How to Grow, Prune and Propagate Raspberries

Raspberries (Rubus idaeus) belong to the genus Rubus, along with other cane berries such as blackberries, boysenberries, lawtonberries, loganberries, marionberries, silvanberries and tayberries.

What’s quite interesting is that the whole Rubus genus is part of the Rosaceae (Rose) family, to which almonds, apples, apricots, cherries, hawthorns, loquats, peaches, pears, plums, quinces, raspberries and strawberries also belong!

One identifying characteristic of raspberries is that when they’re picked, the receptacle, which looks like a small long white plug, remains on plant, leaving a deep hole at the top of the berry. Other cane berries such as blackberries and their hybrids don’t have a long receptacle and detach cleanly at the top leaving only a small indentation where they were attached.

The growth habit of raspberries differs from the other cane berries too. Raspberries have vertical upright canes around 1-2m long, and their suckering shoots tend to run and pop up quite a distance away from the original plant, whereas other cane berries stay in a clump where they’re planted, and have much longer trailing canes that tend to grow more horizontally and root into the ground where they make contact with the soil.

Even though raspberries are perennial plants, only their underground root stems and crowns are perennial. The canes which grow from underground buds are biennial (living for two years). The first year canes (referred to as primocanes) only produce leaves, two-year old canes (which are called floricanes) produce flowers and fruit, and then die back. These two year old canes are pruned back to the ground after all the berries are harvested to keep the plantings tidy.

Raspberry Varieties

The red raspberry (Rubus idaeus var. idaeus) is the most common raspberry variety, but there are other varieties and hybrids available with berries that are yellow, orange, purple or black in colour.

Even among the red raspberries, there are many varieties which differ in their cropping seasons as well as the size and flavour of their berries.

In terms of cropping seasons, there are three types of raspberries:

1. Summer-bearing types – early cropping varieties, which produce their crop in summer
   
2. Autumn-bearing types – late cropping varieties, which produce their crop in autumn
   
3. ‘Everbearing’ types – long cropping varieties, which produce over many months, producing a large main crop in summer, and a smaller second crop in autumn.

Raspberry Growing Requirements

Soil – Raspberries prefer soils which are moist but well-draining, slightly acidic to neutral soil (with a soil pH of 5.6 to 6.2) and rich in organic matter.

They’re best planted in late winter to early spring as this gives the plants plenty of time to establish themselves before they encounter hot summer weather.

Before planting raspberries, dig in plenty of manure to increase soil fertility, and add compost to increase organic matter and improve soil structure.

These plants cannot tolerate heavy, wet clay soils which will cause root rot. To improve drainage, dig compost into the soil. Gypsum can also be added as a clay breaker for sodic (sodium-containing) clays.

There’s no need to fuss about the soil pH if it’s close to neutral (pH 7), but in parts of the world where the soil may be very acidic it may help to add some garden lime or dolomite lime to reduce excess acidity.

Light – Even though raspberries are described as being able to grow in full sun to part shade, they don’t cope well with direct hot afternoon (west) sun, or exposed, hot windy locations. Such extreme conditions cause the leaves burn and the fruit to overripen very quickly. The ideal growing location for raspberries is an area which receives morning and midday full sun, and dappled sun or part shade in the afternoon. Don’t plant raspberries in shady locations as they won’t bear much fruit.

Watering – The root systems of raspberries are quite shallow, growing only in the top 60cm (2’) of soil, so they need to be watered regularly in spring and summer. Mulching around the plants (using a straw-like mulch such as pea straw, lucerne, hay, etc) helps retain soil moisture and keeps roots cool in hot weather, and also suppresses weeds all year round.

Feeding – Since raspberries are heavy feeders, they need to be fed once at the start of spring and once again at the start of autumn with a balanced fertiliser. A good general purpose, slow release fertiliser, the type that comes as a powder or pellets, works well. Liquid fertilisers are only used for a quick supplemental feeding once a slow release fertiliser has already been used! If feeding with blood and bone or composted manure, which mainly provide nitrogen and phosphorus, use seaweed extract or potash (potassium sulphate) as well to add potassium which is required for flowering and fruiting.

Companion planting – Good companion plants for raspberries are tansy which is a general pest repellent, and garlic which repels aphids and protects raspberry roots from Japanese beetles. Avoid planting raspberries near blackberries because they’re very similar, but easily out-competed by the more vigorous blackberries. Don’t plant raspberries near strawberries or any members of the Solanaceae family such as potatoes, tomatoes, capsicum and eggplants, or in soil where they have been growing in the last three years, as these plants can transfer Verticillium root rot disease to which raspberries are susceptible.

