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Propagating bamboo and installing rhizome barriers

Bamboo can be readily propagated in your garden, but it needs a rhizome barrier.
Credits: iStock/ Supersmario

Introduction

Bamboo is decorative and a good visual screen. But it is essential to remember a rhizome barrier, or the bamboo will grow rampant. The plant is extremely easy to propagate. Here are all the tips.

Bamboo forms lots of shoots that you need to keep an eye on.
Credits: MSG / Folkert Siemens

Bamboo in the garden

Bamboo looks striking in the garden and is also a highly practical plant: the evergreen stalks protect against curious onlookers all year round.

There are different species of bamboo. Some species require more sun, some less. The best location for bamboo is a place sheltered from the wind with a permeable soil. Always keep the area around the roots slightly damp. But do not allow waterlogging to develop. Otherwise, the bamboo roots may rot. A drainage layer underneath the plant provides good protection against this. This allows the water to percolate easily.

Maintain your bamboo by regularly checking for offshoots. Lots of bamboo species form these. New stalks grow out of the earth at the end of offshoots. This means a rhizome barrier is extremely important for bamboo. You can find out more about this later in the article.

Dig out the stalks and offshoots in the border area of the bamboo once a year. But do not throw the shoots away. You can grow new plants from these and use them in the garden or give them away as gifts.

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Rhizome and rhizome barrier
The bamboo rootstock is called a rhizome. It grows horizontally both under and over ground, sprouting bamboo shoots upwards and roots downwards. Bamboo spreads rapidly in all directions from its rhizome. To stem and control this growth, it’s important to install a “rhizome barrier” around bamboo at the same time as planting. These are 28 inch tall plastic barriers that are buried around the bamboo plant.
You can propagate bamboo by separating off the offshoots and planting them.
Credits: Friedrich Strauss Gartenbildagentur / NouN

Propagating bamboo step by step

With the proper tips, even gardening beginners can propagate bamboo. Just follow these step-by-step instructions.

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L: Length, W: Width, H: Height, D: Diameter
Step 1 4

Take offsets

The best time to take offsets is from February to the end of March. Afterwards they will grow new stalks. Then do not disturb the bamboo.

In the first step, carefully uncover the bamboo roots. You can also dig them out. Then cut off some strong offsets using garden shears, such as the EasyPrune from Bosch. These shears are reinforced and therefore cut through the thicker plant parts easily and cleanly.

If the offset is extremely strong, take it off with a saw, such as the KEO from Bosch. This will quickly and safely separate the plant parts.

Step 2 4

Cut the offshoots into pieces

Cut the removed offshoots into several pieces using garden shears. Each piece should have about two to three knots. These are the spots on bamboo that look like pinched parts. The fine roots branch off from here.

Step 3 4

Plant the pieces

Now push the pieces into the soil. They should stand at a slight angle in the substrate. Make sure that the eyes face upwards. These are the spots on which either the new stalks or rhizomes will grow in the spring.

Cover the pieces with a roughly 10 cm thick layer of mature compost. You can also plant the bamboo pieces in pots. If you water them regularly, the plants will soon form new roots and shoots.

Step 4 4

Propagating clump-forming bamboo species

You’ll need a rhizome barrier for bamboo species that form shoots, otherwise they will spread uncontrollably.
Credits: MSG / Folkert Siemens

Some species of bamboo are clump-forming. These include the garden bamboo, among others. You can propagate these species through division. This should also be done in the early spring. If you don’t manage to do this in time, wait to divide them until late summer or autumn.

It’s best to divide bamboo on a rainy day. Frosty, warm or sunny days are less suitable.

Using a sharp spade, separate off as large a piece of possible from the rhizome ball. The piece should have plenty of stalks. Remove about a third of the leaves from each of the individual pieces. Then water the root ball thoroughly and put the offsets into a prepared planting hole.

Remember again to always keep the soil around the roots slightly damp.

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Bamboo indoors and outdoors
If you have a bamboo with extremely strong shoots, you can use these for an interesting DIY project, for example by making a bed head out of bamboo yourself.

