A willow tunnel. Photograph: Anne Green-Armytage/GAP Photos
Every winter, as a ploy to keep my hands busy and my brain from slipping somewhere dark, I craft and weave structures on the allotment. To make traditional structures for plants to climb up (beans, sweet peas and the like), I use hazel or dogwoods. For playful structures that are more sculptural than practical, I love to use living willow.
You can buy willow online (try willowgrowers.co.uk or musgrovewillows.co.uk). It is still relatively cheap. Brown willow is dried and will need to be soaked for several days before you can work with it. Green willow is fresh and won’t need soaking. There are numerous varieties, but white willow (Salix alba) is one of the easiest to get hold of.
It is also possible to get free willow rods. Parks, nature reserves and even car parks use willow for winter interest. S. alba var vitellina ‘Britzensis’, the coral willow, which has bright orange-red young growth in winter, and the golden willow (S. alba var vitellina), with bright yellow-orange new growth, are both widely planted for winter colour. These tend to be cut back hard in late winter/early spring: you may find you can score plenty of pretty rods for no more than a please and thank you.
Willow has amazing properties. One is the ability to root anywhere because it contains salicylic acid and indolebutyric acid in significant quantities. There is an old technique for extracting these rooting hormones by soaking chopped-up willow rods for several days and using the water on cuttings.
Even a considerable willow branch placed into damp soil will most likely root. A healthy rod inserted into the soil will settle down and make a home. This can be exploited to make living willow structures.
Numerous online videos show design ideas. You can make domes, wigwams and forts for small people to play in; these are ideal projects for allotment and community gardens. This winter I am going to create a screen to keep my bees behind. The willow will provide early pollen; it’s cheap and will blend in.
Site your structure somewhere sunny with damp soil (though willow will grow anywhere, it looks sad in dry soils). Avoid buildings, because the roots like to get into drains. Chop off the bottom 10cm of the rod, even if it has rooted, and insert it at least 30cm into the ground to anchor it.
Expect the rod to double in height over the summer. Structural rods planted at a 45-degree angle can be woven in a diamond pattern, which will make for a stronger construction than uprights alone. The stems may naturally graft together when they cross. Encourage this by tying the stems together so they rub. And be warned that both rabbits and deer will like to munch on them.