MasonSebastian
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URGENT: Sunflower seedlings with yellow foliage?

Hi, I've been growing sunflowers since 10 days ago. Seeds germinated quickly and I have already atleast 5 inches of sprouts (I think I bought a mammoth). But yesterday I just noticed the FIRST set of leaves have yellowish coloration on their foliage, others have brown tip. 2nd batch of leaves are OK though. Is this normal? I just gave it 18-6-20 fertilizer to feed on, soil is moist (my last watering was last Sunday), temperature at full sun is at 33 to 36 celsius (Manila, Philippines).

They have also grown too tall for a seedling and I staked them since their stem are really really fragile (I snapped #1's stem :() and they have this weird bend. I already turned the pot around/ There are 15 of them in 1 plot, 3cms apart. Any help is appreciated. Thank you!

BTW, I staked them using 2 barbecue sticks, 1 on each side per sprout, and tied a nylon zip tie around them to support whatever angle they bend to.

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applestar
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Re: URGENT: Sunflower seedlings with yellow foliage?

I hope you meant 30 cm apart.... If they ARE 3 cm apart, they are too close and probably accounts for their not growing well. I would select best looking ones and eliminate the weaklings by cutting the off at ground level so as not to disturb the roots of the ones you are keeping. If any can be dug up without affecting the good ones, you could attempt to transplant them but it maybe too late as sunflowers grow deep taproot. If you want to try this, I'll go into more detail.

The fertilizer you used, if at full strength, sounds WAY too strong. If you have applied this fertilizer previously, that may actually account for the browning. Sunflowers have significant store of energy in their seed leaves.

They also need a lot of sun. How many hours of sun are they getting in this location? Fragile stems may also indicate not enough sun time.
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MasonSebastian
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Re: URGENT: Sunflower seedlings with yellow foliage?

probably 4-6 hours full sun. yes, 3-4cm apart :lol: but I am planning to thin them out and transplant the other bending stems onto a different pot. but from what ive read, they tend to bend down when they get no sun, right? i notice that everynight the leaves are touching the plant box border, then during the morning they are up again. but now they have a very weird bend so I staked them. i will post pictures later :) thanks

MasonSebastian
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Re: URGENT: Sunflower seedlings with yellow foliage?

:( they all died when I transplanted them individually in pots. I am using a compost soil mix, a light brown type of soil. What could have gone wrong? I planted them deep btw, like 4 inches below to keep the roots moist but not drowning.

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rainbowgardener
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Re: URGENT: Sunflower seedlings with yellow foliage?

MasonSebastian wrote::( they all died when I transplanted them individually in pots. I am using a compost soil mix, a light brown type of soil. What could have gone wrong? I planted them deep btw, like 4 inches below to keep the roots moist but not drowning.
Not sure without having seen it and not quite following all the above. But they already weren't doing very well to begin with. I have never had sunflower seedlings wilting or curving like that. They were leggy (too tall and spindly) which is usually from not enough light. They were yellowing. And then you force fed already suffering seedlings super-concentrated fertilizer. The general principle is don't fertilize (especially with synthetics) plants that are struggling. It forces rapid leaf/stem growth, when what you want is for them to heal, get sturdier, with better root systems. All that before you transplanted them.

"Compost soil mix" You mean a mixture of compost and topsoil? Seedlings in little pots need to be in potting soil, which is light and fluffy and very well draining. Light brown soil is usually dry, if moistened it should be dark.

"I planted them deep like 4 inches below" Below what? If you buried the stem 4" deeper than it was before, you likely just rotted the stem out. We bury tomatoes deeper because they have the interesting (and fairly unique) property of rooting all along the buried stem. Most plants do not:

"When you do plant your seedlings in the garden, do not plant them deeper than the level that they were previously growing. Planting them deeper could harm the stem and deprive the roots of essential oxygen."
https://www.wildflower.org/expert/show.php?id=9016

That was not written specifically about sunflowers, but it applies.

How were the roots looking when you transplanted? Did they have healthy root systems? Did you handle them gently in the transplanting process? Did they get watered in gently, but not left soggy? Lots of things can go wrong in there.
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MasonSebastian
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Re: URGENT: Sunflower seedlings with yellow foliage?

How can I prevent them from being too spindly/leggy? I replanted them in a container with coconut husk chips at the bottom, sandy soil with peat, and topsoil of mixed compost (I am using a brand called Gro-Quick). The root system is quite long and moist.

I guess I have a lot to learn though. And I thought my research was enough :lol: Anyway, temperature is blazing hot at 35.5C and the guides I read online is for much cooler environments. But I do hope I get it right next time. Thanks for the tips, very well appreciated.

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