📌 Quick Summary (TL;DR): Early Blossoms & Seedling Temperatures
- 🌸 The Problem with Early Blooms: If your indoor tomato seedlings start forming flower buds too early (before they are planted outside), it’s usually best to pinch them off. Letting a small, weak seedling set fruit forces it into “generative” growth, permanently stunting the size of the plant and ruining your overall yield.
- 🌡️ Temperature Controls Flower Height: The temperature your seedlings experience in their first 10-14 days dictates exactly where the first flower truss will form!
- 📉 Cold Temps: Growing seedlings at cooler temps around 62°F (17°C) forces the first flower cluster to form very low (after the 7th true leaf).
- 📈 Warm Temps: Growing at warmer temps around 73°F (23°C) delays the first flower cluster, making it form much higher up (after the 11th leaf). This allows the plant to build a stronger, leafier vegetative base before fruiting.
What to Do When Indoor Tomato Seedlings Flower Too Early
Well, what am I supposed to do now?
I deliberately planted some early varieties ahead of schedule specifically so I could test topping them (cutting off the main growing tip) – Rozovyi Myod (Pink Honey) and German Red Strawberry. Yesterday I looked closely, and the tip of the German Red Strawberry looked like it had little balls forming… Today it’s crystal clear: they are flower buds! The sprouts emerged on March 8th. Today is April 6th, so they are 29 days old. I was planning to top one on April 9th, and the other on April 16th.
I just checked Pink Honey – it has a bud too… It sprouted on March 5th, so it’s 32 days old. I wanted to top it on April 9th as well. What do I do now? Those buds will definitely over-develop. Or maybe they’ll drop off… It would be great if they just dropped off, but what if they actually flower? I don’t want that, it’s better to just pinch them off myself if they don’t fall off naturally: there is still a month until planting out on May 7th, they have plenty of time to grow a new truss.
For the German Red Strawberry scheduled for topping on the 16th, I’ll definitely pinch the bud off, a new one will form by planting time.
The funny thing is, Burkovskiy Ranniy (an “early” variety, also from March 8th) shows absolutely nothing yet… So much for being early 👍😂
Valery, such beautiful little tomatoes, don’t ruin them! I used to mess around with all that nonsense too, they even called it the “Chinese method” of pruning. It didn’t result in any early fruiting. There were times when a seedling accidentally snapped, and when put in water, it grew an unimaginable mass of roots, but after planting it in the ground, it still stalled and stunted its growth. Don’t step on the same rake, as Luda says.
Some of my tomatoes are also starting to form little flowers, even Jeff Davis, which is a late-season potato leaf variety. Maybe it’s because I’m using my own saved seeds.
Well, there you go, I just had to show off my babies in a little photoshoot.
gala7496 (Galina) wrote:
Don’t step on the same rake, as Luda says.
Oh no, my rakes are the best rakes to step on!!!
Just joking.
Honestly, I grew these specifically for experiments… If I have to drag them out for another month indoors before planting, I’d have to pot them up into buckets. Not gonna happen… Better to run an extra experiment on them. And it’s not nonsense… If you time everything perfectly, the results can be quite good. I just failed to time it right this time-I needed to delay planting them out by about 10 days for my specific conditions. But that in itself is very interesting data… I’m satisfied… I got the information I needed.
And another thing: my main batch of seedlings was sown on March 17th. They mostly sprouted by March 22nd. From March 22nd to May 7th (greenhouse planting date) is 46 days! But now I know that buds can appear after just 30-35 days, so I will take this experience into account and deliberately stunt my main seedlings by lowering the temperature (if possible), potting them up (which delays development in my conditions by about 4 days), snipping off the cotyledons, and maybe the lowest true leaf.
Valtwelve (Valery) wrote:
What do I do now? Those buds will definitely over-develop.
Valery, your seedlings look amazing. Instead of topping them, it’s better to cut off the lower leaves (just not all at once, do it one by one) and pot them up into a larger container. You don’t need to cut the head off! Though, if you planted them specifically for that experiment, then go ahead and cut it, otherwise there’s no point in your whole setup.
