How to Grow Blackberries
Blackberry is great plant for any home gardener – it provides so much and require very little. As a fruit to grow, blackberry is not demanding plant and grows well in temperate zone.
If you decide to grow blackberries, it is very important to learn few things:
- how to select and prepare the soil for planting,
- how to select blackberry varieties that suit your soil, position and needs,
- how to maintain crops in order to achieve better yields and high quality of the fruits.
Blackberry is a perennial shrub of the family Rosaceae. It is possible to grow blackberries in both warm and cold regions - some varieties tolerate warmer, even tropical conditions.
Blackberry bush consists of relatively long shoots that grow from the roots and without support, they usually bend toward the ground. With enough moisture in the soil, branches that come in contact with the soil start to root – this is just one of the many ways blackberries can be propagated in backyard garden.
The leaves consist of 3 to 7 serrated elliptical small leaves, light to dark green in color. Blackberry flowers are small to medium-large, white, sometimes with light pink shades. Blackberry blooms from May onwards. Fruits are drupes aggregate with different forms and sizes - oval, round or elongated. The color of ripe blackberry is commonly gloss black.
Blackberry Types and Varieties
Blackberry shrubs can be divided into two basic types:
Erect blackberries - this type of blackberry shrubs have strong shoots that hold themselves upright – these blackberries require no additional support. These varieties are usually more resistant to low temperatures. Most common varieties are: Cherokee, Cheyenne, Shawnee etc.
Trailing blackberry - to grow vertically, this type of blackberries require some kind of support. Most common varieties are: Thornless, Black Satin, Boysenberry, Logan, Marion, Thornless Evergreen, Young, Waldo etc.
Semi-erect types – these blackberries have strong shoots, but they still require support to grow upright.
In addition to these basic divisions, blackberry cultivars also differ according to:
- if shrubs have thorns or not,
- if shrubs are deciduous or evergreen.
Most varieties can be purchased in both versions: with thorns or thornless. For growing blackberries in backyard garden, thornless varieties are highly recommended. On the other hand, when compared to the varieties with thorns, thornless varieties are somewhat susceptible to bad weather conditions – during both winter and summer.
Soil Selection for Growing Blackberries
Blackberry thrives in almost any soil that is commonly found in most backyards and small gardens. However, for growing blackberries one should avoid warm sandy soils, as well as cold, heavy and overly moist soils. The most suitable growing soils for blackberries are sandy loam, moderately moist soils of loess and similar soils. The best yields and best fruits are achieved on well-drained terrains with some peat or humus. Humus content should be around 2-4%, while the soil should be slightly acidic, with a pH being between 5.5 and 6.5.
What positions should be selected for growing blackberries?
Blackberries prefer warm and sunny positions. They can grow and bear fruits on partly shaded positions, but this can affect the quality of the fruits. Also, warm and dry winds could threaten blackberry plants, so it will dry out the soil and prevent proper flowering. Therefore, best positions for growing blackberries are:
- protected from the wind,
- well aerated and well-drained soils with pH 5.5 – 6.5,
- positions with plenty of sunlight.
If there are no dangers from the strong winds, the usual direction for planting blackberries is in the direction north – south. With enough distance between the rows (depending on the planned height of grown plants), this direction provide optimum amount of sunlight for every plant.
Choosing the most suitable position for growing blackberries depends on the local climate.
Blackberries prefer moderate conditions, although there are varieties that can thrive in warmer, almost tropical conditions. Therefore, the general rule is that in warmer areas at lower altitudes (200-300 m) one should avoid warmer southern locations – gentle slope toward east or west, or even north is preferred. For north – south slopes, varieties that prefer warmer conditions should be chosen. If you plan on growing only several plants in your home garden, choose position according to your local climate – in warmer areas, plant blackberries on partly shaded locations and in colder areas, choose sunny positions. Even better, plant them in suitable, larger, flower pots and test your plants – when you find the best position for plants you have, keep them there permanently. Note that blackberries can live up to or even more than 15 years!
