Seeking Support for Dahlia Support

cmcramer

...and trying out our new Forum.

I would like to experiment this season with the 'Swan Island' technique of support...or 'non-support' as it were....on at least some of my dahlias. Extra deep planting; hill up soil as plant grows like I do for potatoes; trim off entire dahlia plant once it reaches, say, 3 feet; hope for the best! But I start my dahlias in a greenhouse and transplant potted plants that are 8 inches to 14 inches tall. Can I bury those plants, specifically the plant stalks, deeper than they are in the pots? Can I bury them 4 inches deeper....6 inches deeper? Will plant stalks that have spent a few weeks above ground in pots *rot once buried in my garden? Thanks!

Darce

cmcramer
Oh I have never heard of this way - you have inspired me to do a little trial run too. I have a cutting bed that runs along an alley that would be great to get some non flopppity dahlias established

MissyWeitzel

I grow tightly spaced and corral my dahlias but I'm definitely going to try the hilling up method this season too. My poms were not close enough last season so they kinda fell all over the place after a strong bout of wind. Where those stems were laying on the surface of the soil, very nice tubers with super apparent eyes formed at each node. I'm all for more nice tubers and hopefully the deeper planting helps keep everybody upright too.

PNWGal

Swan Island hills up their plants several times over the course of the season, and it doesn't seem to cause any problems for them. Of course they also have fast draining soil, so maybe go lighter if you have heavy soil. Another thing Swan Island does that makes a big difference is that they are constantly harvesting cut flowers, and they cut the stems really long. So in addition to topping the plants when they get about 18-24" high, they are cutting way into the plants every time they cut flowers.

As for burying the pre-started plants, one consideration would be soil temperature at different depths. Is it cold or warm that far down?

SteveM

PNWGal As for burying the pre-started plants, one consideration would be soil temperature at different depths. Is it cold or warm that far down?

Great point, burying too deep in the early spring would slow the plant growth because of the cool soil temps. I have also found (unfortunately from experience) that burying the plants during the hottest days of summer will bake/rot the tender stalks and kill the plant.

PNWGal

SteveM I have also found (unfortunately from experience) that burying the plants during the hottest days of summer will bake/rot the tender stalks and kill the plant.

Good point, especially with the record highs we have been experiencing here even early in the season. I had several plants scorch at the soil line before I figured out to put mulch around the base of newly planted dahlias. Not tomorrow, do it NOW. The scorched ones regenerated from below ground, but they were still a month or two behind.

PegMc

I will share my experience from this last season in the hope that y'all won't experience what I did. I went for the hill method, in new beds/new soil ("50/50") for the dahlias. I also went for planting deeper, as I'd read that was advisable for southern states (Eastern NC here). I only re-hilled slightly 1x as I was taken down by "long covid' which basically saw me literally unable eventually even to have enough energy to get out of bed. Not to digress, but I won't be doing the same this year. I experienced what Steve did. I planted roughly 500 plants. Only 160 showed up,,, talk about heart sick. And get this, I had plants FINALLY showing up, breaking the soil surface as newly emergent plants in... September. All were planted 01-through 05 May.

cmcramer

Most interesting. Maybe I'll just try deep planting with just a few 'duplicates.' Thanks!

janell

Summer Dreams Farms, NW of Detroit, MI also hills his dahlias. He has sandy soil and mature trees surrounding his plot.

With my potatoes and asparagus crowns I will plant them in a trench, and slowly fill it in and then mound as the plants grow. I would try something similar with my dahlias if my windbreak were mature.

Here’s a photo from the 2021 Summer Dreams open house. The hilling is easiest to see on the row to the right.

Bessie

janell thank you for the photo, it's a great visual.

Teddahlia

Swan Island plants their dahlias about 6 inches deep. When they were about a foot or more tall, I saw a high school kid on an ancient small tractor slowly hilling the soil around the base of the plants. Note this is a two step process as planting tubers too deep initially is one of those dahlia disasters you hear about.

PNWGal

Swan Island - when the plants get too big to straddle with a tractor, their crews continue the hilling as they weed the fields (yes, they weed all 40-ish acres by hand!) But no rocks there. I really feel for the Summer Dreams folks!