But I am confident that if you pot them up into larger containers, they won’t drop the flower truss and everything will be OK.
gala7496 (Galina) wrote:
[Photo of seedlings]
Galya, they look so good! They need to be planted out soon. But it’s still a long time until planting season. You could also start snipping off the lower leaves. Not the whole leaf at once, but in sections: snip off one leaflet, then another later. It won’t harm them, but it will slow down their upward growth a bit. And dropping the temperature at night is a good idea too.
My tomatoes are still relatively small, but they look good – sturdy and stocky. By the end of the week, I think I’ll move them out to the greenhouse and just leave them there until it’s time to plant them in the ground.
The top layer of soil in the center bed of the greenhouse is already very warm, and the soil I have sitting in plastic grocery bags is literally hot to the touch. Once again, I’m convinced that planting early vegetables in bags is a great idea. That’s how I planted my Napa cabbage. Looked at it today and it’s standing there looking very cheerful.
Today I plan to prick out lettuce, parsley, and asters into cell packs.
I mentioned earlier that my lettuce refused to germinate this year. On my third attempt, I decided to sow pelleted seeds. I poured 10 pellets into a small cup, covered them with water, and let them sit for 12 hours. The pellets dissolved, I drained the water, and left the lettuce to sprout. It germinated incredibly fast. Out of 10 seeds, 9 are now ready to be pricked out. I really liked this method: no dirt involved, takes up zero space, and the seedlings are sturdy and uniform.
Aleksan9ra (Ludmila) wrote:
You could also start snipping off the lower leaves…
Luda, I actually just potted them up into large empty 2.2 lb (1 kg) coffee bags (there were even a couple of coffee beans left in the bottom of one bag, the tomatoes seem to love it!). They are sitting in a cool spot, I’m planning to plant them out around April 20th. These are grown from my own saved seeds, maybe that’s why they are growing so fast.
How Seedling Temperature Affects First Flower Trusses
So I tried growing my seedlings at lower temperatures this time –and once again, it turned out bad! The first flower truss appeared after the 7th leaf! Why do I need a flower truss so early? Fewer leaves mean a weaker plant, which means a smaller harvest!
“In indeterminate varieties, the height at which the first inflorescence forms depends on the temperature. At an average daily temperature of 62°F (17°C), the first flower truss forms after the 7th leaf; at 66°F (19°C) – after the 9th; and at 71-73°F (22-23°C) – after the 11th leaf.” – A.K. Akhatov, “The World of Tomatoes…”, page 45.
Should I try to raise the temperature a bit now? Or is it already too late for the first truss? The seedlings are 15 days old since sprouting-the first truss is probably already biologically programmed to form after the 7th leaf…
“To achieve high-set first flower trusses, you must maintain a temperature of 73°F (23°C) for 3 days starting 10 days after the seedlings emerge (specifically for the earliest planting dates). A low-set first flowering truss – after the 9th leaf-is achieved by lowering the temperature during the first 2 weeks after seed germination (specifically for later planting dates).” –M. Vysotska-Ovcharek, page 32.
I’m too late… It’s too late to raise the temperature now…
I guess I’ll just have to pinch off some of these early first trusses before planting them outside again. Because last year I planted out a Bychye Serdtse (Bull’s Heart) that had an overgrown blossom on it: the plant immediately shifted into generative growth. It was a pathetic, small plant that just tortured itself trying to push out tomatoes one truss at a time.
👨🔬 Editor’s Botanical Note: Valery hit the nail on the head regarding Vegetative vs. Generative Growth.
If a young, small tomato seedling sets fruit while still in its small starter pot (or shortly after transplanting), the plant enters a “generative state.” It channels all of its energy into ripening that one fruit instead of growing strong roots and massive foliage (vegetative state). The result is a permanently stunted, weak plant (“a runt”) that will give you a terrible overall yield.
If your indoor seedlings start blooming weeks before it’s time to plant them outside, the best thing you can do for your harvest is to ruthlessly pinch those early blossoms off!