In colder areas and at higher altitudes (up to 700 m) it is good practice to avoid northern positions. Choose terrain with gentle slope to the south, in order to protect blackberries from excessive cold and frost.
Although growing blackberries is possible in both colder and warmer areas, most varieties still don't tolerate extreme heat. The long, hot and dry summers are not especially suitable for growing blackberries – there is increased risk of soil drying out, premature fruit ripening and even plants themselves can be in danger.
During winter, blackberries are very resistant to frost, but during the harsher winter days, cold could threaten shallow root system, especially if the soil is too wet (hence the importance of soil with good drainage). In such conditions, some winter cover is required in order to protect the plants and especially root system.
Fertilization and Soil Maintenance
Blackberries don't require especially fertile soil – however, they will bear plenty of fruits when grown in the moderately rich, well drained soils. Fertilization should be carried out twice a year - in early spring (in March or April) and in autumn after the harvest (the best early October).
For spring fertilization, use mineral fertilizer rich in nitrogen (for example 20:10:10), but also add some humus and/or compost. If you have only several blackberry plants, using fertilizer optimized for berries with gradual release of nutrients is highly recommended. This is not the cheapest option, but on small scale, why not?
In the autumn, it is recommended to use manure, about 2-3 kg per square meter. If the soil is fertile, this process is repeated only every two or three years.
When manure is used, one should avoid the use of nitrogen fertilizers and limit the application of phosphorus and potassium fertilizers. If you do not use manure in the autumn, use NPK fertilizer – with the nutrient ratio of 10:12:26 or 15:15:15 - depending on the quality of the soil. After the fertilization, plow the soil some 10 cm (4 inches) in depth.
Support System for Growing Blackberries
Support system for semi-erect and trailing varieties must be set before or immediately after planting blackberries. For this purpose, use poles and galvanized wire - the shoots are loosely tied to the wires during their growth. The columns can be made out of different materials, like concrete, wood, metal or plastic. The main pillars are buried 0.5 to 0.7 m deep and are anchored there – usually with concrete. Similarly, columns are buried up to the 0.5m and anchored usually with some concrete – if you can, make support system in the autumn and plant the blackberries later.
Height of columns and number of wires vary, depending on the type of support system (single- wire support system, two-wire support system etc.), planted blackberries, wind conditions etc.
If you plan on growing blackberries in your garden, the most simplest way is to use 2.5 – 3 m (8-10 feet) poles (remember that 0.5 – 0.7m of them is buried in the ground) placed around 3 m (10 feet) apart, with two strong plants between each pole. Place first wire some 0.6 – 0.9 m (2-3 feet) above ground and then single wire every 0.3 – 0.5 m (1 – 1.5 feet). This way, shoots have solid support that protect them and hold firmly even during strong winds.
Of course, if you are growing erect blackberries, you don't need support system – great for small gardens and growing them in flower pots on permanent and semi-permanent positions.
Blackberry Plants - Planting
When buying blackberry plants, select those that have been tested for the presence of diseases and pests. Growing healthy plants from the beginning is very important, even when growing such plants like blackberries.
If you are planning on growing wild blackberries, before planting them in your garden, be sure to treat them in order to avoid any danger of diseases and pests.
Blackberries are planted in late autumn or winter, until the beginning of April. Before planting, be sure to add some humus to the soil - it will naturally regulate soil moisture and pH factor. Also, if needed, add some sand (but not much! - blackberries don't like sandy soils, but sand in small quantities actually can improve soil characteristics) and/or peat. On really heavy soils, one should add some peat, compost, humus and even some gravel up to 50cm deep (20 inches) in order to increase water drainage.
During the autumn, or at least a month before planting blackberries, plow the soil to a depth of 30 - 40 cm (12 – 16 cm). The spacing between rows and between plants in rows will depend on the chosen varieties and the support system. Spacing between plants for erect types of blackberries is around 60 - 120 cm (2-4 feet) and for trailing blackberries around 120 - 240 cm (4-8 feet).
In home gardens, distance between blackberry shrubs should be 1 – 1.5 m (3 – 5 feet) and this is the best along the fence. If you grow them in the flower pots, use larger pots (at least 60cm (2 feet) in diameter) and plant at most 2-3 plants per pot - in that case, be sure to water them regularly.
