Comfrey - Tea, Bees, Butterflies and Plant Thuggery.

As a trying-to-be-self-sufficient gardener I make my own fertiliser from both wild plants growing of their own volition on the plot and from plants that I've introduced. Nettles fit the first criteria - any gardener should try to have a nettle patch in a tucked away corner, behind the shed or at the back of the garage perhaps, because it is an important food plant for the caterpillars of butterflies such as small tortoiseshell, peacock, red admiral and the comma, one of my favourites. 

It is pretty straightforward to make a quick release liquid fertiliser by steeping nettle leaves in water, having checked for caterpillars before picking the leaves, of course. The leaves are high in potassium and nitrogen, essential for growth and flowering.

Comfrey, however is higher in potassium than nettles and once you have an established clump is quick and easy to turn into fertiliser. Be very wary of the term established clump, because unless you use the recommended sterile bocking 14 variety you may well end up with established clumps all over the place. 

I rashly bought seed rather than sterile plants, working on the principle that as we have a pretty big plot letting the beast self-seed all over the place wouldn't be a problem. I then planted my new little plants at one end of my asparagus bed! This was a very, very bad idea as weeding an asparagus bed is difficult enough, but comfrey seems able to put down a huge woody tap root within seconds of germinating and I am beginning to lose the battle. It is also appearing elsewhere in the potager and completely resists being dug out.


However,  bees and other pollinators adore the purple flowers so I just have to be incredibly vigilant and remove the flowers as soon as they even think about setting seed. I'm debating allowing a clump to establish in one of the wilder parts of the garden but don't want to be responsible for letting a thug escape into the wider landscape!

There is plenty to be read online about making comfrey 'tea'  or liquid feed, especially about the nutritional values so please don't take my methodology as the only way forward - this works for me. For preference I use a lidded bucket simply because the mixture stinks when ready. You can also cover the bucket with an old compost sack.

Fill the bucket to just below the top with freshly harvested leaves packing them down gently and fill with water to the top. I leave the lid off for twenty-four hours to allow any creatures to escape that I may have inadvertently caught on the leaves. 

Cover and leave in a shady place for about ten days to a fortnight until the leaves have broken down to a stinky dark mush. 

 To filter the liquid fertiliser from the sediment I place a riddle covered with an old scrap of net curtain over a bucket and very slowly and carefully pour out the contents.

Carefully because you don't want to be splashed, unless you fancy spending half an hour in the shower scrubbing that is! The stink really clings. I then decant the liquid fertiliser into large plastic bottles ready for use and dump the mush on the compost heap. 






The fertiliser needs to be diluted for use - about 10 or 12 parts to one is recommended - although I tend to just add a very nontechnical slosh into the watering can. Ideally the resulting water needs to be a pale yellow colour: too dark and it may be too strong.  

Potassium is needed to help plants flower and set fruit so it is once the plants are established that it comes into its own. From early June I begin a once weekly ritual of liquid feeding most vegetables in the potager plus my pots and tubs of flowers. The nitrogen element will also promote growth in the plants not yet flowering, or not grown for flowers or fruit like cabbages.

A bucketful is not enough for what I need so I begin making fertiliser from late April or May and store it in the shed out of sunlight. There are suggestions that the fertiliser loses potency once made so I don't keep it hanging around more than a few weeks.

Some people advocate hanging an old pillowcase full of leaves in your water butt; this wouldn't work for me because during heavy rain or storms (frequent in the summer) the water flushes right through the butt system, but it might be a way of avoiding the stinky splash back problem!

Happy Gardening.