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Tall dahlias in pots for slug protection?

This is my first year planting dahlias and wondered if for slug protection, I could plant tubers for 5 foot tall dahlias, in large plastic pots partially sunk in the flower bed with copper tape around the top edge of the pot. This works well for 6' tall sunflowers. I don't know how tubers work in the ground. Do they send out roots or fungal connections that require lots of space around the tuber? If they do then I expect a pot may be too restrictive. I will be feeding the dahlias regularly, so would pots be OK?




  • BiljeBilje Posts: 725

    I grow a fair number of dahlias mostly in borders. I find if they are started in pots and planted out when well grown the spuds/snails don't bother them. I have trouble if I leave tubers in the ground the slugs like the newly sprouted shoots. If you do grow in a large pot keep it well fed, tomato fertiliser 3 times a month and keep well watered. They are thirsty greedy plants.

    They produce roots from the tuber and the tuber increases in size over the summer. Hope this helps.

  • Zoomer44Zoomer44 Posts: 3,267

    I grew a 'Sir Alf Ramsey' in a trough last year with other plants. The trough was possibly 30cm deep, it reached a height of about 4ft and needed support but produced a couple of huge flower heads. 

    Agree with Bilje, they do need alot of water. I fed mine on home made seaweed feed. When dug up at the end of the summer the roots had taken over most of the trough and the tuber, as one would expect, was very large. 

    Slugs shouldn't be a problem once the plant is well established. Copper is a well known slug/snail deterent, putting gravel as a mulch around potted plants acts as a further deterent and will help retain moisture in the compost.     

    With the correct care and attention, most things can be grown in pots... I'm sure someone will be long now with a list of stuff which can't image

  • Thanks Bilje, thats very helpful indeed. What size are the well grown shoots when you plant out. Mine are about 3 or 4 inches but I'm afraid of planting out too late in the year.

  • Thanks Zoomer44 for your helpful comments too. I'm building up a picture of what to expect.

  • Hostafan1Hostafan1 Posts: 33,288

    I grow about 200 dahlias and , as stated above, once they're a decent size slugs/ snails have no ill effects. I start mine off in a cold polytunnel then plant them out when they're a bit bigger.

  • BiljeBilje Posts: 725

    Hello again NF, I plant from about 4 inches high I gamble with an early start here in the N E about mid May and just keep going as I clear ground. Still got a few to do and some of them are  a foot tall. Once you plant yours they will soon make growth, flowering will just be a little delayed but will continue to flower until the frosts. I sprinkle blood fish and bone (BFB) around the planting hole when I plant but I still feed with Tomato fertiliser . They are addictive so be careful haha.

  • Thanks Hostafan1, Mike Allen, and Bilji again.

    Most of mine are at differing stages of growth and mostly less than 3 inches. A few are just reaching 4 inches so I'll take your advice Bilji and plant them out today. I have made a note re the BF&B.

    I don't like the idea of killing any creature unnecessarily so copper tape is my preferred method. Aparantly slugs have a memory and avoid the copper tape when they have been shocked by it. I found that a late evening stroll through the garden with the aid of an empty yoghurt pot, a small stick and a torch, I could round up about 50 slugs per trip. I took them across the road and dropped them into a field there. At first I wondered if I was making any difference as there seemed to be an endless supply of slugs filling up the yoghurt pot each night, but to my surprise after about a week I was hard pressed to find 5 per night.

    I visited Sarah Raven's garden last year when she was growing 6' dahlias. She grew them through home made square lattices raised on stilts to support them. Wow what an impressive and colourful display. It gave me the inspiration to try something similar. Mike, I haven't decided yet on how I'll support mine, but supports would have the added benefit of preventing slugs and snails from starting at the top! Thanks for the tip.

    Thanks again to all who have replied and helped me.


  • Thanks Verdun.

    You may have read this is my first year after being wowed at Sarah Raven's garden last year.

    My tubers and plugs have all arrived now;

    Royal Bumble 35" tall

    Blue Bayou 36-48" tall

    Edge of Joy 39"

    Twinnings Smartie 30"

    Unwin Mixed 24"

    Happy Wink 18-24" dark leaves

    Peaches and Cream 60"

    Rosella 60"

    Ferncliffe Illusion 60"

    then for good measure Hellianthus Maximilliani 84"

    They are all at different stages of growth and as its my first year I started a bit late I suppose but I hope to start in April next year when I will have the tubers at home i.e. not having to wait for delivery.

    I'm excited at the prospect of having a wow front garden for the first time! Thanks for your input.


  • PS I chose all my Dahlias to have open flowers to be bee friendly. We'll see!



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