Trouble Shooting Microgreens Part II
They die, there's mold, there's flies - oh my!
Microgreens are an incredible edition to home grown food. They are fast (compared to most things you grow). They are packed with vitamins, minerals and antioxidants. And they sometimes go very wrong.
Last week, I covered the first two common problems in this list below. You can find that post HERE if you missed Part I:
Problems you see most often with microgreens:
A tray with few plants
Good growth but only in patches and lots of bare soil
Seeds that sprout and then die
Mold
Fungus gnats
Today, let’s finish off this trouble shooting list. And these last three problems can also plague your garden seed starting adventures, so keep these in mind for that gardening task too.
They die, there’s mold, and there’s flies - Oh my!
3. They die - the seeds sprout and then fall over
It is so exciting to see a tray filled with seed come to life. There is a bubbling at the soil the surface as the seed coats emerge and then, almost right before your eyes, you return to find vibrant green sprouts.
That makes the next scene even more devastating - returning to find your tender young sprouts keeled over. Once on their sides, they wither and die fast. Usually by the time you notice something is amiss it’s already too late. The fate of those seedlings (and likely that of the entire tray) is sealed. One falls, and often the rest fall too.
It’s “Damp Off”
Damp off is the term used to describe this very situation - where seedlings start to grow and then die off, usually withering away at the stem near to the ground, falling over in the process. Their stems essentially turn to mush, and/or the seed leaves fail to open, turn brown and die.
Damp off is caused by soil-dwelling pathogens (fungi and mold). These pathogens can be introduced to your microgreens in a variety of ways. Garden soil, dirty tools, your hands and insects can all transmit these pathogens to your microgreen trays.
Once in the microgreen trays, the pathogens spread quickly through the soil when you water. That’s why, when one goes, every vulnerable seedling will likely follow suit.
Damp off prevention
Luckily, there are things you can do for your microgreens (and for seed starting later this spring).
Clean. clean. clean. Make sure that you have clean trays, clean tools and clean hands. Despite how simple growing microgreens is - you are still creating food that you will eat with minimal preparations and that means you should follow food safe practices all along the short journey from seed to table that microgreens offer.
Use sterilized seed starting mix. Damp off pathogens naturally occur in garden soil. Microgreens do best, and are the safest to consume, when a sterilized mix is used. There are soil-less mats that you can buy. I haven’t used those myself since they are more expensive.
Warm them up. Damp off pathogens thrive in cool soil conditions which also put the most stress on your microgreen seedlings. Damp off can be a sign that your microgreen growing conditions are too cold. Add a heat mat, or move your trays to a warmer spot.
Water sparingly. Damp off, as the name implies, happens when the soil conditions are too wet. Poorly draining soil, poorly draining containers, and overwatering all create conditions where damp off thrives. Shoot to water with a mind like Goldie Locks - not too much and not too little - be just right. One solution is to pre-wet your soil mix before you add seeds. That way if you get it too wet, you can delay planting until the mix isn’t too wet. And you can pre-warm the tray before planting if your soil or water is particularly cold.
4. There’s mold!?! Yikes!
Mold is the bane of food production. And that is as true for microgreens as it is for any other food in your kitchen.
Mold can strike at different times in the microgreen story. Seeds may go moldy instead of sprouting. Mold can be a factor in a damp-off story. Mold can affect the roots, stems or leaves of microgreens. And once harvested, your micro-crop can go moldy if not stored properly.
Microgreens should smell (and look) fresh and, well, green (or red if they are beets or red cabbage, etc.). Mold can often be detected by an off-smell that warns you something is wrong.
Mold thrives in cold wet soil conditions. So as with damping off, the above preventions should also reduce the chance of mold in the trays.
Seeds can go moldy for a few reasons. If seeds have been improperly stored, this can lead to them turning moldy in the tray. Essentially seeds that are damaged by heat or moisture may look okay to begin with, but they can’t actually grow and that is why the mold.
