Very fast growing willow varieties ( “Super Willows” ) are the fastest growing & highest yielding tree or shrub in Britain. Planted from scratch, they will produce more wood (or energy) per sq metre (or per acre) per year, than any other tree or shrub in our climate. They are so fast growing you can harvest your first crop of firewood in as little as 5/6 years from planting. Each willow copse can be harvested every five years multiple times for at least a quarter of a century or longer.

This will depend on many factors such as size and insulation quality of your building, the ambient outside temperature, stove efficiency and your own preferences. Energy use is often measured in Kwh (Killowatt Hours). Your Heating Bill will show how many Kwh (units) you use.

1,000 Ltrs of Heating Oil provides approximately 10,000 Kwh.
1,000 Ltrs of LPG provides approximately 6,500 Kwh.
A Tonne of Air Dried Willow provides approximately 4,000 Kwh

Ofgem’s current figure for average heat energy used by a 3 bedroom house in the UK is 12,000 kWh a year (e.g. 3 Tonnes of Air Dried Willow)

Ofgem’s Typical Domestic Consumption Values – TDCV’s – can be seen here: https://www.ukpower.co.uk/home_energy/average-household-gas-and-electricity-usage

To make things simpler we refer to a 10m x 10m plot of land planted with Willow as “a Copse” To grow 1 Tonne of seasoned wood every year you will require 500 sq m.
(approx 2 tennis courts) e.g. 5 Copses, harvesting one copse each year. To grow 2 Tonnes of seasoned wood every year you will require 1,000 sq m.
(approx 1/4 of an acre) e.g. 10 Copses, harvesting two copses each year. In other words, not nearly as much as most people think; making it possible for smallholders and even many suburban dwellers, to grow at least some of their own sustainable firewood.

“Super Willows” grown for firewood are not only very fast growing & high yielding but are also very tough and adaptable to a wide range of soil types and growing conditions. They are generally more tolerant of conditions than other tree or shrub species and they will grow in exposed situations at high altitudes and even by the sea. Full sun is desirable, partial shade is acceptable, but heavily shaded sites, such as beneath the canopy of larger trees are not suitable. Good weed control is usually the most important factor for successful establishment and rapid growth in the first season.

Coppicing is cutting a tree/shrub right down to ground level to harvest the wood & stimulate regrowth. Not all trees/shrubs can be coppiced but willow is the coppice species par excellence, reliably re-growing from the roots each time. Regular coppicing also stimulates more vigorous re-growth & extends life span ensuring higher yields over longer periods. Because of this a coppiced tree/shrub produces more additional wood per year than one that is not coppiced. (It is a little bit like the gardener’s practice of dead-heading flowers to stimulate the parent plant to keep producing more flowers) Pollarding is the same process except it is harvested above ground level. In effect you leave a trunk or pole (pollard) with a crown on top to raise the height of tasty young regrowth above the reach of grazing animals. It can also raise the harvesting height for the convenience of the harvester.

Most grazing animals will readily eat willow so need to be excluded from the copse particularly when the willow is young and tasty. Rabbits need not be excluded from the copse if you are using the Pollard method and you protect each willow plant with a 2ft tree spiral until the bark of the trunk is too tough to be palatable. As an alternative to firewood you can of course grow willow as a feed crop for your grazing/browsing animals.

Five year old coppiced willow stems may be up to 3 or 4inches thick. As such they can be air dried to about 20% moisture content, required for efficient burning, in less than 12 months. The best method is to cut into cordwood lengths (about 6ft) and stack off the ground with one end facing the prevailing wind. After several months you can cover the top of the wood pile with a sheet of corrugated tin or similar. This will prevent further wetting but still allow air & sunlight to circulate helping to thoroughly dry the willow making it ready for efficient burning.

When oil, coal or gas are burned you are releasing thousands or millions of years worth of concentrated carbon accumulation back into the atmosphere. By contrast when you burn 5 year old willow wood you are only releasing the previous 5 years worth of carbon accumulation back into the atmosphere. Hence willow is considered to be carbon neutral and does not significantly contribute to global warming as the use of fossil fuels does.

There are many benefits to the Environment when you grow willow for firewood: Because of Willow’s fast growing nature, large amounts of leaf litter are produced, increasing the humus content of the soil, benefitting soil micro organisms and building biodiversity from the ground up. Above ground, the number of insect species that Willow supports is equivalent to the native Oak. Amongst the other benefits of such biodiversity, these insects provide a valuable food source for birds and other animals higher up the food chain. Early flowering catkins are especially useful for bees and other insects in early spring when there is little else available. One of the many reasons willow was traditionally grown close to orchards and market gardens is the knock-on benefit of providing habitat for populations of pollinating insects.