One of the most common mistakes made by home microgreens growers is incorrect seed density. Too many seeds and your crop is likely to have a stunted growth or stand a higher chance of disease (such as mould). Too few seeds would result in wastage.
Let me elaborate more in the paragraphs below and then show you what the correct density should be for in the video attached to this blog.
What Is Seed Density?
To put it simply, seed density is the amount of seeds sowed on a tray.
With microgreens, the objective is to grow your crop up to the seed leaf or cotyledon (when the first 2 leaves appear) stage, so the amount of seeds you sow on your tray is very important.
Most information found on the internet today with reference to sowing microgreens seeds is aimed at commercial growers and almost always offers measurements for commercial 10x20” trays. As home growers, we tend to recycle containers (which could come in many sizes) so it is difficult to calculate based on these measurements.
Why Is Sowing The Right Density Important?
In reality, when you throw any amount of microgreens seeds onto a potting mix, your seeds will germinate and grow. But they may not grow uniformly, which is a waste of potting mix and time. Sowing the right amount of seeds ensures that you get the maximum amount of germination and eventually, crop, for your seeds.
Perfect sowing of green pea seeds. This should also apply to seeds like sunflower and wheatgrass
When you sow too little seeds on to your potting mix, you are essentially wasting - you are wasting your time, your potting mix, and potentially your money because low seeding density makes each tray of microgreens more expensive.
On the other hand, sowing too many seeds can also cause problems. The first is stunted growth. Dense planting doesn’t allow each microgreens to get the light they need to thrive and generate energy to produce vitamins and nutrients they are known for. The second problem with dense sowing is the increased chance of fungus or mould growth. This happens because of the lack of air circulation around the plant stems. It provides fungus spores the perfect conditions to develop.
So How Much Should I Sow?
Great question! In the video below, I show you what correct sowing density is for different types of seeds. I have created 4 trays - one for each type of seed. This way, rather than give you measurements, you can get a feel of what the correct sowing density is.
Just remember 2 important points:
1. Each seed has contact with the medium
2. There is some space between each seed to allow for germination. Don't overlap seeds.
With a little practice, I am sure you will get it right. However, if exact measurements is something you are more comfortable with, then this website which calculates microgreens seeding density based on your tray size will be useful to you.