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Potting up sunflowers

enceladusenceladus Posts: 27
Hi all,

My sunflower seedlings (coconut ice) are 20cm tall, grown in a module tray, and really need potting up.

They are strong plants but I thought it would do them good to be potted up deep with maybe 5cm of stem under the soil.

Does anyone know if that would that cause the stem to rot? Is there any benefit to planting deep?

Grateful for any advice. Thank you :)


  • Janie BJanie B LincolnshirePosts: 848
    I'm in same position as you! First time I've planted sunflowers, and they are in 9cm pots, desperate to be moved on ... but to where? pots? garden? what soil? Any hints, please! 
  • enceladusenceladus Posts: 27
    Oh dear, mine would probably love a 9cm pot! Might have kept them in their little modules too long but they look happy and green enough. 

    I’m sure there are loads of sunflower pros who can answer our qus. 
  • Sam 37Sam 37 Posts: 999
    In the same boat as you and not an expert by any stretch of the imagination; but, I think this should help all of us! sunflower seeds into individual,a cool but bright place.
  • enceladusenceladus Posts: 27
    Thanks, Sam! That article suggests planting them the same depth as they currently are. I’ll go with that! Cheers. 
  • WildFlower_UKWildFlower_UK Cambridgeshire, UKPosts: 215
    I grew giant sunflowers last year for the first time, so definitely not an expert (see below - they were so lovely!). But I didn't burying them deeper than their current pot at any point and they were fine. They seem so flimsy when young, but their stems really do beef up when they grow! You could also lightly tie them to a support if they're floppy - I did when they were both in a pot (using a wooden skewer) and when they eventually went in the ground in early June (using a bamboo cane), adjusting the ties as they grew. I can't quite remember what pot size they were in by the time they made it out into the garden, but I would think that being in a module tray much longer won't be that good for them as they'll quickly use up all the nutrients. If you can see any roots peeping out the bottom, best to pot up into 9cm pots with any multi purpose compost. Plant out in early June - just be sure to harden them off for a week or so beforehand (leave outside during the day and bringing them back in at night) so they get used to outside life! 

  • enceladusenceladus Posts: 27
    Thanks so much for telling us about your experience. Those sunflowers are glorious  <3

    I hope you’ve got more on the go this year! Glad to hear (and see) that the stems thicken up. I’ll pot mine up this afternoon then and give them a little stake. I’d best start the hardening off process now too! 

  • WildFlower_UKWildFlower_UK Cambridgeshire, UKPosts: 215
    I hope it helps @enceladusother! I'm indeed growing sunflowers again - the same giants (although less success with germination this year) and some smaller Ruby Sunset bush variety, too. I forgot to mention that also remember the most important ingredient - lots of sun! I've found even in the two days since I've moved my young 25cm sunflowers from a fairly sunny window spot to an even brighter spot (lots of juggling around inside at the moment!), they've grown straighter and stronger. Good luck and come back here in a few weeks with some photo updates, I'd love to see how you're getting on :) 
  • Janie BJanie B LincolnshirePosts: 848
    Thanks for the link @Sam 37 and thanks for sharing what you've learnt @WildFlower_UK... those are indeed magnificent sunflowers... Mine are both pink ones... Ruby Eclipse and Claret, both 6ft-ers, so don't expect them to end up as tall as yours!
  • Sam 37Sam 37 Posts: 999
    edited May 2021
    enceladus said:
    Thanks, Sam! That article suggests planting them the same depth as they currently are. I’ll go with that! Cheers. 
    Janie B said:
    Thanks for the link @Sam 37....

  • CrazybeeladyCrazybeelady WarwickshirePosts: 515
    Mine are in the garden already, they've been out about 2 weeks, but they're about 3 feet tall. I planted them way too early and they got too tall for my windowsills! They were doing my head in so they had to go!
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