Watering of the Blackberry Plants
For proper growth, blackberries require moderate soil moisture. Water is very important in the development of annual shoots, but also for the growth of fruits. During the summer months, blackberries need about 30 mm (1.2 inches) of water every 7-10 days – that is around 20-30 liters of water per plant when grown in the garden soil every week. In the case of drip irrigation systems, this amount is slightly lower.
Pruning of Blackberry Plants
The first pruning of the blackberries is done immediately after planting. Remove anything that doesn't look healthy.
Plants that bear fruits are usually about 2 m high and should be shortened to 30 - 50 cm (1-2 feet) and smaller varieties up to 20 cm (8 inches). This will strengthen the roots and buds from which shoots will grow.
For better lighting and higher quality of the fruits, blackberry shrubs should be carefully thinned. Usually, one should leave 5-6 strong shoots (or 8-12 in stronger varieties) and the others are removed. Damaged or ill shoots should be cut to the ground. Two year old shoots that had fruits are also removed. At the end of the winter, it is good practice to shorten lateral twigs on one year old branches to the length of some 30-40 cm (12-16 inches). This way, the fruits next year will be bigger and better.
The blackberry fruit is very sensitive and susceptible to rapid deterioration. If blackberries are harvested for consumption as fresh fruit, it is best to pick them just before full maturity and carefully place them in smaller packages. It is best to use containers that hold around 120g (4 ounces) to not more than 500g (around one pound). Fresh blackberries kept in a cool, dark place can hold up to 4 days. If you grow blackberries in home garden, wait till they are fully ripped and consume them right after picking – within minutes!
It is best to harvest blackberries early in the morning or late in the afternoon to avoid the summer day's heat. Also, freshly harvested fruits should in no way be left in the sun – they will rapidly deteriorate, lose moisture and their glossy black appearance.
Note: for any home gardener, quality, taste and aroma of the picked blackberries should be priority, not the size! This is true for many berries.
Growing blackberries – Tips and Tricks
Here are few tips and tricks for growing strong and healthy blackberries that bear strong, healthy and great tasting fruits:
- avoid growing blackberries on positions where previously were grown plants like potatoes, tomatoes, raspberries, peppers, grapes, apples and peaches. These plants share similar diseases and pests with blackberries.
- blackberries should be grown on the positions on which previously grew plants like Sudan grass, wheat, oats or rye. If you plan on growing blackberries in large flower pots, it is best to use good, sterile, potting soil.
- blackberries like mulching - to prevent soil erosion, reduce moisture evaporation and prevent weeds to grow, spread mulch across the topsoil in your blackberry rows or pots. The best mulch for blackberries is mulch based on pine bark and wheat straw. Also, using black plastic foil is also recommended, especially if drip irrigation system is in place – be sure to protect black plastic foil with mulch, since such plastic is not very durable when exposed to strong sunlight. Organic mulch is preferred, since it slowly decompose and feeds the plants gradually and keep the pH factor in desired range (pH 5.5 – 6.5 for blackberries)
- if you take care of your blackberries, they will bear fruits for 15-20 years, some even more. Planning is very important before planting such long-lived plants.
Long Story Short - if you have small patch of soil in your garden, or you have space for few 60cm (2 feet) flower pots, grow blackberries - these plants will give you ample of healthy and tasty fruits, while leaves can be used for making great tea.
Blackberries, sometimes known as brambles, are very popular because of their sweet and slightly tart flavor. However, rather than buying them from shops, growing them in one’s own garden lets one enjoy plenty of freshly picked blackberries without a lot of effort. Especially if one lives in the U.S. Department of Agriculture plant hardiness zones 3 to 9 to which blackberries are hardy, they can have their blackberry plants thrive well and give big yields.
Blackberries are also easy to grow and maintain. Although there are multiple methods of planting blackberries, planting blackberry cuttings is perhaps the most reliable method of propagation if one takes softwood cuttings in early spring from offshoot growth.
Published: October 8, 2021.