How much water is to much and when is it not enough? Sometimes we learn the hard way…it’s called the “School of Hard Knocks”. I’m telling you it is a hard but very valuable teacher.
Just the other day I had some mold problems with this tray of Brussels Sprouts, remember? If not, go back and read that post here. Anyway, first thing I suspect when I see mold is to much moisture from over-watering, so I cut back on the amount I was using to bottom water the plants.
Two days later I went in to water my microgreens and see the wilting corners of my beautiful greens are withering as though they are thirsty. This is a sign of under-watering, so there has to be a “sweet spot”…right?
I routinely rotate the tray’s position on the shelf by 180 degrees, to eliminate any problems due to an uneven shelf, floor or house. My grow rack is also in front of a window so the sun shines on the back of the rack. The sun shines along the trays edges longer than the entire tray. This provides good, natural light but also can cause the tray to dry out faster, especially along the short ends of the tray.
The Evidence
Brussels Sprouts had mold from to much water perhaps. See bald spot in middle where I removed the fungus? I treated it (see my earlier post). I also cut back on the quantity of water I was giving this tray. Two days later the mold problem was solved but I ended up with dry, wilting corners.
To little water creates dry spots and causes the plants to droop and look kind of wilted. I suspect the corners of the tray are lower than the center leaving them high and dry. These are new trays, so I’m not sure, I’ll check for any evidence of bowing or distortion once I harvest the trays.
In an attempt to revive the plants and to verify whether it was a watering situation, I did a light mist on the dry areas. I did this twice and the next morning the same corner (as pictured above) had “recuperated” from the watering disaster.
This corner I did not mist, so I could compare results and ascertain, was it lack of water or something else causing the wilted looks in the corners. As you can see the sprouts are top heavy and appear to be wilting at the corner.
Conclusion
The results are in. The corners of the flat are wilting due to lack of enough water. This seems to occur more frequently in the shallow 1020 trays for microgreens than the other trays I use.
So far the deeper trays, either with the lattice bottoms nor the 5″ containers sitting in deep (2.5″) trays haven’t encountered this dry corner scenario. However I must note the differences between the shallow trays with coco coir and the lattice trays with coco coir are the plants grown with the lattice trays are much bigger root systems and aren’t as delicate as the smaller Brussels sprouts. I use the lattice trays for crops of wheatgrass or peas. When I use the 5″ containers and the 2.5″ deep bottom trays I am growing hydroponically with hemp fiber mats. The high absorption of the water into the mats would keep the roots more evenly moist than the other 1020 shallow trays with coco coir medium.
Observations
I’m not noticing this happening when the tray is in blackout and watering from above. Of course, this stage of the plant development is really to early, and the plant not grown tall enough to see the wilting.
There are three different ways I could remedy this situation.
Water from above by misting even after introducing to the lights
Water from the bottom but top water (mist) the corners
Water from the bottom and tilt the tray so the water travels to each corner in turn, tilting as you go before putting tray back on shelf in the rack
Final Solution
The first two options above, using a top mist to water the plants would encourage to much moisture within the “canopy” of the plants. Air circulation is important to keep mold and moisture from becoming issues. Top watering (watering from above the plant) unless a very fine mist, can crush the tender plants and leave “flat spots” in your tray, where the plants look like they are laying down instead of perky and standing up straight.
The last idea, tilting the tray and letting the water slosh around to each corner in turn before returning the track to the rack, is the best option. This allows the roots in the corners to get the first drink and wet those thirsty roots. An occasional mist on the corners are okay, if needed, but refrain from misting the inner most areas of the tray where moisture and fungus can hide.
My decision became even easier after my discovery this morning when watering my trays. Stay tuned for more to this saga.
Feature photo by Lukas Bato, Unsplashed.com all other photographs are by me.