I grew them for a while and don't remember any problems. I gave them up because they required annual work, having to be lifted in winter and planted out again in spring and staked. Too much for me. But they were great flowers. I never sprayed them.

I should add, this was probably twenty years ago and we had a cooler climate then and plenty of snow. We still get winter chill (though it's true dahlias can't be left in the ground to face that). So I don't know if that makes any difference at all.

Thanks, Melissa.

When my one dahlia plant got covered with PM (you could not see any green on the leaves, it was so awful) I just cut it down to the ground and threw it away. After about 3 weeks, it came right back up again, and bloomed and did not get PM. Then in the Fall it died to dead dead, so I threw it away again. To my surprise it came up again about a week ago and now is 6 inches high and growing. So, it survived our normal very mild winter temps in the ground, and if it survives in future I will not have to lift the bulbs. (which I am too lazy to do anyway). I am glad to hear that you did not spray yours - do you remember what kind it was? I am hoping that Pacific Jewel is particularly susceptible to PM, and I can find a sort that is not. Thannks again -

Jackie

I bought a good variety of kinds, as an experiment, but I think they were all fairly tall sorts, many with large flowers--no miniatures for me! I don't remember disease problems with any of them.

You can try leaving them in the ground; I don't know whether they'll survive long term. When I come to think about it, I believe dahlias come from Mexico. In your shoes, I would take particular care to supply good drainage.

Jackie, I am very close to Southern France in my North-East corner of Spain, but my climate is not Mediterranean, we are too mountainous and just that bit too far from the coast to qualify. However, I grow a variety of dahlias perfectly well no spray. The only time one or two got powdery mildew was when I was away and they didn’t get watered. They do need a retentive soil enriched with organic matter and lots of regular irrigation to do well. It’s sometimes a challenge keeping them moist enough, but no more than roses or clematis. In fact, my summers are far too brutal for clematis, but dahlias thrive in heat so long as they have regular moisture at their feet.

I suspect the tubers, just like bulbs, need healthy foliage to keep feeding them going into winter, so if it’s been ravaged by mildew the tubers won’t have had sufficient stored energy to reemerge the following year - hence your low survival rate.

I don’t lift and store them. As soon as the foliage is blackened by the first frost, I cut them right down to the ground then pile on a big heap mulch to protect them during their winter dormancy. I did lose a few one particularly harsh winter, but that‘s probably much less of an issue for you. Nor should dry winters be a problem, they are more likely to rot in the ground from too much winter rain. As soon as you see new shoots emerging in Spring, start watering moderately, then increase as they bulk up.

In short, what they need is decent soil, non-to-little water in Winter, light watering as the shoots emerge in Spring and then plenty in Summer. Spraying is entirely unnecessary!

Melissa - thanks again, the fact that you did not have to spray yours is good news - maybe I just have to try different kinds.

Nollie - thank you so much! I have no control over rain in our usually wet Winters, (20-35 inches in 5 months), but I can make sure about good drainage, and water in the Summer, and lots of orgainic matter. My DH makes lovely compost and then ages it for 2 years - I just went out and put some around the emerging leaves of my only dahlia. It is on summer irrigation, but I will make sure to give it some extra. Water stress does make some of my roses get PM, so it makes sense that that might be true for dahlias.

Jackie

My winters are usually dry, Jackie, but I do have heavy clay soil so improving drainage is pretty key here too. Lucky you having a ready supply of homemade compost! I find the big dinner plate dahlias are far too demanding so I avoid those. I much prefer shorter ones that need no staking, are pollinator friendly and that have simple flowers. A few examples..

Little Swan:

Diabolo:

I lost this one and can’t recall the name:

Catherine Deneuve, needs some support, but I just let it drape over the bench:

Incidentally, when I searched ’dahlias’ in my photo file, quite a few echinaceas came up too. They also need good drainage but are much more drought tolerant. If you don’t grow them already, they might be a good substitute if dahlias prove too much of an uphill battle?

