How to Grow Blackberries

If someone plans to grow blackberries, there’s good news that these berries can be easily grown. The plant is pretty unfussy and if given full sun and well-drained soil enriched with garden compost, growers can even expect a plentiful harvest which they can pick every other day.

Blackberries are commonly grown across the United States and are eaten fresh or used in baked goodies or are preserved. Picking wild berries has a risk of getting pricked by the thorny vines while trying to obtain the tender fruit. However, fortunately, this risk can be eliminated by growing blackberries at home as now new thornless cultivars are available. Here are methods to grow and pick blackberries in one’s own backyard.

Published: April 20, 2020.

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Understanding How Blackberry Plants Grow

Blackberries bear fruits on canes from the plant’s part known as ‘crown’ which is right at ground level which is a meeting point of canes above the ground and roots below the ground. While raspberries spread and grow canes even from roots, blackberries produce canes only from the crown.

Brand new canes are bright green during the growing season and are known as “primocanes”. These won’t bear fruit until their second year. Once they become two-year old and start bearing fruits, they are known as “floricanes”. These now have a thin brown bark. After the second year, they die, never to fruit again. By late winter they are covered with a gray peeling bark that looks prominent. All these old, peeling canes should be cut back to the crown.

Types of Blackberries

Blackberries come in three types:

1. Thorny erect blackberries

2. Thornless erect blackberries

3. Thornless trailing blackberries

Erect blackberries are plants that grow straight, without any other support, whereas trailing blackberries have long flexible canes and should be given a support of a trellis.
Crown and roots of blackberry are perennial and survive for years, often for a decade or two. However, the plant above the soil is biennial, i.e. the canes live only for two years.

They grow vegetatively for a year, bear fruit the next year and then perish. However, new canes grow up every year in place of the dead ones. Therefore pruning is important in order to avoid a mess in the plant and for an abundant harvest.

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Recommended Varieties

There are some popular blackberry varieties. However, growers should ask about varieties that fit their growing zone.

- ‘Arapaho’, ‘Navaho’: Erect thornless

- ‘Cheyenne’, ‘Shawnee’, ‘Brazos’ and ‘Cherokee’: Erect thorny

- ‘Black Satin’: Semi-erect

- Olallie: Trailing

Planting of Blackberries

Ideal Time to Plant Blackberries

An ideal time to plant blackberries is early spring when canes are dormant. Even late fall can be the right time for planting. However, if the grower’s area is very cold, it should be delayed till early spring because some hybrid varieties may be killed due to low temperatures.

As mentioned earlier, blackberries are very easy to grow because they (including hybrids) are self-fruitful which means that the grower needs to plant only one cultivar; multiple plants are not required for getting many plants and fruits. In general, five to six plants can produce enough blackberries for a family of four.

Choosing and Preparing a Site

For the best blackberry yields, growers should choose a spot that receives full sun.

Soil should be fertile with good drainage. It should be enriched by adding organic content. If the site is elevated or if raised beds are prepared for the plants, it will not only have a good drainage, but also will protect flower buds from the damage caused by late spring frosts.

It’s advisable to conduct a soil test to know what soil amendments should be made so that the blackberries can get the right soil pH and nutrition. Blackberries prefer slightly acidic soil with pH between 5.6 and 6.2. If the soil is less acidic, lime should be added to increase the pH, whereas if it’s more acidic, garden sulfur or other products should be added to reduce acidity. Guidance can be acquired from one’s local country extension office.

Unless the soil is already perfect, one would want to add a 2” layer of composted cow manure and a 2” layer of an organic soil conditioner on top of the soil and work them to a depth of 8”-10”.

It’s best to make soil amendments before digging planting holes. If the plants are to be grown in containers, a commercial potting mix made for acid-loving plants can be used.

All weeds should be removed because they may compete with blackberry plants for water and nutrients.

Planting should be avoided in soils where previous crops included raspberries, strawberries, tomatoes, potatoes, peppers and eggplant. These crops may be a haven to soil pathogens, verticillium, nematodes and phytophthora that may affect the new plants.

Growers should also make sure they plant their blackberries far away from wild blackberries, because the wild plants may carry diseases that could weaken their own plants.

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How to Plant?

Many blackberry plants are sold as dormant ‘bare root’ plants i.e. dormant roots with all the soil removed. This is great for getting berries off to the perfect start. Or newer varieties are also sold in containers.

Plants of semi-erect cultivars should be spaced 5-6 feet apart. Plants of erect cultivars should be spaced 3 feet apart. Trailing varieties should be spaced 5 to 8 feet apart. Rows should be spaced around 8 feet apart. Proper spacing allows good air circulation and prevention of the spread of diseases.

