Dahlias left in the ground

[Rain]

Do many of you leave your dahlias in the ground over winter? If so, could you please give me any tips?

Last year I lifted them all and kept them in a cardboard box in my shed but many did not grow again this year. I read on the RHS site that in heavy soils (which mine is) there is a higher risk of them rotting in wet weather, but I think there's a lady on the site who leaves hers in.
  When I cut them, should I cut them below ground level? I was thinking of covering with straw to save them a bit from the cold and then some permeable ground cover that I have, or possibly the other way around, with the straw on top of the ground cover... does this sound like it could help? Or should I be using a ground cover that's not permeable?
 
  I really don't know what I'm doing in terms of leaving them out, so any suggestions are appreciated. I'm guessing I don't cut them with a bit of stem showing as I would if I were storing them indoors, or the rain would just get in them and rot them...? Thanks.

[Rain]

[valmarg]

If you dig dahlias up they like to be stored in very dry conditions, and fairly warm.  Your shed would  have been a bit cold and dank for them.  The attic would be more suitable, but just remember they are up there!!

If you are going to leave them in the ground by all means protect them with straw, etc.  In the ground they like a well drained soil, so if you have heavy clay that is going to keep the tubers wet all Winter, the will not like it.  Don't cut below ground as the new growth comes from the old main stems.  Unlike potatoes, you cannot pull off a tuber and expect it to grow.

Unless I have a variety that I really want to keep, I grow from seed each spring.

Having said that, I have quite a few dahlias in the garden that have overwintered satisfactorily where I didn't get round to pulling them out.

valmarg


valmarg

[raisedbedted]

I always leave mine in the ground both at home and at the allotment.  Soil at home is very heavy clay.

You are right in cutting back the stem, or folding it over so that water doesnt enter the stem that way - I have had some rot from that method.

I tend also to put a 6" layer of manure over the top of the old plants, the mulch keeps them protected a bit and feeds them the following year.

Digging them up, storing them in a dry place etc I always lose about 1 in 3 each year so now I dont bother.

[Pigletwillie]

I also lose a lot if I dig them up so now plant with a couple of inches of grit underneath to help drainage. After the first frost, which generally blackens the foiliage, I cut them of at ground level and then put 4-6" of mulch over the top. I rarely lose any now.

[markfield rover]

I leave mine in too, but I also make sure to place a few slug pellets   under mulch in early Spring otherwise the little
sweeties will have the lot.

[Baaaaaaaa]

Have a look at "Dahlia tubers ...urgent help needed" from  April 27, 2007 :-

http://www.allotments4all.co.uk/smf/index.php/topic,30896.0.html


also

http://www.allotments4all.co.uk/joomla/component/option,com_smf/Itemid,91/topic,28501.0
http://www.allotments4all.co.uk/joomla/component/option,com_smf/Itemid,91/topic,28522.0

[Rain]

Unless I have a variety that I really want to keep, I grow from seed each spring.


valmarg

Thanks to everyone who posted. Valmarg, it's interesting that you grow from seed each year... I have bought packets of dahlia seeds before but there isn't a great choice at all. Do you know of any specialist dahlia seed sellers? Or I guess I'd save the seed from this year's flowers? Will they grow as big next year from seed as they would from tubers?

[markfield rover]

If it is of any use Rain I get my seed from The National Collection, It is pot luck, real mix puts tension into ones life!
£2.50 generous pkt.www.national-dahlia-collection.co.uk

[valmarg]

/quote] valmarg, it's interesting that you grow from seed each year... I have bought packets of dahlia seeds before but there isn't a great choice at all. Do you know of any specialist dahlia seed sellers? Or I guess I'd save the seed from this year's flowers? Will they grow as big next year from seed as they would from tubers?
[/quote]

I don't know of any specialist dahlia seed companies Rain.  I usually get my seed from Moles Seeds.  They tend to have larger quantities of seed at more reasonable prices (plus vat) than the retail companies.

When you grow from seed the plants do produce tubers, and if there is a plant you really, really like you can use any of the above-mentioned methods of keeping them.

And you can save seed from your flowers this year.  What you end up with will be hybrids, and you could be something new and fantastic, or rubbish.  My grandad's speciality/hobby was cross-pollenating plants.  One of his dahlias I insisted was called after me, ie Valerie Margaret.  It was a white pompon with a pale mauve centre.  Sadly, I am now extinct.

valmarg

[Rain]

I find all that cross-pollinating fascinating... I'm guessing it's time consuming, but is it a relatively simple process? I'd love to have a go, just wouldn't know where to start.
  So, you think for sure that any seed I save this year from my flowers will be hybrids next year? Is that the same as saying that this years dahlias are F1's?

  Sorry if I'm confusing matters further.

[valmarg]

No Raine, it's a bit more complicated.

F1 varieties are first cross, and to produce these each year the seed companies use the same parents to produce seed.  If you collect seed from an F1 plant whether it be fruit, flower or veg you will get a hybrid.  They will not come true to the original F1 variety.  You could end up with something much better, and as I previously said you could end up with rubbish, but if you don't try you won't know!

Particularly with tomatoes, you can save the seed of 'heritage' varieties, and they will come true.

You can save seed from anything in the garden - what you end up with is a mystery, but that's where plant breeding starts, and that was what fascinated grandad.

Fuchsias are one of my favourites.  At this time of year they are setting seed, they look a bit like cherries.  You can take the seed from them, and grow new varieties.

Busy lizzies is one of my favourite summer bedding plants.  Whilst it takes a lot of heat in January to get the seeds to germinate, it you collect the seeds now, you will get a much better germination rate, admittedly F2s, but the end resulting flower display will be very good.

valmarg

[Rain]

Thanks valmarg, that's what I thought with F1's. I grew courgettes this year from saved F1 seed last year... some courgettes looked mostly dark green all over, and others were widely striped, like a marrow, and these both grew on the same plant!