Mold prevention
Keeping it clean is the go-to for food production. Use soap, vinegar, and/or hydrogen peroxide (3%) to clean your trays and tools for microgreen production, especially if you’ve had a mold problem.
Make sure your temperature and humidity are maintained. If mold persists, you can try adding a fan for air circulation. But if you followed the suggestions for damp off and you are still getting mold - suspect the soil and/or the seeds as the primary source.
Do not risk eating moldy microgreens. It’s just not worth it. If the mold is isolated to one spot on the tray (e.g. a small group of seeds went moldy), you MIGHT be able to save the rest? But use caution and your best judgement here. When in doubt, I look up food safe recommendations specific to mold and follow those.
5. And what’s with the flies!?!
If you keep houseplants, or grow microgreens or sprouts long enough, sooner or later you encounter tiny black flies that seem to get into everything: Fungus Gnats!
Fungus gnats are completely harmless to people. They don’t bite or sting. But they lay eggs (LOTS of eggs) on organic matter near the soil surface of houseplants or your microgreen trays. Those eggs hatch into tiny larvae that burrow into the soil. These larvae don’t actually harm your plants.
But once you have a population of fungus gnats, you find them everywhere! In your drinks, on your dinner plate, tickling your skin as you watch TV, stuck to windows.
Fungus gnat prevention
Fungus gnats thrive in wet soil, so the best prevention is to allow your houseplants to dry out a little between waterings, and to grow microgreens in well-draining trays.
You can set traps for gnats. They are attracted to yellow sticky traps. And you can set out shallow trays of apple cider vinegar (a small white bowl or plate works well for this).
But one of the fastest solutions to a bad infestation is to mix 1 part water with 1 part 3% hydrogen peroxide and spray the soil of the affected houseplant or microgreen tray. The peroxide will kill the larvae (and even adult flies you hit). But this is a contact-only effect. That means you have to re-spray on a regular basis if you want to get the gnat population under control.
So the verdict here is harmless, but super-annoying if the population explodes.
Microgreens for the win
These 5 common problems with microgreens are actually pretty easy to solve, as you can see. While it may seem like you’ve hit a rut and everything is a mess, the beauty of microgreens is that it is so easy to just pause, clean all your equipment, grab fresh sterile potting soil, new seed, and try again.
The fast turn around time on microgreens means you get to see the benefits of your corrective action on the very next batch you grow.
And your body will thank you for the burst of nutrient-dense food that you can add daily to nearly any meal.
Pro-Tip for Microgreens
Sometimes microgreens grow so fast and so lush that you just cannot eat them all. Hate to waste microgreens that are a bit too big to still be tasty?
I discovered that if I harvest the “overdue” microgreens, rinse them clean, and then load them in my dehydrator, I can make my own super-green powder for adding to smoothies or meals. I use the tray liners for my dehydrator to keep the fine materials in place.
Of course microgreens shrink down to almost nothing (except the big ones like peas and sunflowers). But I just dry the leftovers and add them to a clean canning jar with a good fitting lid. Once I have accumulated enough material, then it is easy to process it into a powder using a blender or food processor.
You can also just grab dried greens from the jar and crumble them into whatever you are making.
I also feed the stubble to my chickens as a treat. I just toss the whole thing in - soil and microgreen stubble - and the chickens do the rest. But you could also toss these remnants into a compost pile, or use it as a top-dressing out in the garden somewhere.
Happy growing!
S
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In the coming weeks, here at The Naturalized Human, we are going to explore:
How each of your senses (Touch, Taste, Smell) contribute to your microbiome
Options for getting that dose of nature inside your own home, when it’s too cold be outside for long
Whether our pets are contributing to our health, or if they are simply mirrors of our inadequate environments and lifestyles
AND - Keep an eye out for some how-to videos that I am working on (for paid subscribers) - I am looking forward to adding some more resources like these to this newsletter in the coming months.
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