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Experiments with Microgreens

Ferdinand2000Ferdinand2000 Posts: 537
edited January 2021 in Fruit & veg
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.

“Rivers know this ... we will get there in the end.”
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  • Ferdinand2000Ferdinand2000 Posts: 537
    edited January 2021
    Initial Planting Diary

    (none of these seeds were soaked overnight, which may have saved a day or two.)

    18/12/20 Red lentil 10g
    18/12/20 Red lentil 15g


    28/12/20 Radish Vulcano 15g
    28/12/20 Red Kale 9g
    28/12/20 White Mustard 10g

    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.

    “Rivers know this ... we will get there in the end.”
  • SkandiSkandi Northern DenmarkPosts: 1,577
    edited January 2021
    Couple of comments;
    They are not getting enough light you need to lower the lights or raise the trays, all of those plants are stretching badly for the light.

    I think you can double or even triple your seeding rate with those lentils, which would save space and electric

    Did you check the temperature with the lights on? LED's don't produce as much as a tube but they do still produce some. on a bright day (when it was 20 before) you may be getting very warm.

    I don't grow microgreens  but I do grow many thousands of seedlings each year under lights. I keep the lights close less than 6cm away from the seedlings, but even so some plants like more light than others, it's interesting the tray on the far right (coriander?) looks like it is getting enough light but those lentils do not.
  • Ferdinand2000Ferdinand2000 Posts: 537
    edited January 2021
    (The title of this thread is inspired by the wonderful "Experiments with Mice" by Johny Dankworth a few years ago.)

    https://www.youtube.com/watch?v=onET849hgbc
    “Rivers know this ... we will get there in the end.”
  • Ferdinand2000Ferdinand2000 Posts: 537
    edited January 2021
    @Skandi

    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
    Skandi said:
    Couple of comments;
    1 - They are not getting enough light you need to lower the lights or raise the trays, all of those plants are stretching badly for the light.

    2 - I think you can double or even triple your seeding rate with those lentils, which would save space and electric

    3 - Did you check the temperature with the lights on? LED's don't produce as much as a tube but they do still produce some. on a bright day (when it was 20 before) you may be getting very warm.

    4 - I don't grow microgreens  but I do grow many thousands of seedlings each year under lights. I keep the lights close less than 6cm away from the seedlings, but even so some plants like more light than others, it's interesting the tray on the far right (coriander?) looks like it is getting enough light but those lentils do not.

    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  B) . But again - I am spinning the whole shelf every few days. Though the RHS is around 0.8m from the conservatory side glazing.

    Cheers

    F


    “Rivers know this ... we will get there in the end.”
  • Ferdinand2000Ferdinand2000 Posts: 537
    edited January 2021
    Piccies.

    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

    “Rivers know this ... we will get there in the end.”
  • Ferdinand2000Ferdinand2000 Posts: 537
    edited January 2021
    Update 5/1/2021

    (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.

    https://www.youtube.com/watch?v=slvGKU7HF6M

    F

    “Rivers know this ... we will get there in the end.”
  • A few minutes today looking at the temperature of the soil.

    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.

    “Rivers know this ... we will get there in the end.”
  • tui34tui34 Béziers, Herault, FrancePosts: 2,594
    @Ferdinand2000  Love it!!!  Nice to wake up to some decent music!  I think I will try growing some micro greens in (unheated) conservatory.  You are very convincing!
    A good hoeing is worth two waterings.

  • @Ferdinand2000  Love it!!!  Nice to wake up to some decent music!  I think I will try growing some micro greens in (unheated) conservatory.  You are very convincing!
    Cheers. I think I've posted all the detail.

    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. 

    “Rivers know this ... we will get there in the end.”
  • tui34tui34 Béziers, Herault, FrancePosts: 2,594
    edited January 2021
    I don't have the fancy lights, but there is an orange lit lamp post just outside.  May do the trick.  I'll start with some cress.  
    Oh yes!  Once cut, do they come away again or do you pull them up by the roots?
    A good hoeing is worth two waterings.

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