Growing in containers – Raspberries will grow in a large container, pots and planters, but they will not be as productive as they are in the ground unless there is sufficient soil volume. The minimum pot size would be one that is 50cm (20”) wide, which has a volume of approximately 70 litres (18 US gallons), filled with a premium potting mix.

Training Raspberries Over Supports

Raspberries have upright growing canes, which need some kind of support to hold them up as they grow.

Here are three support systems which are commonly used for raspberries:

Single Fence System

This system uses two posts which are 1.2 – 1.5m (4’-5’) above the ground, driven 60cm (2’) into ground.

The posts are placed 2 – 3m apart, with 2mm galvanized wire (12 AWG or American Wire Gauge) strung between the posts at 50cm, 40cm, and 30cm (20”’, 16”, 12”) for a 1.2m (4’) high post.

Canes are tied to the wires with plastic-coated gardening wire twist ties, twine, plastic or fabric tree tie material.

Some sources suggest using posts 2m (6’) above the ground, but raspberries don’t need to grow that high, and rarely do so. Overly long canes can simply be tied down to the top wire, or cut, and keeping the support system lower makes it much easier to cover with fine 2mm insect-exclusion netting to keep birds out. Using a very fine mesh protective netting prevent tangling with the raspberry canes, and they can’t grow through it either.

Single Post System

This system uses posts to support plants without any support wires between posts.

Each individual plant with it’s clump of canes is tied to a single post, with 12 canes per post.

The posts are 1.5 – 2m above ground, and driven 60cm into ground.

If plants sucker and new shoots arise from the soil between posts, they must be dug up and replanted beside a post to keep this system tidy.

Double Fence System

This system uses two posts 1.5 – 2m (5’ – 6’) above ground, driven 60cm into ground.

Each post has two horizontal cross bars which are 60cm (2’) long fixed at heights of 1m (3’) and 1.5m (5’) above the ground.

2mm galvanized wire (12 AWG or American Wire Gauge) is strung from the ends of cross bars, and short wires are attached as cross ties perpendicular to the main wires every 60cm (2’) along wires.

The double-fence system uses a lot of materials, is complicated to build, and doesn’t really provide any additional benefits, so it’s essentially pointless. A single fence system is more than sufficient for supporting raspberry canes.

If planting multiple rows of raspberries, the orientation of the fence systems to the sun are important.

It’s best to plant the rows running north-south so plants receive even sunlight, and don’t shade each other out.

Remember to protect the raspberry plantings from hot afternoon west sun.

What Age Canes Do Different Raspberry Varieties Fruit On?

It’s important to understand how the different varieties of raspberries fruit, because raspberries are pruned after they finish fruiting, and if the wrong canes are pruned away, the season’s crop will be lost!

All raspberry plants are perennial, their crowns and roots are perennial (living many years), but individual canes are only short-lived. The life of the canes and when they fruit differs with the different raspberry varieties.

How Summer Bearing Raspberries Fruit

The canes of summer bearing raspberries live for two years.

In the first year:

In spring, summer bearing raspberry plants produce new canes (known as primocanes) from buds on the crown and from underground lateral stems.

The primocanes of summer bearing raspberries produce only leafy green growth in the first year, then they overwinter (survive through the winter to grow for a second year).

In the second year:

• the year-old primocanes turn into fruiting canes (known as floricanes) and produce fruit during the summer, and die back shortly after fruiting.
  
• around springtime, new primocanes emerge, which will bear fruit in following year.

How Autumn Bearing Raspberries Fruit

The canes of autumn bearing raspberries live for one year.

In spring, autumn bearing raspberry plants produce new canes (known as primocanes) from buds on the crown and from underground lateral stems.

The primocanes of autumn bearing raspberries grow and produce fruit in the same year, in the first year.

How Everbearing Raspberries Fruit

Everbearing raspberries share the fruiting habits as both the summer bearing and autumn bearing varieties, and their canes survive for two years.

These overbearing raspberry varieties produce fruit on the tips of first-year canes in autumn, and then produce a larger summer crop on the lower portion of these same canes in their second year.

How to Prune Raspberries

There are two different pruning techniques used for raspberries, one for summer bearing varieties and another for autumn bearing varieties. This is because they fruit on different aged canes.

• Summer bearing raspberries fruit on floricanes, fruiting canes formed in the second year.
  
• Autumn bearing raspberries fruit on primocanes, new canes produced in the same year.
  
• Everbearing raspberries fruit on the tips of first-year primocanes and on the lower portion of second-year floricanes.

How do we distinguish first-year canes from second-year canes?

First-year canes have green stems, while second-year canes have a thin, brown bark covering them.

Pruning Summer Bearing Raspberries

When raspberries are first planted, they’re usually year-old primocanes.

