Seed Sowing, Soaking Seeds, and Compost Tea

I like to use compost tea to soak seeds, and to water seeds in when planting, especially in modules. At this time of year the temperature is too low to create a decent compost tea, so how do we achieve the same results?

Soaking Seeds

I pre -germinate all of my larger seeds  by soaking them for up to 12 hours, and  then setting them on damp kitchen paper. That allows me to only use seeds that have shown themselves as viable. This saves empty spaces in pots and modules.

soaking seeds

Pre germinating Soy beans by soaking

I prefer to use actively aerated compost tea in the soak water, to get a healthy bunch of soil microbes coating the seed and root prior to planting out. For smaller seeds I tend to use compost tea to water the seeds initially to achieve the same effect.

compost tea for germination

mustard seedlings germinated using compost tea

For a really  basic explanation take a look at the Compost Tea Link. Alternatively there is a lot of information about compost tea in the archives.

Why Use Compost Tea?

Like many growers, I use a commercially produced potting compost for much of my seed sowing. It’s something that I am reducing, but old habis die hard. I think that these composts are sterilised, probably using heat. If so, that means that as well as reducing pathogens, beneficial soil microbes would be affected too. The compost is bagged up slightly damp, and as it is exposed to the air, it can be colonised by microbes. These are more likely to be harmful than beneficial, leading to the possibility of disease like damping off. My approach aims to get a healthy population of microbes kick started, in order to produce healthy plants and to protect against pathogens.

The Effect of Temperature on Microbes

Cooler temperatures slow down the growth of microbes.That’s how your fridge works. So how do we get a healthy growing population of microbes early and late in the season? Well one approach might be to use a pond/aquarium heater in the Compost Tea brewer. The problem with that is that compost tea is aerated, using an air pump. That means that you are continually pushing cold air from outside of the container into the solution, cooling it down. Of course if you have a heated propagation area, then putting your compost tea brewer in the warm room will raise the temperature, but most people will not have access to that luxury. Many of us do have heated propagators though. Sadly you cannot fit a compost tea brewer into a heated propagator, but that doesn’t mean that we cannot raise beneficial microbes in one.

Compost Tea Simplified.

Making Compost Tea is simply giving a bunch of microbes a food source, allowing them to multiply rapidly. The aeration is there to keep conditions aerobic. This replicates the effect of plant roots secreting sugars from their roots and leaves, to do the same thing. Of course a seed isn’t secreting sugars, and will not do so until it is photosynthesising properly, but if we can replicate that when seed sowing, or seed soaking, we may be able to obtain the same benefits.

The Solution

(No Pun intended). What I do is to get a small quantity of normal compost, and vermicompost. These are the sources of my microbes. The compost is put into bucket, water is added (not chlorinated) and stirred. I then add a small amount of unsulphered molasses, and liquid seaweed.These are the nutrients. The contents of the bucket are filtered, to stop the compost from clogging up my watering cans, and then the liquid is used either for soaking seeds, or watering the smaller seeds. These are put into the propagator, which provides the warmth for the seeds to germinate, and for the microbes to multiply. The microbes use the molasses and seaweed as a food source and multiply in the warm conditions. By the time that the seeds have germinated and started to grow, there should be a healthy population of microbes, and these should help to produce healthy plants. To keep the population of microbes active all that you need to do is to water with a dilute solution of molasses, until the plants are grwoing strongly, at which time they should be managing their own poulations of microbes.
A simple solution.

Wishing you well


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