Nettles, comfrey or horsetail left to steep in a pail of water turn, through yeast-driven fermentation, into a dark liquid that both feeds plants and stiffens their defences. Spray before trouble arrives rather than after: these home-made teas cannot cure a disease already present, but they help plants shrug off mildew, rust and aphids.
Each often doubles as a very nourishing fertilizer. Each weed or plant has compounds that produce different results.
These are the main fermented teas and decoctions for:
This is one of the most common, since it serves to fight pests and can also be used to fertilize soil thanks to its high organic matter content.
Discover the technique on how to prepare fermented stinging nettle tea.
Cut your nettles before they set seed, or you risk sowing them all over the garden.
Strain the liquid through cloth before it goes into a sprayer, and toss the leftover pulp on the compost heap.
Each weed or plant brings its own compounds to the pail, so the brew you make depends on whether you are aiming at a pest, a fungus, or plain growth. Here are the main fermented teas and decoctions side by side.
| Tea or decoction | Main use | Acts against |
|---|---|---|
| Fermented stinging nettle tea | Disease prevention plus soil feeding | Downy mildew, powdery mildew, rust; repels aphids |
| Fermented rhubarb tea | Quick pest spray, ready within 24 hours | Allium leaf-mining flies; repels aphids |
| Garlic decoction | Stopping fungus spreading in the vegetable patch | Downy mildew, European brown rot, rust, peach leaf curl; aphids, thrips, mites and ticks |
| Fermented comfrey tea | Growth booster, used when watering | Not a treatment: supplies potassium and nitrogen |
| Fermented horsetail tea | Fungal defence, especially on fruit trees | Downy mildew, European brown rot, rust, peach leaf curl |
Whichever you choose, these brews work by strengthening the plant beforehand, not by rescuing it afterwards.
The advantage of this fermented tea is that it is ready to use within 24 hours.
Here is the technique to prepare fermented rhubarb tea.
This is an excellent way to fight the spread of most fungus, especially in the vegetable patch.
Here are the steps to prepare a garlic decoction.
Renew the spray after heavy rain, since rainfall can wash much of any foliar preparation off the leaves, and reapplication after downpours is standard practice for such home-made plant sprays.
This is possibly the fermented tea that most organic farmers use. Comfrey indeed contains very high levels of both potassium and nitrogen, which boosts plant growth for all plants in the vegetable patch.
Here is the process to prepare fermented comfrey tea.
This tea is a powerful defense against fungus-related diseases, especially on fruit trees.
Here is the process to prepare fermented horsetail tea.
Weed tea goes through a process that other fertilizers don’t: fermentation. In a nutshell, yeasts break the plant material down very effectively – and they add their own products to the mix, too!
Weed tea thus doesn’t only rely on the special nutrients and compounds of the plant itself. It also pack in the work and nutrients of yeast as it does its work fermenting.
Which weeds grow in your area that you use to make fermented tea?
Comment below if a local weed is a true hassle for you – there are chances it’ll make an excellent weed tea!
Combine weeds to multiply their benefits. Feel free to add whatever you have at hand to the pot!