Install a rhizome barrier around the bamboo

Bamboo spreads very quickly if you don’t do something to prevent it. With a rhizome barrier in the soil, you can limit the area the plant can take up. It is important that you install this barrier immediately. If the bamboo has started to spread uncontrolled, it is difficult to contain it again. The rhizomes are very tough. If you forget even a single one, new bamboo will grow from it. With these tips you can lay the rhizome barrier properly and securely.

It is essential that offshoot-forming bamboo species have a rhizome barrier. These include, among others, the phyllostachys. With their rootstock, the rhizome, these plants spread more and more vigorously over time. Bamboo has such as strong desire to spread because this type of propagation is important to it. Many plants rarely flower and therefore do not form any seeds.

In contrast, other bamboo species grow in clumps. These only develop short offshoots. They do not require a rhizome barrier. These bamboo species include, among others, the Dragon Head Bamboo.

Use a rhizome barrier made from high-pressure polyethylene to halt the rampant rhizomes.
Credits: Flora Press/BIOSPHOTO/NouN

HDPE rhizome barrier

Bamboo rhizomes grow vigorously. They can only be hemmed in with a special rhizome barrier made from HDPE, high-density polyethylene. The rhizome barrier should be at least two millimetres thick.

Do not use pond liner or bitumen as a root barrier in the garden. The bamboo rhizome tips will easily penetrate these. HDPE is particularly firm and tough, so that it is difficult to cut even with very sharp shears. You can generally buy rhizome barriers as 70 cm wide rolls that are sold by the metre.

In addition to the rhizome barrier itself, you will need a special aluminium rail. You can use this to connect the beginning and end of the barrier. This will create a closed ring. It is best to overlap the root barrier connection point by 10 cm to 20 cm. Also, place the rail flush at the start and the end. This holds the closure particularly well. This prevents the rhizomes from growing into the overlap and finding a way out.

Both the depth and inclination are crucial when installing a rhizome barrier.
Credits: Friedrich Strauss Gartenbildagentur / NouN

Install the rhizome barrier correctly

Bury the rhizome barrier 65 cm deep in the soil. The top edge should protrude about 5 cm above the soil. This is not particularly attractive, but it is necessary. In this way, you can see immediately if a bamboo rhizome starts to grow over the top of the root barrier.

Install the rhizome barrier with a slight outward incline in the soil. So it has a slightly smaller diameter at the bottom that the top. If horizontal rhizomes hit the barrier, they will direct themselves upwards due to the incline. If the rhizome barrier is vertical in the bed, the rhizomes could grow further down and grow out under the barrier.

You should stick to specific distances to ensure that your rhizome barrier remains effective for a long time.
Credits: Flora Press/gartenfoto.at

The proper distance for the rhizome barrier

Leave your bamboo enough space to grow inside the rhizome barrier. For individual bamboos, the barrier should have a diameter of 150 cm to 200 cm. This leaves the plant enough space for its roots.

If a previously healthy bamboo plant in the garden causes you concern after a few years and develops yellow leaves, the rhizome barrier may be too narrow. This prevents the plant from getting enough water. This can lead to the rhizome growing deeper down and circumventing the rhizome barrier there.

Too little space can also lead to the to the pressure from the rhizome becoming so large that it jumps over the barrier.

If you install a barrier for a bamboo hedge, the distance of the rhizome barrier to the plants does not need to be as big. Because in this case, you are installing a barrier around the hedge as a whole, not each individual plant. This means the bamboo can spread out to the sides. Leave around 100 cm distance in this case.

Other decorative shrubs, such as the staghorn sumac, also have root offshoots and therefore also require a rhizome barrier.
Credits: iStock/Carmen Hauser

Other decorative plants with root offshoots

Bamboo is not the only plant that spreads vigorously in the garden. The staghorn sumac is also famous for this. If you cut off a shoot or cut its crown, even more child plants will appear. This is how the tree ensures its survival.

The sea buckthorn, raspberry, blackberry and blackthorn all do the same. However, these plants can be prevented from spreading with pond liner. A rhizome barrier is not necessary here.

If you want to know more about when you should do what kind of work in the garden, you can find out the best times for all the important tasks in our Gardening Calendar.