@jacqueline9CA, I peruse the Dahlia fb forums and think this post might be worth a read. Perhaps you might consider overhead watering. Hopefully, this link works. https://www.facebook.com/groups/265949743891471/permalink/2186119241874502/?mibextid=wwXIfr

I’ve purchased tubers from Micro Flower Farm , well-reputed dahlia supplier from the PNW.

jjkOC - good heavens, I would never have thought that overhead watering would prevent PM! That will be easy, as I only have one dahlia, and was thinking of giving it extra water this Summer. It is short so I can just water it with a hose - thanks for the idea.

Jackie

@jacqueline9CA, crossing my fingers for you!

I tried dahlias in my California garden for a couple years. They were robust but got a lot of powdery mildew. Eventually I gave up on them. But I do know gardeners in that same area who grew healthy ones quite successfully. I imagine it varies by cultivar, and I picked the wrong ones.

BTW, I used spray (overhead) watering in that garden.

Jacqueline -- I'm still fairly new to growing dahlias (year 2 in earnest, but have picked up the odd dahlia here and there from nurseries in the past). I started getting some PM on my dahlias toward the end of the season last year, but read that many consider that "normal." Given that I'm not a breeder or flower farmer, I want my plants to look good in the garden! I did spray some Neem a couple of times to keep it in check. But my Cafe au Lait (started from a pot in a garden center, this is its 4th year) didn't seem to get any PM at all. I did dig the tubers this last spring, because I have to plant in gopher wire cages, so I wanted to see what was happening to the tubers. They were growing more "up" than "down" -- but a couple had tried to grow through the cage. I've read that if you don't lift, you might want to do so every few years just to stay on top of the tubers. I've now told all my friends and neighbors that they are officially growing dahlias in the future! I'm a tiny bit nervous that if we truly get an El Nino rainy winter some won't like that...but I'm planting some perlite and pumice into my raised beds and pots in hopes that I'm not going to have to worry about rotting tubers. Anyway -- I don't want to have to spray my dahlias. I have a tough love approach to my roses -- if they are too fussy they have to go! Some of my roses for the last few springs have just succumbed to rust. which makes me crazy, as I've sprayed copper, then sulphur, then copper again in Dec, Jan, Feb. I think that I may have to get rid of those roses. Anyway -- hoping my dahlias don't need that much TLC!

Just went back through photos to see if I could see evidence of PM on my dahlias late season -- didn't see any -- but did see lots of leaves with leaf miner damage. I do plant to spray some spinosad this year! They really go for my roses and lemon tree, too.

Here are some dahlias so far this year:

DdinSB - thanks for the lovely pics! My one dahlia died completely dead last Fall, but then early this Spring sprouted back up (I guess this is normal). It is blooming, and so far does not have any PM.

I am looking forward to spending more time in the garden after this week - our house has been under scaffolding on all sides all the way up to the turret on the roof (3+ stories up) because we are having the outside of it painted. I have not been able to run in and out of the house as usual, because I always have to figure out whether I can use the front door, or the back door, or sometimes neither, as painters seem to be working everywhere - this has been going on since the begging of June. Very tired of keeping all of the blinds down inside all day, also. However, I am told they may be finished after this week, (or at least that the scaffolding will be coming down, and they will move to painting our separate garage).

Jackie

Good luck!

Thanks for sharing the article! Putting it on my roadtrip list!

My dahlia addiction is not quite as strong as my rose addiction but it’s a close second (I’m a member of San Francisco’s Dahlia Society of California and had so much fun at last month’s 100th anniversary show :)). It’s the rare plant in my deck garden that doesn’t get powdery mildew at some point of the year, but Small World, a white pompom dahlia, is the most consistently PM-free one I grow. It’s also a blooming machine!

I’ll share one of my favorite tips if you live in a warmer climate like mine — plant some of your tubers in late June, and you’ll have flowers all the way through Thanksgiving on plants that don’t look tired. As part of that strategy I also buy tubers on sale in June, when growers have marked them down for the year, then plant them right away. Some of my favorite suppliers are Swan Island up in Oregon, Fleur Farm in Vermont, and Fuirk in Tennessee.

My dahlias all grow in containers so I have to lift and store them in early December — I don’t have enough space to keep them potted + I think there’s a good chance they would rot when we have a lot of winter rain. But I also like the ritual of swapping them out for daffodil and tulip bulbs … then repeating the process all over again in the spring.

Here’s a photo of a small visitor my daughter spotted at the dahlia show last month.

Also I don’t spray in my garden!