Your Microgreen Growing Checklist
You’ve followed all the instructions and watched the videos on repeat, but STILL, your microgreens aren’t growing as expected.
Before you throw in the towel, (or the microgreen tray), use this checklist to see if you can spot these potential issues to avoid them happening with your next batch.
- You’re using fresh, potting soil
- Your tray isn’t overfilled with seeds…
- And spread evenly across your growing medium
- You did the ‘blackout period’ to germinate
- Your microgreens are in a well ventilated space with natural light...
- But kept out of direct sunlight
- You rotated your tray so your greens grow evenly
- You haven’t over-watered
- But haven't under-watered either!
- Your microgreen are sitting their own spot indoors, away from other indoor plants
You’re using fresh, potting soil
Let’s start with the first step; the growing medium you use is the first important element to successfully growing your microgreens. You may prefer to grow your greens hydroponically, but if you’re using soil, it should be fresh soil that is specifically prepared for potted planting.
Although it might be tempting, most recommend not reusing the soil you’ve already grown your microgreens. However, another school of thought argues it is ok to reuse soil using the underside roots as a sort of compostable base, transforming it into a sustainable material, as explained here in this GARDENISTA.
There’s also a great podcast – The Microgreens Podcast Episode 009, in which host Todd Marsh talks about this subject that’s worth a listen if you want to find out more.
But, most micro-growers avoid this because of the risk of damping-off disease and bacterial growth such as E-coli, and the second reason is pests.
Common garden pests such as Aphids can infest your microgreens, especially if situated near other indoor plants (more on this later) or grown for specific periods.
Lastly, the goodness and nutrients in your previously fresh soil reduce as you use it. This can be avoided by composting and blending it with new soil, then it can be used maybe one or two more times, but this is quite a time and effort-consuming.
Therefore, if you are starting your microgreen growing journey, we suggest sticking to the fresh batches of soil until you have gained a little more experience and have time to experiment with different methods.
Your tray isn’t overfilled with seeds… and they're spread evenly across your growing medium
You’re not alone in thinking the more seeds you use, the more microgreens you can harvest, but overloading your trays can hinder their growth in various ways.
Adding too many seeds to your tray will cause them to fight against each other for the soil’s nutrients, water, sunlight and air. Overcrowding can also cause your greens to wilt and even produce mould.
If you want a healthy, nutrient-rich tray of microgreens, sprinkle your seeds evenly over your growing material, allowing enough space between them to get an equal amount of goodness (and avoid fisticuffs). This also helps to prevent your greens from growing unevenly.
You did the ‘blackout period’ to germinate
The blackout period is an essential part of the growing process for your microgreens. Once your seeds are sown, place them in a dark space to germinate. This process really accelerates their growth.
During the cold months (this is about 11 out of 12 here in the UK), I cover and place them in a cupboard in a warm but not humid room; place a lid on top that covers my pot, tray or planter completely, and leave for 48 to 72 hours, or whenever I start to see shoots appear.
Some growers place a weight on top of the lid during this period. The weight pushes the seeds into the growing medium, and instead of crushing them, encourages growth, lifting the weight. However, this method is not always recommended; it depends on what type of microgreen you are growing; in most cases, just a cover will do.
You do not need water during the blackout period because the soil should be moist enough to germinate the seeds.
The greens may look a little yellowish when you take them out of the blackout period. This is perfectly normal because the microgreens haven’t been through photosynthesis yet (exposure to light), but once they are moved into natural light, they will turn green.
Your microgreens are in a well ventilated space with natural light… but kept out of direct sunlight
So you’ve completed the blackout period and have now moved your microgreens into the light.
They will grow best in natural light and in an area that is well ventilated. If you place microgreens in direct sunlight, this can cause several issues, including mould, which loves a humid environment caused by the combination of too much heat and overwatering (more on this later).
Again, direct exposure to the sun can cause your greens to wilt, so keeping your microgreens on or near a window ledge that is preferably north-facing should do the trick. If that’s not possible in your home, you could use a growing light as an alternative. The Spruce recently reviewed the best grow lights for US growers, and there is a UK equivalent here.
You rotated your tray so your greens grow evenly
I mentioned earlier that one way to ensure your greens grow evenly is to spread them evenly (go figure!), but other factors can impact their growth rate. I recently experienced this when experimenting with growing Red Garnet outside in trays. I hold my hands up and admit I was guilty of over-seeding (never divert from the checklist!)
And my trays were placed on a shelf in a partially shaded area, but as the days progressed, parts of the tray were exposed to more light than the other and grew in patches, with some growing taller than others and some seeds not germinating at all.
