@Fire what a lovely thing to do for your neighbours, I would have been so happy to receive that, well done.  I can remember my Dad growing dahlias and as a child finding tubers stored in various places and thinking they were extremely strange, and it all seemed a bit of a palaver 😂  So it’s taken me a while to have a go with them, the dahlias I grew last year I left to overwinter in the ground and I was lucky they all survived, probably beginners luck! My photo of my Cafe au Lait was purely down to my iPad, I cannot claim any credit at all.Â
One of my Dahlias looked horrendous by the end of Monday, even having had plenty of water. I thought it was a goner but it had tentatively recovered by yesterday morning, so I put an umbrella over it to protect it from the sun!!
I thought dahlias would be sun loving plants - like bushy salvias - South American creatures of the heat. I wonder if it is the huge temp change and change in sun intensity that mollucks them rather than the heat itself. Most plants can't take huge, sudden shifts.... Just a thoughts.
They discuss tree dahlias and propagating dahlias from tubers mid-season (just digging a bit of tuber out and potting it up). But most interestingly Alan notes that it's always worth potting up a random tuber "sausage" without an eye (a visible growth nub) because something may well happen. It may be a long shot, but he says it's always worth it (if a sausage falls off the main clump). I have heard dahlia nurserymen say this before now. It's not worth it if you don't want the faff, are new to it, or don't have the space to try. However you will often see comments that say that potting up one sausage will never bring on a plant, and this isn't true.
Also Alan is a big believer in feeding less and often. Rather than a weekly full strength feed, try a half strength every time you water. I think hungry plants like dahlias could benefit from this.
How do you go about dealing with slow to get going/small tubers? Have mentioned further back in the thread at how I've noticed being further north and no longer having a conservatory to start them in has made a noticeable impact on the speed at which a lot of mine are taking to grow.
That being said, by this time of summer I'd be expecting them to have their march on given they've been potted for ages.
Am I as well writing them off for use in my big pots this year and just try and re-pot (and feed) them to suit as the summer progresses to try and get their size up?
@Dirty Harry I think your dahlias need bigger pots asap. They will need food in their soil. If you potted into MPC including fertiliser in the spring, it will have used it all up by now. If you can give them direct sun, lots of space for the roots, food and generous water, I expect they will be fine. I find dahlias are not plants to skimp on - water loads, feed loads, as much sun as you have. I mix some manure into my pots to add richness.
These are the size pots I use. I go as large as I can. The larger the pot, the more moisture and food it will hold. It also helps to make large plants more stable in wind. (Pic from May. London.)
I'm not a great believer in "potting on". I tend to "go large" off the bat, if I can.
Posts
Copperboy (a new favourite, the colour is so beautiful)
Cornel Brons
Cafe au Lait (immense blooms, doesn't seem to last long in the vase)
Nuit d'Eté and New Baby (both very tall and floriferous!)
That being said, by this time of summer I'd be expecting them to have their march on given they've been potted for ages.
Am I as well writing them off for use in my big pots this year and just try and re-pot (and feed) them to suit as the summer progresses to try and get their size up?
Case in point-