If it’s your first time planting raspberries, you’re probably wondering if they spread, and if so, how far and how fast. Knowing what to expect from raspberries will help you to plan ahead for your garden.
So, do raspberry bushes spread? Raspberry bushes spread in 3 ways: by seed from the berries themselves, by canes touching the ground to form new roots, and by underground lateral roots. In ideal conditions, raspberries will spread to take over a large area, and may even be considered invasive.
Of course, if you don’t want your raspberries to spread, there are ways to stop it from happening. Proper maintenance will go a long way in keeping raspberry plants healthy and under control.
In this article, we’ll explore the ways that raspberries spread. We’ll also take a closer look at ways to prevent raspberry bushes from taking over the whole garden.
Let’s get started.
Do Raspberry Bushes Spread?
Raspberry bushes do spread, and they can cover a lot of ground in a short time! Raspberries will spread even faster if you do not support them properly and prune them each year.
Growing conditions will also play a big role in how far and how fast raspberries spread. Raspberries grow best in the following conditions:
- Temperature: 70 to 75 degrees Fahrenheit (21 to 24 degrees Celsius)
- Watering: the soil should stay moist, but not soaked
- Soil: a pH between 5.5 and 6.5 is ideal, with plenty of compost for nutrients.
Regardless of conditions, there are a few different ways that raspberries can spread.
How Do Raspberries Spread?
Raspberries spread quickly because they have 3 different ways of reproducing:
- By seed (the berries)
- By touching the ground (the canes)
- By underground expansion (the roots)
It is possible that a plant may use all 3 of these methods to spread in any given year. Even without help from people or animals, raspberries are quite skilled at spreading far and wide in a garden or in the wild.
Let’s explore the ways raspberries can spread, starting with the one we are most familiar with: by seed.
When you eat raspberries, there is the soft, juicy flesh and then there are the tough, fibrous seeds. Even though they are small, the seeds have everything they need to grow into another raspberry plant.
When a ripe raspberry falls off of a cane, it can grow wherever it lands. Growth is more likely if the seeds get covered by leaves and other organic matter that can decompose to provide nutrients for the new plant.
When animals such as birds eat raspberries from a bush, they also help the plant to spread its seeds. Some of the seeds will pass through an animal’s body system undigested.
The animal waste then provides an excellent manure to give the new plants a dose of nitrogen and other nutrients for growth!
According to the Cooperative Extension, raspberries do not develop true to seed. In other words, any raspberry plants that grow from seeds may not share the same characteristics as the parent plant.
That could mean differences in fruit quality (flavor and yield) or other traits. However, as long as they can reproduce this way, raspberries are happy to do it!
By Canes Touching the Ground
Raspberries do not need to use their seeds to spread. They can also reproduce when their canes touch the ground.
“Although black and purple raspberries do not send up new primocanes outside the hill, they can spread. The long, vigorous canes often arch down to the soil surface, where they may take root. It’s important to keep the canes controlled and supported to prevent this.”https://extension.umn.edu/fruit/growing-raspberries-home-garden#planting-and-caring-for-new-plants-697310
Basically, raspberry canes can spread rapidly when they grow wild (this could happen in your garden without proper care!) With no support and no pruning, raspberry canes will grow tall and eventually bend over towards the ground.
When this happens, they will crawl along the soil, advancing until they find a suitable spot to put down new roots. At that point, the raspberry cane will produce a “sucker”.
A raspberry sucker is a new plant with its own developing root system. If you wish, you can separate a sucker from the mother plant by cutting the end of the cane just above the sucker.
When cutting a sucker, use a sharp, clean knife. Washing the knife with alcohol before and after cutting will prevent the spread of any diseases that may be present.
After cutting the sucker away from the mother plant, you can transplant it to a new location. This could be at the end of a row of raspberries to increase your crop in later years.
You could also start an entirely new row, or make a gift of the new plant to family or friends.
By Suckers from Roots
Using seeds and canes to spread is impressive, but raspberries aren’t done yet. They still have one more trick up their sleeves: spreading underground by their roots.
This is a raspberry plant’s sneakiest way of spreading, and it is also a very effective method. Even if you support and prune your raspberry canes to keep the plants neat, they can still spread underground by using their roots.
The worst part is, you won’t see them until they come up in the spring. At that point, you could have a lot of digging and transplanting to do in order to keep your raspberry rows neat!
“Each spring, plants produce canes from buds on the crown and underground lateral stems.”https://extension.unh.edu/resources/files/Resource000010_Rep10.pdf
This means that in addition to canes coming up from the crown (base of the plant), a raspberry plant can also send up new growth from its roots after they grow sideways to expand into new territory.
