How to Grow Raspberries
Raspberries are certainly an attractive fruit, both in terms of its rich red fruits and their awesome taste, due to which any gardener would want to plant them in their own garden. But the delicious taste of these berries is not their only quality; they are one of the healthiest snacks too, loaded with fiber, antioxidants, vitamin A, folate, vitamin C and minerals.
The best part is that raspberry plants produce an impressive number of fruits even in a small space and if the grower gives proper care, they go on yielding the same number year after year.
The berries can be harvested right from mid-summer up to the first frost. Here’s some information on how to grow raspberries.
Published: September 26, 2019.
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Based on fruiting-pattern, raspberries are classified in two types, each one with its own particular requirements for growing:
These are more common and develop their fruit on the growth of last year. They produce one crop per season, during summer (typically in June or July).
These are also known as fall-bearing or autumn-bearing raspberries. They produce berries on new growth. They produce a fall crop and may also bear fruit the following summer.
Growing a mix of both these types of raspberries would be a good idea to maximize the time of harvest.
All raspberries are self-fertile. Hence the grower just needs one bush to produce fruit and they will get a dozen or even more plants on the same site next year. The best pollination is done by bees. However, raspberries are energetic enough to breed by underground runners. The plants will start producing fruit after a year of planting.
Although raspberry bushes have a natural tendency to grow in cooler climates, nowadays the plants come in several varieties that are suited to a wide range of planting zones.
Primocanes and Floricanes
While raspberry plants live for several years, their canes are biennial, i.e. they live for 2 years.
These are first year of growth. Only fall-bearing raspberries generate a considerable amount of fruit on primocanes in the late summer and fall. Some primocane-fruiting (fall-bearing) cultivars are Autumn Bliss, Autumn Britten, Amity, Vintage, Anne, Caroline, Fallgold, Joan J, Jaclyn, Himbo Top, Polana and Polka.
This is second year of growth. Both fall-bearing as well as summer-bearing raspberries form fruit on floricanes. Fruit is produced on branches known as fruiting laterals. Floricanes die after fruiting. Some floricane-fruiting (summer-bearing) cultivars are Latham, Killarney, Cascade Gold, Cascade Bounty, Chemainus, Saanich, Meeker and Tulameen.
Classification Based on Colors
Based on colors, raspberries are mainly classified into two types – black and red. Yellow raspberries are a result of a mutation of red raspberries that stops the generation of red color. They are grown just same as red raspberries. A third type – purple raspberries – is a hybrid between red and black raspberries.
[‘Tayberry’, ‘Boysen’ and ‘Logan’ are hybrids between red raspberry and blackberry and are actually blackberries. In blackberries, the core is a part of the berry, while in raspberries, the core remains adhered to the plant when the fruit is harvested.]
Red Raspberries (Rubus idaeus)
These are native to northern North America and Eurasia. Red raspberry cultivation started in the United States as early as in 1771.
Red raspberries produce new canes from crown and from buds on roots. During the first year, canes are known as primocanes, while in the second year they are known as floricanes. They are pruned after the second year. Both primocanes as well as floricanes are present during the growth season.
Red raspberries again fall into two types – one is floricane-fruiting (summer-bearing) variety, in which the second-year floricanes produce a crop in early summer and the first-year primocanes are just vegetative. The other is primocane-fruiting (fall-bearing) which produces a considerable number of fruits at the top of the primocanes in the fall. An easiest way to manage primocane-fruiting raspberries is to prune the primocanes to the ground every winter after fruiting.
However, if they are kept for the second year, they will bear a crop on the floricanes the next summer. Since primocare-fruiting cultivars can be double-cropped, they are sometimes known as ever-bearing raspberries.
Black Raspberries (Rubus occidentalis)
Sometimes known as blackcaps, black raspberries are native to an area from the Northeast to the Great Plains. R. leucodermis is the native western black raspberry.
Black raspberries form canes only from the crown, and not from the roots. Primocanes should be tipped in summer to trigger branching. These canes will give fruit in the following year.