A planting hole wide enough to accommodate the roots without cramping them should be dug and the blackberry shrub should be placed in it, positioning it in such a way that the crown, where the stem and roots meet, comes at the level of the surrounding soil. After filling the hole around three-quarters with soil, filling should be stopped and a gallon or two of water should be poured in the hole with which the soil can settle and any air pockets will be removed. After backfilling, the soil should be tamped down with hands and once again should be watered well.

Plants should be grown shallowly i.e. around an inch deeper than they were grown in the nursery. Since roots of blackberries are shallow, a 3-4 inch layer of organic mulch, like pine needles or compost should be added to protect them.

Trailing Blackberries

As mentioned earlier, trailing blackberries should be supported with a trellis or other types of support.

Growers can build a trellis with minimal material. They have to sink two 8’ pressure-treated 4x4 posts 3’ deep in the ground. In the case of sandy soil, a quick-setting mortar mix can be added to anchor the posts. In the case of clay soil, the soil can simply be tamped down to hold the posts in place. The posts should be set anywhere between 10’ and 20’ apart. On each post, two marks should be made – one at 2 ½” off the ground and the other at 4 ½” off the ground. A 9-gauge coated wire should then be attached at those marks to the post with staples.

Blackberries don’t have to be trained to the trellis during the first growing season. Canes should be tied to the trellis at the start of the second year.
One method is to tie primocanes loosely to the wire while they develop. This should ideally be started before buds swell in early spring. When the canes become tall enough to reach the top wire, they should be tied horizontally along the wire.

The other method which many gardeners use is to train only the floricanes to the trellis and allow the primocanes to sprawl on the ground.

Growing Blackberries in Containers

If the grower doesn’t have a proper garden or yard, they don’t have to be discouraged. Blackberries can be planted even in containers. For this, a compact cultivar such as Baby Cakes should be chosen. It doesn’t need pruning. However containers should be large enough to hold at least 5 gallons of soil so as to prevent drying out. As mentioned earlier, a commercial potting mix made for acid-loving plants can be used for growing blackberries in containers.

Growing Blackberries from Seeds

As mentioned earlier, blackberries are sold as potted plants or dormant roots. If the grower has the patience to grow the berries from seeds, they should plant the seeds in the ground during the fall. They need a period of cold dormancy to germinate.

Propagating Blackberries

It’s easy to propagate blackberries. They can be propagated by cuttings (stem and root), suckers and tip layering. Irrespective of the method used, the new plant will typically look similar to the parent variety, particularly when it comes to thorns (i.e. a thorned variety will have thorns and a thornless variety won’t have thorns).

Propagation through Cuttings

Both leafy stem cuttings and root cuttings can be used for propagation. But leafy stem cuttings are the best if one wants to propagate a lot of plants. This is often done while the cane is still strong and succulent. Around 10-15 cm (4-6 inches) of cane stems should be used. They should be placed in a sand mix/moist peat sticking them in a few inches deep. The application of root hormone can be done but is not necessary. Roots should start developing within 3-4 weeks.

If root cuttings are used for propagation, they should be anywhere from 7.5 to 15 cm (3 to 6 inches) long and should be taken in fall when they are dormant. They generally need around a 3-week period of cold storage, especially if the roots are larger. Straight cuts should be made closest to the crown and an angled cut should be made further away.

Once the cuttings are prepared, they should be bunched together and cold stored at around 4°C (40°F) in the refrigerator or outdoors in a dry area. After that, just like the stem cuttings, they should be placed in a sand mix or moist peat, around 5-7.5 cm (2-3 inches) apart with their straight ends sticking a few inches into the soil.

If cuttings are small-rooted, only small 5cm (2-inch) sections are used. They are to be placed horizontally over the sand mix/moist peat and lightly covered. Then they are covered in plastic till new shoots emerge. Once roots are formed, all cuttings can be planted in the yard.

Propagation through Suckers

One of the easiest ways to root blackberry plants is through suckers. Suckers can be taken from the parent plant and then replanted in the desired spot.

Propagation through Tip Layering

The method of tip layering works well for trailing cultivars and when just a few plants are required. It should be done in late summer or early fall. Growers should just bend young shoots over to the ground and cover them with soil up to a few inches. This should be then left that way all through the fall and winter. There should be significant root formation by the spring and then the plant can be cut from the parent plant and replanted elsewhere.

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Taking Care of Blackberries

Mulching

Mulching is essential all through the season to preserve moisture and smother weeds. Growers should make sure that a thick layer of mulch always surrounds the plants.

Watering

An ample amount of moisture is required by blackberries, particularly while growing and ripening. Growers should also make sure that the plants receive an inch of water every week and more if temperatures are hot. If blackberries are planted in raised beds, drip irrigation is a must. Drip irrigation is overall good for blackberry because it supplies water directly to the roots keeping leaves dry and reducing the possibilities of diseases.