With summer bearing raspberries, in the next year, these primocanes will become floricanes, which are the darker fruiting canes with a thin brown bark, and new thinner green primocanes will emerge from the base of the raspberry plant.

After the older floricanes have finished fruiting in summer, cut them back to the ground, and tie the new primocanes to the support for next years fruiting.

Pruning Autumn Bearing Raspberries

When raspberries are first planted, they’re usually year-old primocanes.

Raspberries are typically planted in late winter to early spring, and with autumn bearing raspberries the primocanes will fruit in the same year, when the autumn season arrives.

Pruning autumn bearing raspberries is very simple, just wait until late winter and cut all canes to the ground. New canes will emerge in spring to replace them, and these are tied to the support structure as they grow.

Pruning Everbearing Raspberries

Everbearing raspberries are pruned in exactly the same way as summer bearing varieties, using the same two-year cycle. The only difference being that pruning is carried out in winter, after the second autumn crop has finished.

How to Manage Raspberry Suckering

Raspberries are vigorous growers, and they will sucker! They produce runner or stolons, which are horizontal running underground stems that will move out to other parts of the garden, which root and shoot to produce more raspberry plants.

They can be contained by using root barriers, but that approach can get quite expensive and involve a fair bit of digging. The other alternative is to simply dig up any suckers and replant them back along the support structure with the rest of the raspberry plants.

By digging up any suckering plants and replanting them, it’s possible to increase plant numbers significantly to create a very large and productive raspberry patch.

Propagating Raspberries

All bramble berries, including raspberries, can be grown from cuttings, and they can also be propagated by dividing up the parent plant when new canes form, as many canes will have their own separate roots.

To propagate raspberries from cuttings in late winter, cut a piece of raspberry cane around 20cm long, and cut the lower end at an angle to identify which is the bottom end and to make it easier to push it into the ground. the end can be dipped into rooting hormone if desired. Push the cutting into the ground so that the lower 2/3 is below the soil, with the top 1/3 above the soil. Wait till spring and the cutting will root and produce new shoots.

Should you use floricanes or primocanes for raspberry propagation?

The USDA, referencing “The Complete Book of Plant Propagation” by Jim Arbury, suggest using hardwood cuttings to propagate raspberries, and that the cuttings should be propagated in a site out of full sun and sheltered from drying winds. This would suggest using floricanes, as they’re a year old and have hardened off.

The best method for propagating raspberries is by division, which is usually carried out in early spring when the new canes form and suckers pop up some distance from the parent plant. Dig out these new suckering plants and cut them free from the stolon or runner, the underground horizontal stem that connects them to the parent plant. These suckers will have their own roots and can be transplanted to form a new plants.

Division can also be carried out in autumn, as the plants are still growing and produce new roots.

Sharing My Experience Growing Raspberries…

I’ve been growing the Heritage everbearing variety of raspberries for many years now, they produce well from late spring to late autumn, which is from mid-November to the end of May in the southern hemisphere her in Australia.

I have two plantings of raspberries, which are 2.4m (8’) long, and are located at the edges of garden beds. They use a single fence system which is made of two metal posts or star pickets with wire strung between them. The structure stands around 1.5m above the ground. Since the trellis borders an existing bed with other plants growing in it, the raspberries take up very little space, probably a 30cm wide edge of the bed, and therefore make efficient use of vertical space.

In the two plantings I have a total of around 30 raspberry plants, which were all propagated by division from one single raspberry plant grown in a pot for a year. I planted 15 plants along each support structure, and once they established, each planting produced 3kg (6.6 lbs) of berries in the second year, together they produced a huge harvest of 6kg (13.2 lbs) of berries! The raspberry patch doesn’t only produce food though, it also produces valuable new plants.

A lot of new raspberry plants pop up around the main beds because they spread by runners. From a permaculture perspective, free plants produced by nature are a valuable resource which can be sold or given away to others to help create better food security in the community. In one year I think I must have dug up and given away at least 60 raspberry plants. As the permaculture ethical principles advise, share the surplus!

References:

1. University of Minnesota Extension, Growing raspberries in the home garden
2. University of Illinois Extension, Hortanswers – Small Fruit, Raspberry, Rubus ideaus and R. occidentalis
3. University of Illinois Extension, About Raspberries – Raspberry Facts
4. NC State University, North Carolina Extension Gardener Plant Toolbox, Rubus idaeus var. idaeus
5. University of Maine Cooperative Extension, Bulletin #2066, Growing Raspberries and Blackberries
6. The Complete Book of Plant Propagation by Jim Arbury, Taunton Press, 1997
7. U.S. Department of Agriculture (USDA) Plant Guide – American Red Raspberry, Rubus idaeus