, that record is what lets you work out why.