Bamboo is valued by gardeners for its unique aesthetic appeal. But it can be challenging to grow in Maine’s cold climate and, if not planned and managed properly, could potentially take over your garden.
The first thing you should know is that true bamboo is not Japanese knotweed, an invasive plant that looks similar to the hollow canes associated with bamboo. The two aren’t even related — bamboo is a grass, and Japanese knotweed, despite nicknames like Japanese bamboo and Mexican bamboo, is more closely related to buckwheat.
Even so, bamboo varieties like running bamboo are aggressive and can take over gardens. Here’s what you should know before trying to grow bamboo in Maine.
Why grow bamboo?
Bamboo is an attractive ornamental plant that gardeners often seek out to create a visual barrier on their property or add a specific feeling to their garden’s design.
“Many of our clients want to add bamboo to their property as a privacy screen,” said Jennifer Estrada, co-owner of New England Bamboo Co. in Rockport, Massachusetts. “It is a nice tall, dense, and evergreen option to hide a fence or just to give your yard a more private setting in an otherwise thickly settled neighborhood. Others might like bamboo as an accent specimen for their garden or to help create a zen feel.”
Matthew Wallhead, ornamental horticulture specialist and assistant professor at the University of Maine Cooperative Extension, said that bamboo can also be used to stabilize soil because of its fibrous root system.
“It’ll help prevent erosion, and then it will also help absorb excess moisture from soils,” Wallhead said. “Then, depending on the variety that you select, you may get usable bamboo canes. It might be a source of materials for yourself.”
The return may not be quick, though. Jessica Thurston has been growing bamboo in Portland for five years and has yet to see the results she expected.
“The clumping bamboo spreads very slow,” Thurston said. “Mine are growing in between two paved driveways, underneath maple trees. I decided it was OK to take the risk because it was a contained spot, but honestly, they are really disappointingly slow growing. If these things ever achieve the privacy wall I was planning for between me and the neighbors, I will be impressed.”
Bamboo may struggle to thrive in Maine’s climate.
“Cold Maine winters and [the] shorter growing season make many of the bamboos unlikely to survive in Maine,” Fish said. “Most are suited to hardiness zones 7 and higher and Maine is in zones 3 to 6. [Some] species supposedly survive in zone 4 or higher, but will not reach the heights they do in more southern climates.”
The specific conditions of your garden will also affect bamboo’s ability to thrive.
“If you plant in an area that is too exposed to the elements for the species you plant (for example, exposed to the high winds facing the ocean), the bamboo will have a hard time establishing a root system strong enough to support itself,” Estada said. “Different varieties of bamboo tolerate wind, temperature, humidity and soil conditions differently. You should inquire with a professional about planting conditions before planting anything.”
How to start growing bamboo in Maine
The easiest way to grow bamboo in Maine is through propagation. Make sure you are purchasing bamboo from a knowledgeable seller, ideally one that specializes in growing bamboo in your region.
“I’ve heard many stories of people buying what they thought was a clumping variety to find out a few years later that it has invaded their yard or worse, their neighbor’s yard. It is so important to know exactly what species you are planting,” Estrada said.
Thurston said that she had to purchase her bamboo plants online because they were not available locally. But Wallhead said to be careful from whom you purchase it if you do this.
“I would advise against just ordering plants from individuals online from sites like eBay or Craigslist,” Wallhead said. “That would be at your own risk.”
Bamboo is generally pest-free — Estrada said that it consists largely of silica, which inhibits disease and repels pests like insects and even deer — but if you are purchasing bamboo from out of state, you need to be wary of soil-borne pathogens and other insects.
“I would definitely minimize the volume of soil that you’re introducing,” Wallhead said. “Containers are really attractive for plants purchased out of state for this reason because they’re not going into the ground. There’s always the potential to spread weeds, insects or diseases. [I recommend] making sure to remove any weeds, brushing off the top part of the soil to minimize any weed seeds that might be in the container along with it, and if the plant is clearly in poor condition, to not plant it.”
Fish said that garden centers in Maine will sometimes have bamboo available seasonally.
Fish emphasized that he does not recommend growing running bamboos in Maine, especially in the warmer southern areas of the state where it could spread quickly.
“Running bamboos in the Phyllostachys genus like golden bamboo are very aggressive,” Fish said. “Their underground rhizomes spread the plants very quickly. The only way to prevent them from invading almost any open area is with a very heavy plastic barrier that is 30 inches deep and about two inches above ground. I would not suggest that anyone use running bamboos in their yards.”
If you are concerned about bamboo spreading, you may also consider growing bamboo in containers instead of a garden plot. However, you will need the proper infrastructure to do so successfully.
“Planters need to be deep enough so there is enough soil for a strong root system,” Estrada said. “Bamboo can become root-bound after several years in planters and will need to be thinned to maintain healthy roots. Another concern is that the roots could be too exposed for cold winters. Bamboo usually does best planted directly in the earth, but can easily be maintained in planters.”
Once you have your bamboo and you have decided how you want to grow it, all that’s left to do is to plant it. Pick a spot in full or part sun depending on the needs of the variety and bury the root ball in a hole about twice its size in slightly wet soil rich in organic matter (though bamboos are tolerant to sandy and clay soils as well).
Caring for bamboo in Maine
Once bamboo is well-established, it requires minimal care.
“Bamboo may require a bit of watering in the first few months and protection from winter in the first couple years, but it is otherwise self-sustaining,” Estrada said. “Bamboo care depends on the species and planting area. It is important to understand that bamboo receives its water primarily through the foliage, so a drip irrigation system is not ideal — hose watering or sprinkler is best. Once bamboo is established after about 3 years, you’ll see it take off in spread, height, and culm diameter.”
There are some ways to protect your bamboo from the cold winters the first few years before the roots are fully established.
“We typically recommend manure and mulch,” Estrada said. “This depends not only on the variety you plant, but also the location [and] planting conditions. We don’t usually burlap bamboo unless in extreme circumstances.”
Thurston said that she doesn’t do anything with her bamboo in the winter.
“It is planted in the ground, and it stays there, and it stays green all winter,” she said.
You may need to do some pruning, though.
“If you wanted to keep it from spreading, late spring, early summer and then late fall you could do root pruning with a spade,” Wallhead said. “The roots can go pretty deep on some of them, so there may be some that escape.”
Wallhead said that he hopes more Mainers will properly and successfully grow bamboo in their gardens.
“I personally really love bamboo,” he said. “I’m interested in seeing more of it being grown properly, but just as with any exotic plant there’s going to be plant management considerations. As long as we’re selecting the right plant for the right spot, we should have a very unique and attractive plant to enjoy.”