There’s nothing like having healthy raspberry plants. Raspberries are hardy plants that can survive through frost as long as they have not yet bloomed.
Blooming raspberries need protection from unexpected frost. Protect raspberries from frost using 4 frost-beating tips outlined in this article.
Raspberries grow interestingly: canes are biennial while the roots are perennial. So, after the second year of fruit-bearing, the canes die while the roots remain.
In the first year of growth, the canes grow leaves but no fruit. Next year, berries will appear.
By the end of the article, you should know the different classes of raspberries, how frost hurts raspberries and how to prevent frost damage in these plants.
Raspberry varieties are classified based on whether the fruit is produced on canes that emerged in the current season (primocanes) or on canes of one year (floricanes). Therefore, there are two types of raspberry varieties:
- Primocane-bearing raspberries also called fall-bearing raspberries
- Floricane-bearing raspberries also called summer-bearing raspberries
Primocane raspberries bear fruit on the current season’s growth; in other words, on canes that started growing that year. Harvesting begins in late summer and lasts until the first hard frost in autumn.
Primocanes are easier to cultivate than floricanes and are more susceptible to frost.
Floricane raspberries are also called summer-bearers because their fruit ripens in the summer months. They should be trellised using wire supported by wooden or metal posts. They are not as prone to frost as fall-bearing raspberries.
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Does Frost Hurt Raspberries?
Yes, frost can hurt raspberries depending on the severity and duration of exposure.
Long periods of cold and repeated exposure to frost, increase the chances of raspberries getting damaged. The level of injury is directly related to the harshness of the frost.
Some varieties of raspberries are more cold-tolerant than others. For instance, floricane raspberries need a lot more protection from frost than Caroline raspberries.
The hardened first-year growth, protected by the tough layer of bark around the tube, survives light winter frosts unscathed. But the delicate new growth of the canes in early spring is vulnerable to late frosts and cold snaps.
In general, red raspberries are colder resistant than black raspberries, making them better suited to cooler climates. Remember that the temperature on the ground can be up to five degrees lower than the forecast temperature in your area and cover plants accordingly.
Frost-damaged raspberry bushes produce raspberries that are wrinkled or may turn white. The leaves would be smaller than normal and dry up easily in the sun.
Some canes may be affected while others are not. It is expected that the affected canes will die and the remaining ones will survive.
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When Should You Protect Raspberries from Frost?
As soon as the first signs of frost appear, steps should be taken toward protecting raspberries from frost. However, it may be beneficial to allow your raspberry to experience one short season of frost.
You may find that your raspberry canes have begun to improve after the first frost. If the temperature is below -1 degrees, it is time to offer protection to your bushes.
Once raspberry canes have been damaged by frost, there is very little you can do to save them. You will have to remove them with pruning shears.
It will save you a lot if you are on the lookout for frost predictions in the news.
How to Cover Raspberries from Frost
Raspberries can tolerate mild frost, for a short time. But repeated freezes for extended periods will begin to tell on them.
Here is how to cover raspberries to protect them from frost (4 frost-beating tips):
1. Plant raspberries near the wall
Raspberries are tall plants which often need support as they grow. Trellises and fences provide this support perfectly.
Apart from the support they offer, they also protect raspberries from harsh draught, essentially protecting them from frost.
Suspending your raspberries off the ground keeps them from getting damaged by icy soil. This will protect raspberries from frost.
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2. Cover the plants with fabric
Use blankets and sheets to cover your raspberry plants. This is a great way to protect raspberries from frost.
The goal of using fabric to cover raspberries is to trap a layer of warm air around the bushes. As you use fabric, do not allow them to touch the plants beneath.
If the covers are in direct contact with the plants and become wet and frozen themselves, that can be transferred to the plants below. This may also infect the plants with fungus.
One can also choose to use a thermal blanket.
3. Cover them with soil
After the last of the berries have been harvested for the season, prune canes that are up to two years old. Trim the canes that are left on the bushes.
Now, bend the one-year-old canes left into the ground gently and cover them with soil. This layer of soil should measure about seven and a half centimetres in height.
Mulch can be used to achieve this instead of soil. It is all down to personal preference.
You can remove these from the soil once spring begins so that they can sprout again.
4. Use heat lamps in the garden
Use heat lamps in the garden if it is close to an electricity source. You can switch them on and off when you need to and they can provide warmth for your raspberries, protecting them from frost.
As you use heat lamps, keep them out of direct contact with the plants. Hang the lamps on stakes at a respectable distance from raspberry bushes (at least 13cm).
Additionally, mulching techniques can protect raspberries from frost. Mulch creates an insulating barrier on the soil, keeping frost and bay and trapping some warmth.
You are now aware of some of the more cold-tolerant varieties of raspberries and how to provide a little extra cold protection for your plants. Protect raspberries from frost using the several methods explained above.
It pays to take good care of a raspberry bush, as the best bushes can survive in the garden for many, many years. Think of how many jars of jam you will enjoy in that time!