compost Compost tea is traditional compost steeped in water, to create an extract for use as a soil drench or foliar feed. Farmers have used compost tea for generations as a cheap and effective means of adding nutrients to plants; however, the cannabis community only woke up to compost tea’s potential within the last decade or so.
Now, countless products are commercially available, so that you can mix your own compost tea in minutes from a packet if desired. However, making your own compost tea is a fun and rewarding way to learn more about organic plant nutrients, and in the long run will prove much cheaper than buying in expensive pre-mixed products.
But why should I make compost tea for my cannabis plants?
Pretty much every grower of any plant will be aware that adding compost to soil can enrich it greatly. Growers of organic cannabis that mix their own soil make use of compost or its constituents (such as humus or worm castings) as soil additives, and commercial soil mixes usually contain a good proportion of the same.
The basic premises underlying the enrichment of soil with compost are provision of micro- and macro-nutrients to your soil; improved drainage, aeration and texture of soil; and (last but certainly not least) development of the so-called ‘soil food web’—the fungi, bacteria and other beneficial microorganisms that naturally live in soil—which form symbiotic relationships with your plants and can seriously improve their overall health and yield.
Compost tea should never be a total replacement for traditional soil additives, but can be a excellent means of complementing and adding to your ‘soil food web’ when used as a soil drench. Compost tea also contains abundant micronutrients that can be absorbed through the stomata of the leaves when used as a foliar spray.
So what do I need to do?
You will need:
- 10 litres of good-quality, well-aerated organic compost, either pre-bought or home-made (home-made is considerably cheaper. If making your own compost ensure that it is fully mature before use)
- a 20 litre bucket
- an aquarium pump with 2 or 3 airstones or bubblers
- 250 ml of unsulphured organic molasses
- 10 litres of water
- a long pole or stick for stirring
- muslin, cheesecloth or a similar natural textile to strain the mixture
- fill the 20l bucket with the 10l of compost and top up with the 10l of water
- add the 250ml of molasses (you may need more in cold weather, as the microorganisms will require more energy to reproduce)
- stir the mixture thoroughly, making sure to thoroughly mix up the solids at the bottom
- place the aquarium pump inside the bucket and switch on, to provide aeration
- leave to steep for 2-3 days, stirring at least three times per day
After 2-3 days, check the aroma of your compost tea brew. If it smells unpleasant or fermented, add a little more molasses, stir, and leave for another day before checking again. You should never need to leave your mixture to steep for longer than 3 or 4 days.
When it has achieved a pleasant, light, musty aroma, it is ready to be strained through the muslin or cheesecloth and used. Your compost tea should always be used within the first few hours after being decanted; if this is impossible, add a little more molasses and switch the pump back on, so that the bacteria is provided with oxygen and nourishment. This way, you can extend its life for a few days—but never leave it for any longer than that!