There were dozens of cultivars of black raspberries in the early 1900s and until around the 1960s, new cultivars were being invented. However, recently breeding work on black raspberries has been reduced and only a few cultivars are now commonly available. Almost the entire commercial crop in the Northwest is “Munger”, a variety introduced in 1890.
These are a hybrid between red and black raspberries and tend to be prolific, crown-forming plants with soft, large fruits. These raspberries are usually thought to have only fair quality for fresh use, but they are perfect for processing.
Why is Pruning Important?
All raspberries should be pruned annually. Raspberries are perennials. Still, it should be remembered that their canes (or branches) which bear the berries live only for two summers.
During the first year, primocane or the new green cane grows vegetatively. It’s dormant in the winter and develops a brown bark. During the second growing season, it is known as floricane. This produces fruit in early to mid-summer and then dies. Each year new primocanes are produced and thus fruit production continues for years. It’s the job of the grower to prune out those dead canes every year. (More on pruning below)
Recommended Raspberry Varieties
Today numerous varieties of raspberry are available and each of them is unique. Various raspberry varieties thrive from Zones 3 to 10. It needs some homework to find the right raspberry variety for one’s location. Even one can inquire at one’s local garden center or agriculture office about which raspberry varieties are best-suited to their area. One should take time in selecting because raspberries come in a variety of colors (red, yellow or golden and purple), sizes and shapes. Here are some of them ideal for beginners.
This is a summer-bearing variety bearing purple berries and is recommended for warmer areas.
This is an ever-bearing variety with yellow berries that are tingled with peach. It’s recommended for warmer areas.
This is an ever-bearing variety producing yellow berries and is recommended for Upper Midwest and Canada.
This is an ever-bearing variety producing red berries and thrives especially at higher altitudes (High Plains and the Rockies).
This is an ever-bearing variety producing red berries and is recommended for Ohio Valley and Mid-Atlantic.
This variety has red berries. It’s summer-bearing, almost without thorns, recommended for Upper Great Lakes, New England and Northwest
This is a summer-bearing variety bearing black berries and is heat- and drought-hardy.
This too is a summer-bearing variety, bearing black berries. It’s disease-hardy and is ideal for warmer areas.
Although some growers choose summer-bearing varieties, ever-bearing varieties are more popular for a reason. With an ever-bearing variety, the grower is able to harvest the berries every day until frost, eat them to their heart’s content, freeze some for winter and even give to neighbors and birds. On the other hand, summer-bearing varieties produce fruit only for around a month after which all is over until next year.
When to Plant
Planting should be started with one-year old raspberry canes which should be bought from a reputable nursery. These should be planted in early spring after the ground thaws out and becomes workable (local frost dates should be checked). Although raspberries can be planted in summer, those planted in early spring will establish better and can give a few berries in their first summer.
If the area is mild, planting can be done even in late autumn so that the plants can get a head start.
Potted transplants should be planted in the spring once the risk of frost has passed.
Finding and Preparing the Planting Site
A site that receives significant amount of sunlight is the best for raspberries. However, unlike many other fruits, raspberries also grow well in a partially shaded site. But the more sun, the more will be the fruits.
Soil should be rich and well-drained with good air circulation and shelter from the wind. Wet and windy area should be avoided since raspberries neither like to have its feet wet nor totally dried out.
Another option is to build a raised bed with a height of around 20 inches and fill it with peat, sand and well-rotted manure. This can be done in the fall, so, the soil is ready for planting at around next spring.
If the soil is acidic, growers will have to add some lime because the most preferable pH of raspberries is around 6.0.
But if the soil is rich and deep that drains well throughout the year, raspberries can be simply planted in a permanent site.
In areas that receive rains all through the winter, several gardeners lose raspberries due to root rot because they make a mistake of planting their raspberries directly in the ground, which is usually damp clay covered with a layer of topsoil. In such a condition, raised beds are useful because they allow growers to have deep soil that is wet evenly yet drains well.
