Bamboo needs a few things to thrive:

Loose, fertile, well drained soil

Over time bamboo will provide its own mulch by dropping leaves which help recycle nutrients and retain water.  Before this happens bamboo should be mulched with compost or other material high in organic matter, a couple of inches will do.  While the canes can tolerate some soil build up around the base try not to bury them more than a couple of inches at most.  One of the best ways to revive a tired old stand is to thin out the older less attractive canes then fertilize and mulch.

Fertilizer should have high nitrogen, the phosphorous and potassium are less critical.  A grass fertilizer works well, but a slow release organic is preferred to synthetics.  Different manufacturers will have many available blends, commonly a mixture of manures, but most any will work well as the bamboo is not particular.  There is no formula for the amount of fertilizer, but generally a liberal amount can be applied especially if using a balanced release rate organic blend.  Apply fertilizer in the early spring before new shoots emerge, and possibly again in mid summer if needed to keep leaves green.  One of the main effects of the nitrogen is to help maintain, or renew a deeper green color to the leaves.  Because most bamboos are dormant in the winter late season fertilizing is not recommended.

Drainage and aeration should be improved by the addition of organic matter, especially when starting with a new planting.  Deep cultivation is not necessary as the root and rhizome system prefers to stay shallow.  Raised beds are a good option to improve the worst drainage problems, and can assist with future rhizome control.  Most Phyllostachys or running bamboos are more tolerant of heavier or less draining soil, though the growth will be limited.  Fargesias, the most common clumping bamboo, are much more sensitive to drainage issues.  Poor draining, heavy soil can stunt or even kill these clumpers.

Summer water

Most of the temperate bamboos grown here in the Northwest originate from China and eastern Asia where the growing season coincides with the rainy season.  We have the opposite, with drought in the summer, and watering is a necessity.  Many older stands seen around town get little to no supplemental water and survive just fine.  But within at least the first two years a newly planted bamboo should be watered regularly.  Usually a deep watering every 3-4 days is best, especially to encourage deeper more resilient roots, but in very hot periods every other day may be necessary.  Drought and water stress can be recognized when the leaves curl.  Some sensitive clumpers will curl their leaves when exposed to hot sun despite being well watered, but most do it as a stress response to reduce transpiration.  There is usually no damage done within the first few hours of leaf curl, and they will open up quickly after being watered.  Bamboo will often reach a stasis point of size relative to its growing conditions and water can help improve the health, or increase the size and growth rate.

Room to grow

The bigger the bamboo, the more space it needs.  Bamboo is an incredibly resilient plant and relatively large canes can grow in small spaces, but it may not last as long or look as healthy as a plant with more room.  Barrier and containers limit the cane diameter and height, and will stress or eventually kill the plant.  Sometimes this can be used strategically to keep a plant shorter, but more care with watering and rhizome maintenance will be needed long term.  For linear screens no less than 2′ width by x length.  For taller timber types 4-6′ diameter of growing space.

If rhizomes can’t spread out laterally, sometimes it can be encouraged to layer vertically.  Old stands naturally self mulch with leaves and over time this gives the plant more growing room as they break down.  Cane thinning and mulching can replicate this, allowing fresh new growth over the top of the old. Clumping bamboos can also need space, they still spread, just more gradually.  Different species will require different amounts of space, but usually clumpers look best with 3-4′ diameter growing area.

Appropriate light

The runners like as much sun as they can get, the clumpers need afternoon shade.  Running bamboo will be shorter with less light, it will also not produce as many or as large sized canes.  Only a couple of the clumping type can exceed their light limits and remain healthy, they are naturally adapted to be understory plants.  With each type, extremes on either end will cause slower growth and less height, this can be used to limit the height when a shorter bamboo is desired.



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