It is hard to get one’s mind around the idea of drought tolerant bamboos. I suppose like most gardeners I have been influenced by two main myths about bamboos: 1. they run like crazy and are invasive 2. they like a lot of water. Like most myths there is a grain of truth somewhere in these statements, for bamboo is a term for over 1,400 species of grass in the Poacae family with some members coming from very tropical regions. These latter can grow very fast, may run and need a lot of water.
The ones that we are talking about are much more restrained, although they are big plants of course, trying to shoehorn any of them into a small garden would be madness unless you are after a dense jungle look or need a thick screen. This Phyllostachys aurea, left, is a typical size, about 3m h x 1m w. Our gardens have become so full of plants that have been bred to be dwarf; bamboos are simply not like that and bamboos have been mis sold to many people who simply should not have them in their gardens. Bamboo nevertheless is the quickest and best way to screen off ugly areas even in a summer dry garden. I have used bamboo to block off adjacent fencing and low buildings with great success. It looks green and lush and calming, so Zen-like. I love the way their leaves dance, fluttering in the slightest air current.
Bamboos are always expensive to buy, but to me they are great value for money as they give you a result in 2-3 seasons. They also happen to be wind tolerant too.
Phyllostachys aureosulcata ‘spectabilis’, left, is the only one of this list that runs much – depends on your soil; rock hard dry clay is not conducive to it running much at all. However, given the chance it will definitely do so. The runners can be cut off and dug out to be transplanted somewhere else, cut the culm right down to the ground. You will need a very strong pair of secateurs or a fret saw to cut through that running root. New shoots on the runners will abort in spring if the plant is on the dry side. Pseudosassa japonica tends to spread a bit, producing a single leader that runs up to 5m or so, more over time.
All the others are more clumping in nature, but do give them plenty of space, the clumps themselves can get quite large (2m x 2m or so in time). All will grow in full sun to light shade – if protected from the heat of the afternoon sun they will stand more drought.
So what about drought tolerance then? Well, in the right conditions all of these can definitely survive without any summer water at all once they are established. I have seen plenty of bamboos in these conditions, they may lose their leaves, partly or completely if very dry, but these will regrow after it has rained. Of course growth will be quite slow with the plant under these stressed conditions and I give mine a really good soak once a month. (The first sign that a bamboo needs more water is that the leaf tips go brown; here that is just a fact of life.)
The other key to maximum drought tolerance is soil preparation when planting. Bamboo is one of those plants that will reward your efforts at planting admirably and punish you for your laziness. The same bamboos planted in thin poor soil will grow to 1/3 of the size of those planted in a properly prepared site and they will suffer stress unless watered frequently.
Planting bamboo is an admirable way to burn off a 1,000 calories! If you have a very hard clay and several plants you really need to hire a mini-digger to do it. Think of it as if you are preparing a deep pocket into which the clump will grow. Prepare a hole about 1m across and dig down to 3 or even 4 spade depths, using a pick axe to loosen the soil and a spade to remove it. Pile each spade depth of soil up separately, remove the bottom spit and spread it in a spare corner of the garden. Add an spit depth of well rotted compost or even better 50% compost 50% rotted horse manure, work 1/3 into the bottom of the pit, breaking it up as much as possible and then work the rest of the compost into the soil as you plant the bamboo. 3 handfuls of blood fish and bone will help the plant settle in.
Water in thoroughly and mulch it thickly with rotted compost or shreddings, or even better use it as part of a planting with semipermeable membrane and a top layer of gravel. If you do this latter, watering will be minimal after establishment. Regarding establishment, I would water weekly for the first year in summer, if winter rain fall has been light monthly in winter/autumn/spring. In the second year drop the summer watering to twice weekly.
As for feeding, if water was unlimited then I would give bamboos a good dose of nitrogenous food on a regular basis , but in dry conditions, I simply give them a 2 handfuls each of blood, fish and bone in spring, not wanting to push them into a lush growth that will only get scorched later.
Bamboos need very little care, which is certainly a great attraction – simply cut out any weak canes. You can also remove the bottom leaves and side stems to show off the attractive colouration of the stems. If the canes get too tall, you can cut the tops off, but of course that cane will not regrow. Pseudosassa japonica, left.
I feel certain that there are many other bamboos that succed in drought conditions (Dendrocalmus strictus is reputedly very drought tolerant, indeed I have seen it growing in very dry conditions in Morocco, but it is of questionable hardiness here and only obtainable as seed)
These bamboos associate well with other tropical looking plants; Miscanthus sinensis, Riccinus and Phormium tenax, none of which need much water.