Came back from a couple days away and there was algae on top. That's what I get for top watering for once. Before someone lectures me, I know it was the top watering mixed with my grow lights because I made small puddles on larger pots and the algae only grew in that small puddle, not the entire top of the soil. Plus the ones I didn't top water had no algae.
I took this photo of the algae and underside of a leaf (nearly all of them look like this for pretty much every variety of tomato 7+) then painstakingly scraped off all algae and filled in with dry soil and butt chugged with a touch of Alaska Fish Fertilizer (about 1/3 the amount since they're still so young) since that's all I had on hand. It's been two days and they still look like this (sans algae of course.)
Feel like helping me out and telling me what I ought to do? I figured a phosphorus heavy fert would be good during transplanting into grow bags but we're still so far away from that. I plan to up pot to 4" pots soon, but not transplant to the greenhouse for another month at least. I was told by my neighbor who is a master gardener that phosphorus this early is bad for seedlings but her husband just died and I don't wanna pester her for gardening tips, you know? Any help would be appreciated!
by wanderinganus
4 Comments
The putple is normal and is from the artificial lights. Some varieties get purple leaves more than others. They will green up once they get under natural light.
The algea won’t hurt the tomatoes. I use peat pods and they get green with algea every year.
The advice about not fertilizing them.much at this stage is good to heed. It can result in nutrient lockout. It looks like this could be happening. Usually, they will recover once you pot these up, although they may be stuck for a week or two.
They don’t look stressed and i personally think top watering is better for tomatoes cucumbers and squash
It is normal as-in typical, but it’s not good. Basically, the plants can’t get enough phosphorus, potassium, calcium, and/or magnesium. Lots of factors can cause it at once. I have seen 100% green seedlings, I know it can be done.
– overwatering dilutes the soil juice/tea: likely, lots of moss in pick
– too small pot restricts root grow and top of plant has no restrictions, like a human with 3 foot legs and 30 foot torso: likely seems small but still early so okay there… I suspect the tiny cells made you overwater.
– actual nutrient deficiency in soil: unlikely, but start ferts at half strength when 2 real leaves poke head.
– wrong water: city tap water has ph of 8, tomato plants like about a 6.25 is my target. This made a big difference for me. Must be strict about a good water ph, ESPECIALLY IF YOU OVERWATER.
– inconsistent watering: they do like consistency, like they can predict when to use the water by when it arrives. They can also apparently predict the sun… I noticed on timelapse they start point leaves up slowly about an hour before lights shut off, changing schedules appears to confuse them for a day or two, or it’s just my imagination 🤣. You have 2 options: water deep, only when top 2 inches are dry OR water sparingly ensuring consistent moisture always. The first option is less total watering for you, every few days, but more fluctuation for the plant. The second is more watering, couple times a day, but you can really keep it pretty perfect, especially when you use the weight of the container to gauge moisture.
– stress: vpd over .8 is the start of stress for seedlings this small, it’s a spectrum that goes to about 2.0 practically speaking. Temp over 85 F is the start of stress here, lower a bit as ages. Humidity over 80%. PPFD over 300, start of stress.
I wouldn’t even try to stress the tomatoes to make em grow faster until you’ve mastered optimized growing resulting in practically no purpurple… at least, that is what I am writing to myself herein so I don’t have to relearn this again next year, lol
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Low temp & or lacking phosphorus