However, red raspberries are the only ones in the family capable of this trick. According to the University of New Hampshire Extension:
“Purple and black raspberries and blackberries only produce suckers from the base of the crown and will not fill out a hedgerow as red rasp-berries do.”https://extension.unh.edu/resources/files/Resource000010_Rep10.pdf
Don’t worry though – if you want, you can still make more black raspberries by tip layering. According to the New Mexico State University:
“Because black raspberries don’t sucker as prolifically as red raspberries, they are usually propagated using a technique called “tip layering.” Tips of new black raspberry canes produced in the summer can be buried in the soil (3–5 in. deep) in the fall. Firm soil around the tips and water. Rooted tips can be severed from the mother canes (leave 4–6 in. of the original cane with the roots) the following spring and transplanted to their new locations.”https://aces.nmsu.edu/pubs/_h/H320/welcome.html
How Far Will Raspberries Spread?
As you can see, there are lots of ways for raspberries to spread and propagate their species all over your garden. So, how far will raspberries spread in their quest for yard domination?
When spreading by seed, raspberries can spread anywhere that you or any animals drop the berries (seeds). If you pick berries and toss the unpalatable ones aside, the seeds from those culled berries could grow to become new plants.
If an animal eats raspberries and leaves its waste somewhere else, plants could also grow there. As you can imagine, there is the potential for raspberry plants to travel far and wide just from their seeds!
When growing from suckers or from the root system, raspberries will spread in a slow but steady manner each year. They will colonize soil close to the mother plant to produce new plants and progress from there.
The next year, the mature canes will repeat the process to continue spreading. Since raspberry plants can live for 15 years or more, there will be an overlap between many generations of plants.
How Do You Keep Raspberries From Spreading?
There are a few ways to keep raspberries from spreading. There isn’t much you can do about animals spreading the seeds after eating the fruit, but 3 things you can do are:
- Tying canes to a support
- Pruning the canes
- Using a root barrier
Let’s start with support for raspberry canes.
Tie Canes to a Support
When you tie raspberry canes to a support, you keep them from hanging down and touching the ground. This prevents them from producing suckers when they come in contact with the soil (as described above).
There are a few different ways you can support raspberry canes.
Using stakes is one way to support an individual raspberry plant. You can use twine to tie multiple canes to a stake as they grow taller.
You can use stakes made of wood, metal, or plastic, depending on what is available. You can learn more about garden stakes (and their uses) in my article here.
Remember that you will need to install a stake for each plant in your row of raspberries. With a long row of plants, it will be more efficient and cost-effective to use a trellis.
You can buy or make a traditional trellis (with a lattice pattern) made from metal, wood, or plastic. You can learn more about trellises (and the materials you can use to build them) in my article here.
However, buying or building a traditional trellis might not be cost effective for a long row of raspberries.
Instead, you can drive stakes deep into the ground at either end of a row of raspberries. Then, run a length of wire or twine from one stake to the other, tying each end to one stake.
Put a length of wire at varying heights – perhaps every foot or so. As your raspberry canes grow taller, you can use twine to tie them to the next highest length of wire.
You can always move the stakes further out if you decide to transplant more raspberry bushes (from suckers or from new plants you buy) to extend your row.
An arbor is another option for supporting raspberry canes. An arbor is often used to provide shade and shelter in a garden, or to improve the appearance of a garden.
You can let raspberries grow up one side of an arbor and down the other side. Then, you can pick berries in the shade as you walk underneath the arbor.
Prune Canes and Pull Up Suckers
Pruning your raspberry canes will keep them healthy and promotes new growth. Healthier plants will lead to more fruit every season, and the plants will be easier to manage.
Pruning raspberries will also prevent the canes from getting too long and touching the ground. This will help to prevent new suckers from forming where the canes touch the soil.
Despite using support and keeping plants pruned, sometimes a few stray canes will find their way to the soil and produce a sucker.
In that case, you will need to do the work of cutting them from the mother plant and digging them up. You can replant them at the end of the row, give them away, or just dispose of them if you don’t want them.
Use a Root Barrier
Even with proper support and pruning, raspberry plants can still spread by sending up new growth from lateral roots.
However, you can stop them from spreading this way by using a root barrier. A root barrier is any material that stops the roots of a raspberry plant from spreading beyond than the barrier.
A root barrier should be solid, without any holes for the roots to go through. It should also be thick enough to prevent roots from breaking through, and strong enough to avoid rotting.
Before you install a root barrier, you will need to dig a trench along the row of raspberries.
Best Root Barriers for Raspberries
There are several materials you can use as a root barrier for raspberries, including:
- Metal – aluminum flashing is one option that is not too heavy and will last for a while.
- Wood – untreated wood will eventually rot, so it won’t last as long as metal. However, you can always replace the wood and then compost or burn the leftover material.
- Rocks – these are free, but it might be hard to arrange them so that it is impossible for roots to get through. However, a good layer of rocks will stop most roots from getting through, or at least slow them down.
- Landscape fabric – this is a temporary solution, and probably won’t do much to stop roots in the long term. However, it could be a good supplement to using rocks, since you can cover up any holes between the rocks.
Now you know how raspberry plants spread, and how you can stop it if you want to keep them contained in one area of your garden.
I hope you found this article helpful. If so, please share it with someone who can use the information.