You can also make your own liquid fertilizer from nettles or comfrey. I like the idea of plants absorbing the typical garden mix of nutrients and passing them back to other plants that also grow in the same soil.
Nettles are a great source of nitrogen, especially at the beginning of the season. Simply fill a bucket, add water, and let it sit. After a few weeks, strain the liquid, dilute it (1 part nettle manure to 20 parts water), and fertilize weekly.
This is especially good for plants like chilies and tomatoes and stimulates them to grow vigorously before flowering.
The best all-purpose fertilizer, however, can be made from comfrey. This plant sends taproots up to 3 meters long deep into the soil and is exceptionally good at absorbing nutrients and storing them in its leaves. These decompose very quickly, allowing the nutrients to find their way back into the soil exceptionally quickly.
Comfrey leaves also have the highest protein content of any vegetable.
20 years ago I planted a whole row of comfrey as fertilizer
They originate from a nearby riverbank, where they had sown themselves with other plants next to a polytunnel. Today, they stand under the high hornbeam hedge that protects the vegetable garden from northerly winds. There, they continue to grow vigorously and are regularly harvested.
More nests have spread throughout the garden. They're not only a great addition to the compost heap, but also an excellent food source for bees.
If you cut comfrey back to the base each time, you can achieve three to five “harvests” per year.
To make my comfrey manure, I fill a bucket with leaves and then with water. The mixture quickly turns into a horribly smelly broth. The stench indicates that the proteins—comfrey contains up to 3.5 percent of them—are decomposing.
After two to three weeks you have a finished, greenish-brown liquid fertilizer.
A mixture of 1 part manure to 10 parts water is just right – but if it's a rich, dark brown color, 1:20 will also work. You don't need a measuring cup – just eyeball it. A higher concentration won't produce better results.
The solution can be sprayed directly onto the foliage as a foliar fertilizer or used to water the root area.
Nettle and comfrey manure will keep for a year in a sealed container, but we use it much faster. The results aren't spectacular, but they don't have to be. It's simply about providing plants in a greenhouse or pot with the nutrients that nettles and comfrey have extracted from the soil and stored in their leaves. It's all about balance. As always in the garden.
