What Container Depth for these flowers?

ruet · December 19, 2009

I'm missing one important piece of info for next year — just about every site gives out spacing information, but not one mentions the depth of a container needed. I've been googling around to try and find the minimum comfortable container depth for the following:

Lobularia Maritima — Sweet Alyssum
Centaurea Cyanus — Cornflower aka Bachelor's Button "Bluet Bleu"
Boragino Officinalis — Borage
Cosmos Bipinnatus — Cosmos White Sensation "Purity"
Helianthus Annuus — Sunflower "Lemon Queen"

So far all I've been able to track down is that Sweet Alyssum has a "shallow" root structure, which is what, 4-8 inches? Found conflicting info on "Lemon Queen" Sunflowers, some sites say 10in depth is fine, others say 18in depth is an absolute minimum given the taproot... I figured since this variety was being used for the Great Sunflower Project, there would be more of this kind of info out there, but I couldn't track it down.

Any firsthand out-of-ground experience with these varieties?
Thanks!

habitat_gardener · December 19, 2009

Borage is the only one I've grown in containers. It comes up everywhere in my garden. Last year I had one that was over a meter (3 ft.) high, and much wider -- my books say it gets to 2 feet. I love this plant so much that I carried my first plant on a train 30 miles. Once it started reseeding, I repotted many seedlings to give away. Some of them bloomed when they were in small pots (under 6 inches), but never got bigger than 6 inches high or so. I got the best bloom from the ones in larger pots. I have one in a large pot, about 18 inches high, wide, and deep, but it's less than a foot high and doesn't have nearly as many branches as the ones in the ground.

If you get a big pot for the sunflowers, maybe it would work to grow the sunflowers and borage in the same pot? They both have taproots, though, so might compete too much.

ruet · December 20, 2009

Thanks for the info! How big was the biggest container you used?

I have spare 5gal, 10gal and can build larger/deeper if needed. This week I'm making 12-18 gal tomato SWC out of cheap clay roofing bricks. If it's a matter of a few more bricks and soil to avoid heavily rootbound, unhappy plants, sign me up. Just wondering where the container size stops being the limiting factor...

December 19, 2009	#1
ruet Tomatovillian™ Join Date: Mar 2009 Location: Madrid, Spain Posts: 42	What Container Depth for these flowers? I'm missing one important piece of info for next year — just about every site gives out spacing information, but not one mentions the depth of a container needed. I've been googling around to try and find the minimum comfortable container depth for the following: Lobularia Maritima — Sweet Alyssum Centaurea Cyanus — Cornflower aka Bachelor's Button "Bluet Bleu" Boragino Officinalis — Borage Cosmos Bipinnatus — Cosmos White Sensation "Purity" Helianthus Annuus — Sunflower "Lemon Queen" So far all I've been able to track down is that Sweet Alyssum has a "shallow" root structure, which is what, 4-8 inches? Found conflicting info on "Lemon Queen" Sunflowers, some sites say 10in depth is fine, others say 18in depth is an absolute minimum given the taproot... I figured since this variety was being used for the Great Sunflower Project, there would be more of this kind of info out there, but I couldn't track it down. Any firsthand out-of-ground experience with these varieties? Thanks!

December 19, 2009	#2
habitat_gardener Tomatovillian™ Join Date: Apr 2008 Location: California Central Valley Posts: 2,543	Borage is the only one I've grown in containers. It comes up everywhere in my garden. Last year I had one that was over a meter (3 ft.) high, and much wider -- my books say it gets to 2 feet. I love this plant so much that I carried my first plant on a train 30 miles. Once it started reseeding, I repotted many seedlings to give away. Some of them bloomed when they were in small pots (under 6 inches), but never got bigger than 6 inches high or so. I got the best bloom from the ones in larger pots. I have one in a large pot, about 18 inches high, wide, and deep, but it's less than a foot high and doesn't have nearly as many branches as the ones in the ground. If you get a big pot for the sunflowers, maybe it would work to grow the sunflowers and borage in the same pot? They both have taproots, though, so might compete too much.

December 20, 2009	#3
ruet Tomatovillian™ Join Date: Mar 2009 Location: Madrid, Spain Posts: 42	Thanks for the info! How big was the biggest container you used? I have spare 5gal, 10gal and can build larger/deeper if needed. This week I'm making 12-18 gal tomato SWC out of cheap clay roofing bricks. If it's a matter of a few more bricks and soil to avoid heavily rootbound, unhappy plants, sign me up. Just wondering where the container size stops being the limiting factor...