MIKE I’ANSON, of Helmsley Walled Garden, is getting down to earth making fertiliser.

The gardening season is now fully upon us and our plants are growing, those we have sown, as well as the weeds. The lighter evenings give us more opportunities to keep ahead of demand, but usually our enthusiasm to do it all has to be tempered with a compromise. Yet every year I experiment not just with seeds and plants, but with gardening practises.

One you might wish to try yourselves is producing your own liquid fertiliser from plants. One well-known plant for this is comfrey. It is a vigorous plant and I have found you can harvest the leaves up to four times a year. Cut the leaves down after they have flowered and before they set seed.

The down side to comfrey is it can be invasive and if it sets seed will certainly pop up all over your garden. The other downside to comfrey is you need to allocate a fair amount of space in your garden to grow it and this may be too much of a sacrifice for the small garden or allotment holder.

The alternative is the humble nettle, which you can collect from hedgerows, parks or waste ground; some gardeners even allow them to grow in their own garden.

Cut the nettles down and bruise them; you could run them through a grass cutter. Place in a large bin or bucket and compact with a weight – this can be a compost bag with soil in or a brick or stone. Then, cover with water and leave for a few days, probably no more than four, if you have the time you can stir the mix. Once you start to notice the smell getting stronger, it is time to remove the weight and drain the liquid through a garden sieve or old colander.

If allowed to continue to rot, the decaying nettles form unwanted bacteria due to being kept in anaerobic conditions (they are underwater). You will not know how strong your mixture is and the best rule of thumb is to dilute it until it has the appearance of tea. This can then be applied to your plants, but make sure to water the roots not the leaves to ensure no unwanted leaf burning takes place.

For my experiment I took two grow bags and planted the same cultivar of tomato in each bag. Throughout the season I fed one bag with comfrey water and one with a commercial tomato feed.

What I found was that to keep the tomatoes growing strongly I had to feed with the commercial feed once a week, but with comfrey I had to feed at every watering to maintain the same growth rate.

I also found that the tomato plants fed with the organic tea had a more earthy taste to them.

Whether you have the time to produce your own fertiliser or have chosen to buy one will be one of the many compromises of time we will all have to make throughout this coming growing season.