Plants should be fed every year with a couple of inches of aged manure or compost; this should be done a week or two before planting too. Around 3 ½ cubic feet of compost per 100 sq. feet is a good rate.
Raspberries should be planted far from wild growing berries; otherwise, there is a risk of wild pests and diseases spreading to the cultivated plants.
It’s also important that the raspberry patch should not be established in an area where previously plants like potatoes, peppers or tomatoes have been grown. This is to avoid verticillium wilt, a fungal wilt disease, that these vegetables may carry and raspberries can catch.
How to Plant
Before planting, the roots of the raspberry plants should be soaked in a half-strength solution of ½ teaspoon of vitamin B1 growth stimulant per quart water for almost six hours. After this, planting should not be delayed because the small plants will not tolerate soaking longer than a day in the solution and will die soon with dry roots.
If grower receives dormant bare-root plants before they are ready to plant, the plants should be put in refrigerator to keep them dormant.
While planting, the grower should keep some things at hand such as compost, well-rotted manure or mushroom manure, organic fertilizer or 4-20-20, some mulch and a water source.
Then a 1-foot deep and wide hole should be dug per plant on the chosen site of planting. The hole should be spacious enough to allow roots to spread. While planting multiple plants, it’s easier to dig a trench.
Whether the plant is potted or bare-root, its crown should be kept 1-2 inch above the ground.
There should be a space of around 3 feet between canes, while rows should be around 4 feet apart.
Now a handful of fertilizer and rotted manure should be put in the hole and then the soil should be filled back and tamped down with feet. Then some more rotted manure can be sprinkled at the surface which will give the plant a jump start for growth. Then the ground around the plant should be covered by mulch, but not more than 3 inches deep.
Once the canes are planted, they should be cut down to 9 inches tall to identify new growth. (This will appear like a broken branch sticking out from the ground).
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A raspberry plant loaded with berries becomes top heavy and should be given a support to save it from falling over. Several grow to head-height. A fence or trellis is a good idea. If there is a row of plants, two 6-foot posts should be installed on each end of the row and galvanized wires should be stretched between them. Fall-fruiting varieties need two wires, whereas summer types need three.
The ideal way to water raspberries is drip irrigation.
Taking Care of Raspberries
It’s important to mulch all through the season in order to maintain moisture and choke up weeds. All the time, a layer of mulch should be maintained around the plants.
Plants should be watered one inch per week from spring till after harvest. Regular watering is better than occasional deep soaking.
Bushes should be tidied up by digging out any canes or “suckers” growing away from the rows; if they are not dug out, they will soak up nutrients from the main plants and there would be fewer berries next year.
Suckers can also be replanted to get new plants. For this, they should be dug out and planted in a fresh area of prepared ground and watered after planting.
Summer-fruiting raspberries should be pruned right after harvest. Only the canes that produce berries should be cut back down to the ground.
It should be remembered that this plant bears berries on two-year old growth whereas one-year old canes grow just beside them. It’s not difficult to identify which is which. The older canes will have brown stems, while the young ones will still look green. The older ones that have finished their fruitful year should only be pruned.
Remaining canes should be tied with a garden string to the supporting wires. However, there should not be more than one cane every four inches of wire. If there are more canes, they should be cut down.
Fall-bearing or Ever-bearing Raspberries
Pruning fall-bearing raspberries is easy. All the canes should be cut back to the ground in late winter prior to the beginning of growth in the spring. Canes that are in their first year of growth bear fruits after which there is no use to keep them. They should be mowed to the ground or pruning shears should be used for a small patch.
All debris, pests and diseases should be cleaned up.
Pruning is not needed during the growing season unless the grower wants to maintain a uniform order.
NOTE: The above tips are for a fall crop. For both fall and next summer crop, primocanes that produced the fall crop should not be removed. They should be pruned back to around 12 inches above the support or to the last apparent node that had fruit, in spring. Dead tips should be cut off.