Fertilizers

Fertilizing should be done in early spring with an all-purpose fertilizer in which all the N-P-K numbers (Nitrogen-Phosphorus-Potassium) are the same like 10-10-10. Second feeding should be given after six weeks, so as to keep them well-fed.

Attention should be given to the foliage. Leaves should look bright green. If they are looking yellow or pale green, it means that they are experiencing nitrogen deficiency.

Protection from Insects

Growers should always watch for insect pests that can spoil the hard-earned yield. A pesticide that can control a broad spectrum of insects should be used.

Pruning

Although the process of pruning blackberry plants may seem intricate, the grower should not worry, as the underlying idea is just to remove the old canes that already bore fruits and allow the new ones to replace them.

Pruning Erect Blackberries

Stiff, shorter canes are produced on erect blackberries. These come from the crown and from root suckering (usually creating a hedgerow).

Summer pruning is beneficial for erect blackberries. The top one to two inches of new primocanes should be removed when they reach a height of four feet. This enables the canes to branch and next year’s yields increase. Many pruning sessions will be needed by the plants to tip each cane as it becomes four feet tall. Primocanes (suckers) growing outside the hedgerow should be removed regularly.

The dead floricanes (old fruiting canes) should be removed from the hedgerow in the winter. The lateral branches too should be shortened to around 1 ½ to 2 ½ feet.

Pruning of Primocane-Fruiting Erect Blackberries

In the late winter, all canes should be cut off just above the ground for the best yield. When the primocanes will reach the height of 3 ½ feet in the summer, the top 6 inches should be removed. This way, the primocanes will branch, giving larger yields in the fall.

Pruning of Semi-Erect Blackberries

Semi-erect blackberries are easier to work with on a Double T Trellis. This can be created by installing a three-foot cross arm around two feet below the top line. High-tensile wire should be strung down the rows to connect the cross arms.

Pruning of semi-erect blackberries should be done in the summer. When the primocanes reach the height of 5 feet, the top two inches should be removed to encourage branching. Many pruning sessions should be done as canes reach the correct height. The old fruiting canes (dead floricanes) should be removed in the winter.

The new floricanes (primocanes) should be spread out along the trellis. As such canes don’t need to be shortened. However, if they are hard to train, they can be shortened.

Pruning Trailing Blackberries

After the period of fruit harvest, floricanes (the old fruiting canes) are removed. However, the removal of the floricanes should be delayed (unless some disease has grabbed the plants to a high extent) until they die considerably. Dying canes transfer nutrients back into the crown and roots.

After removal of old fruiting canes, the primocanes should be trained up on the wires. Only one or two canes should be worked with at a time in a spiral around the trellis wires. There may be some overlapping from the nearby plants. Primocanes don’t need to be pruned.

If the grower’s area receives low winter temperature, the primocanes should be left on the ground for the winter so that they could be mulched for winter protection. After the threat of extreme cold passes, in the spring, the old primocanes (now considered floricanes) should be trained up on the wires. Growers should avoid working with the canes if the weather is cold, as they are likely to break.

Pruning Container-grown Blackberries

If the plant is grown in a container or is a compact plant, pruning is quite simple. Sharp, bypass pruning shears or long-handled loppers should be used.

Note: If the blackberry plants are thorny, growers should wear thick protective gloves, heavy jacket and protective eyewear while pruning the plants to protect their hands, arms and eyes respectively.

Pests and Diseases

Blackberries are vulnerable to stem blight, anthracnose and crown gall. To prevent diseases, disease-free plants should be purchased from reputable nurseries and they should be planted far away from the wild brambles.

Insects commonly occurring on blackberries include raspberry crown borers and stink bugs.

Insects are less attracted to healthy vigorous plants.

How to Harvest

Only berries that are totally black should be picked. Mature berries are those that are deep black, plump yet firm, and yank freely from the plants without a tug. It should be remembered that berries don’t ripen once they are picked.

Once berries begin to ripen, they should be picked frequently, i.e. every couple of days.

While picking, the central plug should be kept within the fruit (unlike raspberries).

Harvesting should be done during the cooler parts of the day.

Once picked, the berries should be kept in the shade and refrigerated as soon as possible.

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Photo by Pexels

How to Store

It should be remembered that blackberries are extremely perishable and won’t last for many days after harvest, even if they are refrigerated.

Even though fresh fruit is anytime best, blackberries can be preserved by canning, freezing or preserving. Methods used for freezing blueberries can be used for blackberries too.

Blackberries are highly nutritious and delicious fruits that offer a variety of options for growing and consuming. So, why not to take the benefit and grow them at home?