If you have nettles in your garden don’t dig them all up – make free plant food out of them.B
etter still find another corner and plant some comfrey. Not only is it a very pretty plant but your tomatoes will love you for it.
Nettles are high in nitrogen: the N of the NPK trinity of plant nutrients. Nitrogen is needed for healthy leaf growth so is perfect for feeding herbs, cabbages and lettuces for example that you don’t want to flower or set seed.
Comfrey is high in potassium: K is its symbol on the periodic table. Potassium is needed for flower and fruit formation so use it to feed tomatoes, aubergines, peppers and so on that you do want to flower profusely. Comfrey is a fast growing perennial with very deep roots which tap in to all the soil’s nutrients. Technically it is a weed because once it takes hold it is difficult to remove so choose your comfrey spot wisely.
With both nettles and comfrey you can make a “tea” or liquid feed by stuffing as many of the leaves into a bucket then topping it up with rainwater. Weight it down with a brick then leave it somewhere out of the way until it smells putrid. That’s when it is ready to use! Strain it though a fairly fine garden sieve and then dilute down to about 1:10.
The best time to make both is mid-spring to give both a chance to regenerate and possibly give you another opportunity to make more by late summer. Wear gloves when harvesting the comfrey (and nettles obviously) because the hairs on the leaves and stems can irritate the skin.
If you don’t fancy the stench then you can just put comfrey leaves straight in to the compost heap where it acts as a fabulous conditioner and releases the potassium as it breaks down.
As with all fertiliser use sparingly where needed: over-feeding (as with humans) is as bad as undernourishment!