Same Dahlias - Different Sizes

15 years ago

Last weekend, my wife and I visited the Mendocino Coast Botanical Gardens, where I noticed many of the same varieties of dahlias that I'm growing in my own garden. However, the size of these dahlias was quite different. Nearly all of the dahlias in their dahlia garden were comfortably grown on inverted tomato cages and grew to about four feet tall, while nearly all of the dahlias grown in my Zone 9 garden grew to be enormous beasts of plants, easily topping the seven foot mark. Dahlias such as Midnight Moon and Summer's End, which tower over my garden, were considerably smaller in the Botanical Gardens. To be honest, I'd much prefer these smaller, more compact, more easily maintained plants than the jungle I wound up with, which eventually became overcrowded and came down with powdery mildew. Might the Botanical Gardens be pruning their dahlias to keep them small, or could the Zone 9 heat (or other factors) be responsible?

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Comments (4)

plantlady2008
15 years ago
They might be cutting them off in mid-summer like Swan Island does to make them all shorter & more equal in height for their open house weekend.
raymondo17
Original Author
15 years ago
Is that a viable option, to just whack off the tops of the dahlias when they get too large? I realize that will set blooms back at least a few weeks, but it'd be worth it if I could keep my dahlia garden manageable for its small space.
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plantlady2008
15 years ago
Yes, Swan Island has an open house in the summer & they cut everything off at the same height so people can take pictures of the fields & they will be uniform. It will set the blooms back - you'd have to figure out how much bloom you want to give up & how long it'll take the plants to recover.
Do you "stop" your dahlias when they get to about a foot tall? This is done early in the season to keep plants shorter & bushier & doesn't get rid of as many blooms as mowing them off later in the season. This article on the Colorado Dahlia Society site tells you how to do this.

Here is a link that might be useful: Topping dahlias
raymondo17
Original Author
15 years ago
>Do you "stop" your dahlias when they get to about a foot tall?No, I didn't do that this season. I'll definitely try it next season and hope it prevents them from becoming 8' gangly giants with tall stems that snap off as the flowers bloom. And that link you provided showed an excellent how-to. Thanks so much! :)