Experiments with Microgreens
Ferdinand2000
Posts: 537
The next long-term Ferdinandopolis self-education-by-trial-and-error thread.
I have started upgrading my Microgreens area in the conservatory, and had some more lighting for before-Christmas.
The environment is an unheated (electric ufh but switched off) but well insulated conservatory, but with the door to the kitchen open from breakfast time to teatime. Min/max temperatures over the Christmas fortnight have been 20C max, 7C min, with 12-14 in the day and down to 8C more usual overnight.
I am using approx 10-15g of seed per normal seedtray (ie about 20-40p worth from the current supplier), and aiming for a crop 80-100mm high to give me a target yield of 15x to 20x the seed weight. Ideally I am looking for 200g per crop per tray.
The ideal aim is to work up to about 12-15 seed trays, which will one bay of Ikea IVAR 80x50cm shelving at 3 trays per shelf, to give an approximate 100g or 2 x 50g portion of fresh greens each day.
I am using these lights from Roleadro, and the "Red/Blue" mixed version of the same thing. They are mounted to the underside of the shelf above.
https://www.amazon.co.uk/gp/product/B07PG7G71X/
At those temperatures I expect growth to be slightly less than optimal. Eacch light panel is using about 30W of power, which means that the electricity use per 2-light shelf is running at about 1 kWh for a 15-16 hour lighting day, or about £1 per shelf per week (at a guestimated 14.3p per kWh). Or £4 per week on the lecky if I get up to 12 trays.
For everyone who only reads the last paragraph, the ballpark conclusion of all of that is that if I am running 6 trays over 3 shelves on a 3 week cycle ie 6 half-tray portions per week, and getting 150g to 200g harvest per tray, that comes out at something like 75p - £1 per portion. Give or take.
All critique or ideas welcome.
I have started upgrading my Microgreens area in the conservatory, and had some more lighting for before-Christmas.
The environment is an unheated (electric ufh but switched off) but well insulated conservatory, but with the door to the kitchen open from breakfast time to teatime. Min/max temperatures over the Christmas fortnight have been 20C max, 7C min, with 12-14 in the day and down to 8C more usual overnight.
I am using approx 10-15g of seed per normal seedtray (ie about 20-40p worth from the current supplier), and aiming for a crop 80-100mm high to give me a target yield of 15x to 20x the seed weight. Ideally I am looking for 200g per crop per tray.
The ideal aim is to work up to about 12-15 seed trays, which will one bay of Ikea IVAR 80x50cm shelving at 3 trays per shelf, to give an approximate 100g or 2 x 50g portion of fresh greens each day.
I am using these lights from Roleadro, and the "Red/Blue" mixed version of the same thing. They are mounted to the underside of the shelf above.
https://www.amazon.co.uk/gp/product/B07PG7G71X/
At those temperatures I expect growth to be slightly less than optimal. Eacch light panel is using about 30W of power, which means that the electricity use per 2-light shelf is running at about 1 kWh for a 15-16 hour lighting day, or about £1 per shelf per week (at a guestimated 14.3p per kWh). Or £4 per week on the lecky if I get up to 12 trays.
For everyone who only reads the last paragraph, the ballpark conclusion of all of that is that if I am running 6 trays over 3 shelves on a 3 week cycle ie 6 half-tray portions per week, and getting 150g to 200g harvest per tray, that comes out at something like 75p - £1 per portion. Give or take.
All critique or ideas welcome.
“Rivers know this ... we will get there in the end.”
1
Posts
(none of these seeds were soaked overnight, which may have saved a day or two.)
Observation:
This piccie is 2 trays of Red Lentil seeds on day 12.
There is a distinct difference in rate of growth on two trays planted up at exactly the same time. The only thing I can see to cause that is that the shelf below had a light panel mounted on one side and not the other, so the tall one may have had somewhat warmer soil.
That might argue for putting microgreens on shelves above lights, and something less time sensitive eg eventually moving to the garden, on the bottom shelf.
Great questions.
This is my current method:
- Plant seeds on 20-25mm of damp compost in seed tray. Spray with sprayer. Cover with thin layer of compost. Put solid seed tray on top, weighed with brick to ensure seed /compost contact.
- Check and mist daily until 1st green appears. Then remove brick.
- When enough have emerged to lift empty lightweight seed tray by a few mm, turn over and keep covered.
- When there is suitable growth, uncover, put tray underneath and start lights. From then on water from bottom with seaweed fertiliser (at present).
- Harvest when ready or a bit at a time over a week or more as required.
On your Qs
1 - I have yet to decide how "leggy" I want them to be - and it could be the light or it could be that I had them under the inverted seed tray for a day too long. I'll be guided partly by the taste, and also avoiding soil in my salad.
But the 2 trays have been handled absolutely identically, and I spin the whole shelf every few days.
2 - Inclined to agree, but I am experimenting gradually. I think there is also something about germination rate - there are more seeds than that in that tray. And AIUI the cap on seeding density is also to do with how crowded the plants are at harvest, so I need to check harvest weight in similar circs. But I have plenty of seed in 12 variety types to play with.
3 - At present the distance from soil surface to lights is about 22-23cm. That means that the leaves are ending up just below the level at which I feel distinct warmth with my fingers. I'll move them a little closer when I add in an extra shelf, then two.
Do you think I want the leaves in the "warm zone" slightly?
I have been measuring temperatures on that side of the conservatory but not in that particular set of shelves.
4 - It may be coriander. I forgot
Cheers
F
1 and 2 - the same as above (but the other way round after a tray spin). You can see that some seeds are still germinating.
F
(Is it really 2021?)
I planted 2 trays of Red Lentils on 18/12. There is a day 12 photo above, and below is day 18. The bigger tray has 15g of seed. The other 10g. Perhaps due for harvest in a day or two, when I'll know whether I have made my 100g target.
Seeds are still coming through. I wonder if this is to do with a relatively low temperature (approx 10C at times).
After @Skandi's comment, I have tightened up a couple of shelves in my setup. But as I have 2 30x30cm light panels for a 45x75cm area, you can see that this may be too tight due to the shadow in the middle.
These are the light arrangements shown by the purple type
Need to try some tests with shop fluorescents, but the lights are the expensive bit when one has a surfeit of iVAR already. This little lot were over £200 all-in for eight, and these are the budget end for LEDs.
I hope I can be forgiven a Happy Days theme tune, as it has all been so miserable. Have a bop round the kitchen.
F
Attaching the LED lights directly to the underside of the shelves does make the shelf distinctly warm.
I can quite believe it keeps the seed tray soil at a temperature not dissimilar to the 15-20C of a propagator.
Remember that my conservatory hardly ever goes below about 7-8C, even now. And as it faces North it won't over bake either later in the year.
But all the best.
I'm just about to harvest a tray of Red Lentils, and hoping for a second crop. Will see how much it weighs.
Oh yes! Once cut, do they come away again or do you pull them up by the roots?