Seeing double to dig deep ahead of growing your own vegetables

It has been a quiet couple of months for city allotment holder George Sutherland, yet despite poor weather conditions he has managed to complete all the necessary double digging on his plot. Here he shares his top tips with readers.

For growing vegetables, the top eight inches of soil are the most important. So, if you are a new plot holder then this is where to spend your effort. But once that top spit is in good condition, it's time to dig a bit deeper.

Carrots and parsnips like a good depth of rich, open and stone-free soil. This is achieved by double digging. It does take some effort, but can be done in the winter and the results are worth it.

The benefits are a good depth of humus-rich and open soil with good drainage when wet and moisture retention when dry. I try to do a bit, conditions permitting, on every winter visit. That's easier on my back!

My method has been used for generations; only the potato section is double dug. Start by dividing the section length-wise into two equal-width strips. Then, starting furthest from the compost, dig out a trench in the first strip of just over two spade's widths and seven or eight inches deep.

The books will tell you to take out only one spade's width, but it's nearly impossible to pile the soil from the next trench without it falling back into the one that you are digging.

Pile the excavated soil on the nearest bit of empty ground. The aim is to leave about three inches of top soil in the bottom of the trench.

Then, fork over the sub-soil to mix it with this top soil. This is the time to remove stones (I have a handy stone bucket) and the roots of perennial weeds. After years, I still get bits of Mare's Tail.

Now line the bottom of the trench with the compost or manure. This year I've used mushroom compost.

Make the next trench, this time of just over one spade's width, and pile the soil into the first trench, heaping it up furthest from the new trench.

Repeat the process until you come to the end of the first strip and have an open trench.

Now move over to the second strip and take out a double-width trench in the same way as at the start of the first strip. Use the soil to fill the trench at the end of the first strip.

Continue until the whole section has been dug and you have an open trench. Fill this with the soil removed at the start of the process.

After a few cycles of this treatment the sub-soil will be in good condition.

George Sutherland is a past president of The Federation of Edinburgh and District Allotments and Gardens Association (FEDAGA). He has an organic allotment in the Capital and is a five-time holder of the Robin Harper Green Trophy for organic vegetables. For more information visit www.fedaga.org.uk