Balancing between Dampness in Summer and Dryness in Winter
To keep raspberry plants healthy and prolific, they should be saved from drying out in the summer. It should be remembered to keep them damp in summer and dry in winter.
Straw or other mulch should be spread around the roots to maintain sufficient moisture. If the grower doesn’t have a drip system, a soaker hose for a couple of hours per week can do the trick. In forthcoming years, the freshly pruned plants should be top-dresses with several inches of fertilizer, well-rotted manure and if needed, a sprinkling of lime.
A considerable amount of nitrogen is needed by raspberry plants to grow to their full height of 6-7 feet.
However, they should not be loaded with high-nitrogen fertilizer once fruiting time approaches. It’s because at this time, the focus of the plants should be on producing fruits rather than producing leaves. At such times, homemade organic fertilizer offers the required nutrients to the plants.
Diseases and Pests
Only a few fruits are not much bothered by diseases and pests and raspberry is one of them (Here too it should be remembered that black raspberries are more vulnerable to this kind of damage than purple or red).
- From Jun to August, the plants should be carefully watched for Japanese beetles and spider mites. Japanese beetles particularly like raspberries. Aphids can be eliminated with a steady blast from a hose, while Japanese beetles can be removed by hand. Birds can be kept away by installing a net.
- During winter, growers should keep an eye on rabbits. A chicken wire fence can help prevent rabbits.
- Sunburnt fruit can also be an issue with raspberries and appears as a white spot; but it’s just cosmetic. If there is sunny and hot weather while the fruits are ripening, they can be covered with a shade cloth.
- Root or bud weevils
- Fruit worms
- Cane borers
- Powdery mildew
- Root rot leads to sudden death of plant immediately after flowering when the weather becomes warm. Most raspberry cultivars are prone to Phytophthora root rot. This disease is more prevalent in southern Washington and Oregon than in northern Washington and British Columbia. The only solution to this is to plant resistant varieties in well-drained, friable, rich soil.
- Fruit rot is a fungus that steps in when canes are excessively crowded. Hence, its remedy is openness and frequent picking in wet weather. Overhead watering should be avoided and fruiting canes should be pruned after harvest.
- Spur blight is seen in the form of dark-chocolate colored blotches on primocanes in the period of mid-summer to fall when moisture is high. Overwintered canes look silvery gray and develop millions of spores. Good air circulation should be provided and lime-sulfur solution should be applied.
- Raspberry bushy dwarf virus (RBDV) is a pollen-borne virus (carried by bees); its main symptom is friable fruit. The infected plant looks normal, i.e. neither bushy nor dwarf. There is no remedy to this problem other than to replace the plants with virus-free stock which should be resistant.
Natural Way for Healthy Pollination
Although raspberries are self-pollinating, bees like orchard mason bees can play an important role in their pollination as well as overall fruiting. A grower can build a home for orchard mason bees near raspberry plants, even on the supporting poles in the form of holes drilled in the poles with an overhanging shingle for a roof. Orchard bees come to live in the holes and do their job.
Any variety of raspberries will start producing fruits in its second season. In a few cases, ever-bearer may produce small fruits in their first autumn.
Berries will ripen in early summer over around two weeks. They will need to be harvested every couple of days.
Berries should be picked on a sunny day, when they are dry.
While picking, berries should not be tugged upon too hard. A ripe raspberry will come off easily.
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Raspberries don’t last long; so, they should be enjoyed soon after harvesting.
They can be kept in a refrigerator around 5 days. They should not be washed after picking unless one should be eating them right away. If they are washed and kept aside, they will develop mold and become mushy. If they are to be washed and stored, it should be made sure that they are completely air dried before storing.
Raspberries can be frozen. While freezing them, they should be arranged on a cookie sheet in a single layer. After frozen, they should be placed in airtight bags. They can be used in cereals, on waffles, or wherever a healthy refreshing snack is needed.
Raspberry plants are beautiful to look at and produce delicious and healthy fruits. Hence a gardener should essentially plant them to make their garden look stunning and healthy at the same time.