I’m growing them for the first time and only have two, ‘Embassy’ and ‘Nicholas’, as I don’t have much full sun getting into the garden. Both are 1.1m tall in 40cm diameter and 40cm deep pots. Difficult to see in the photos, but the plants are supported by black metal grow-through rings.
Re: feeding, I ran out of Richard Jackson’s Flower Power Plant Food early on so have been watering each pot with 12L of water containing Tomorite every week throughout a very dry summer.
Photos from this morning — ‘Embassy’, currently in a buds/young flowers phase after the initial flush of mature flowers
And ‘Nicholas’ — flowers are large and last well for about a week in a vase, just from cutting early in the morning and without the dip-in-boiling-water approach
Hi @Fire, my late-planted tubers have flowered (including recently Thomas Edison, which I gave away as a thank you for The Lark Ascending). Night Butterfly continues to be the most spectacular and floriferous. The surviving ones from seed are in the ground and very small. One has a couple of buds that appear frozen in time. But now, with the rains, all the dahlias are smothered in ants and aphids (the stems appear thick and black with them), and the molluscs are making a comeback, so not sure if anything is going to come of the seedlings. As you know, we have a puppy, which doesn't help.
The dahlias in pots have fared much better! Perhaps the proximity of herbs, nasturtiums, marigolds etc has helped them with pests, there?
I'm interested to know how your Waltzing Mathilda is doing @Fire. I've noticed a distinct colour change in the most recent flowers on mine, from multiple shades of orange and tangerine to an almost solid shade of cherry/peach. You'd think they were different varieties. See what you think of these photos, the first taken in June, the second today (taken with the same camera!).
@Athelas So good to see you garden here and with the roses. I'm glad you have had great success with the first time of growing dahlias - an uplift. Great photos.
@WhereAreMySecateurs - after the frost, it may be worth seeing if the seed grown plants have developed much of a tuber that might be good to keep. I'm glad Night Butterfly has done well. Good to hear that companion planting can help. I too noticed all the aphids have re-descended now the heat wave has finished. I don't have them on dahlias but my Nabob is encrusted with blackfly. Ugg.
@Plantminded My Matilda is similar but not so much pink - more peaches/corals but yes, variable and I like the changes. The pot I have her in is too small. She has not been very floriferous this year, but a bigger pot might help. I will get another tuber for next year.
My dahlia peak has passed, but some have been flowering since May/June so are finishing earlier. More and more are getting mildew. I've had a good year, so no complaints from me. No pest problems. I must have had 20 bunches of flowers this year from eight or so pots. My three dahlias will go in the ground next spring and that will free up some big pots.
@Plantminded I find flowers on some plants can vary in colour according to heat. Eg, I have a tender hibiscus houseplant that I brought form Belgium where it bloomed a rich golden yellow.  Here it is a rich sunset shade with ambers and oranges and soft reds graduating from the centre to the tips.
This year - 3 heat waves and some serious temperatures up to 52C in full sun and 44C in the shade - my dahlias all seem richer in colour than last year and I have whites, lilacs and assorted oranges and reds in different forms.  The downside is that the drough means they're doing it all on much shorter stems than usual so not so good for picking for the house.
Never mind. The bees and other pollinators have been enjoying them and the chooks go under the foliage for shade and cool as there is a seep hose to stop them (and the pumpkins further along) from drying out completely.
@Obelixx Are your dahlias in full sun? There have been interesting discussion about dahlias' susceptibility to sun scorch or wilt in direct 30o to 40o+Â sun.
Yes @Fire - fullsun but on rich soil and with the contents of the chook shed and baskets dumped on them all winter so plenty of nutrition and mulch.
Dahlias do come from Mexico which is equatorial so I really don't think they have a problem with heat or full sun but do suffer when thirsty.
From what I read, they don't natively grow in conditions much above 30oC. There are some links on this upthread. Reading about dahlia farms in very hot conditions like Texas, they choose certain varieties that seem happier to high heat. But it's interesting to know that yours do ok with high sun intensity with no problem (not so much to do with soill moisture or food but sun blaze).
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I’m growing them for the first time and only have two, ‘Embassy’ and ‘Nicholas’, as I don’t have much full sun getting into the garden. Both are 1.1m tall in 40cm diameter and 40cm deep pots. Difficult to see in the photos, but the plants are supported by black metal grow-through rings.
Photos from this morning — ‘Embassy’, currently in a buds/young flowers phase after the initial flush of mature flowers
The dahlias in pots have fared much better! Perhaps the proximity of herbs, nasturtiums, marigolds etc has helped them with pests, there?
Thanks for this thread, Fire. It has confirmed my need for 5 times as many dahlias next year! I'll keep them in pots though...
Btw no earwigs or slugs on my dahlias (in pots) and minimal aphids, probably because of all the little spiders, so I’m happy with that
This year - 3 heat waves and some serious temperatures up to 52C in full sun and 44C in the shade - my dahlias all seem richer in colour than last year and I have whites, lilacs and assorted oranges and reds in different forms.  The downside is that the drough means they're doing it all on much shorter stems than usual so not so good for picking for the house.
Never mind. The bees and other pollinators have been enjoying them and the chooks go under the foliage for shade and cool as there is a seep hose to stop them (and the pumpkins further along) from drying out completely.
Dahlias do come from Mexico which is equatorial so I really don't think they have a problem with heat or full sun but do suffer when thirsty.
From what I read, they don't natively grow in conditions much above 30oC. There are some links on this upthread. Reading about dahlia farms in very hot conditions like Texas, they choose certain varieties that seem happier to high heat. But it's interesting to know that yours do ok with high sun intensity with no problem (not so much to do with soill moisture or food but sun blaze).