After moving the tray, growth improved, and as I saw the greens growing towards the sunlight, I rotated the tray to ensure the light exposure evened out, but they hadn’t reached the level of growth I would have hoped for, but t was an excellent in-action lesson for me!
You haven’t over-watered
As discussed, when your microgreens initially come out of the blackout period, they will have a yellow hue, but if they have been in natural light for a while and are still yellow, this could be a sign of overwatering.
When you first prepare your soil, in this case, I will use our coco coir discs as an example; they have absorbed water and expanded and should have retained enough moisture to germinate. Once they are in the light, it is tempting to overcompensate on the watering front, but as a general rule of thumb, watering one or two times a day should do the job. I usually water first thing in the morning and then later in the evening, but if the soil looks or feels dry to touch, mist or sprinkle with water.
You can also try bottom watering by placing a drainage tray or pot inside another tray with 1 to 2 centimetres of water and often checking to see if the water has been absorbed – you don’t want your microgreens sitting in stagnant water.
Some prefer this method as the top soil being too damp can again cause mould, which is why the ventilation part (including drainage) of your growing process is crucial.
The trays we provide in our kits currently don’t have drainage holes (excluding the ceramic pot kits). This is because soil acts as natural drainage and the roots of microgreens are relatively short, so we recommend filling your tray about 4 or 5 cm deep with your moistened soil to allow for the natural draining process to occur.
*If you think you spot mould, make sure you’re not mistaking it for root hairs, know how to tell the difference?
The first thing you might detect is an unpleasant smell; this is a sign of mould. Mould looks like clustered, white mounds or spider webs appearing on your growing medium and sometimes leaves, whereas root hair will be fuzzy white hairs of the stem roots.
Ways to avoid mould, as well as the ones already mentioned in this article, is to
- Use high-quality seeds – we use certified organic seeds that are not treated with any chemicals
- Soak and rinse your seeds, although not all microgreens require pre-soaking.
- Make sure your growing trays and pots have been clean and sanitised
If you already have mould…
- Do a check of your tray, removing any affected greens completely
- Delicately clean your crop if the mould has spread to the leaves
- If like me, you are growing for personal use and see small clumps of mould on the soil, you can remove the affected soil with a spoon and cut higher up the stems when you harvest the crop, then, of course, thoroughly wash. But this is entirely a personal choice, if you don’t feel comfortable, don’t use them, and this shouldn’t be done if the purpose of growing is to sell them.
- Some use a hydrogen peroxide spray mixed with water to spray their greens as it’s a natural pesticide but can leave a faint taste that can be removed with washing, as explained in this SFGATE article. I like to use a Grapefruit Seed Extract concentrate by adding ten drops to a spray bottle (minimum 150 ml of water). It’s 100% natural and doesn’t contain any chemicals, alcohol or solvents
- If the mould is too widespread, you may have to throw it away and start again. It’s annoying, but it’s not worth keeping a tray of unhealthy, potentially harmful greens
But haven't under-watered either!
I know, I know, it feels like a bit of a balancing act, but as long as your soil is not sopping wet and you’ve followed the previous step, you should be ok.
As with checking that the soil hasn’t been over-watered, look at and touch the soil to check that it has moisture and isn’t dry.
Your microgreen is sitting in a spot away from other indoor plants
This might sound like a bit of a strange one, but the main reason for this is those pesky pests again. As mentioned earlier in the article, common garden pests may be attracted by your other indoor plants. If your microgreens are sitting in the same area, close to your other indoor plants, the pests will add your microgreens to their buffet, so to avoid this, have a special spot just for your greens.
Although it is a rarity for microgreens pests, especially if grown indoors away from other indoor plants, you can check the undersides of the leaves to ensure there are no tell-tell signs of these unwelcomed tiny visitors such as leaf curling or sticky substances. Garden Focused and the RHS website give the lowdown on Aphids and how you might avoid them.
When growing outside, which I mentioned earlier, is rare, I cover with a garden mesh for added protection.
Sources
- https://www.gardenfocused.co.uk/fruitarticles/pest-disease/aphids.php
- https://www.rhs.org.uk/
- https://homemicrogreens.com/reusing-microgreen-soil/
- https://www.gardenista.com/posts/ask-the-expert-9-tips-to-grow-edible-microgreens/
- https://www.thespruce.com/best-grow-lights-4158720
- https://www.bestproductsreviews.co.uk/grow-light-for-indoor-plants
- https://homeguides.sfgate.com/drought-tolerant-plants-outdoor-13771625.html
Leave a Reply
You must be logged in to post a comment.