Can anyone give advice regarding the best size of cold frame or high tunnel (height and width), what type of venting is required (roll up walls and/or roof vent? For those of you in colder climates, what type of frost protection to you give in early to mid May? When do you plant the tubers in the tunnel? Is it the same time as when the field dahlias are planted i.e. around April 20 in Zone 5B? Should I buy rooted cuttings or tubers? Who are the preferred suppliers?

Thanks for any help you can give me!

I started mine indoors on January 15th, took cuttings, and got my first bloom on June 6th (actually before it went outside.)

I can't imagine where you are that you could put tubers in the ground on April 20th, or even the first week in May for that matter...I'd still be afraid of ground frost. Have you done this before? Did you do that this year?

I put out one well growing Lemon Tart (e.g. 18" tall getting ready to bud) on May 15th this year and it promptly died.

I haven't done a cold frame, but I would think that unless you're using your house as one wall, I'd be worried about frost leaching in to the soil under the frame. Maybe this isn't an issue, but it would scare me.

Cheers,
Russ

Actually, you can plant before the last frost. Usually, the a late frost will only affect the tips of the plants and they'll grow back. A hard ground frost that can penetrate 6" is highly unlikely in late April. Besides, a dahlia will only send up a shoot when the soil temperature is optimal. You just have to make sure the dahlia won't rot while its waiting to send a shoot. This is my second year planting that early and I haven't lost any due to frost!

Right now, I'm cutting anywhere between 4500 and 6000 stems per week so the type of structure I need is quite large i.e. greater than 15000 square feet.

The grower licensed to propagate cuttings for the Karma dahlias resides here in Michigan. You may purchase trays of Karma dahlias through the following representative vendors: Germania or Gloeckner.

We receive our trays in early March, and bump the cuttings up to 4" pots which are grown off in a heated seedling greenhouse for four weeks. The plants are planted in an unheated hoophouse/coldframe the first week in April. And, they generally start blooming the second week in May. This is when our markets start, and we have demand for blooms. For frost protection a layer or two of remay usually helps.

Many growers have roll up sides; however, we do not. Our hoophouses are situated with the prevailing winds with wide doors at each end. Generally, we have no problems with mildew since we don't water overhead. Drip irrigation lines are laid throughout the beds. There are three beds in 20 x 96 hoophouses. That is the size that is generally used for growers in areas with snow. These structures are gothic design houses for areas with heavy snowloads. This size house would hold 1,104 plants which would produce two stems or more per plant per harvest. We harvest two to three times weekly for our markets. We can harvest one day, go back out there they next day, and it looks as if we had never harvested the previous day.

Karma dahlias are wonderful for growing under these conditions because they can be planted on 12" centers, four rows per bed. The plants do not get bushy as many field grown dahlias typically would. Karma dahlias grown under these conditions provide long, strong laterals. The plants are tall as opposed to bushy. Each plant usually provides many, many blooms throughout the growing season. They are easier to harvest than field grown dahlias. So, that may be some consolation for having to be inside a 90 degree hoophouse during the day. We do, however, try to harvest early in the day, or later in the evening.

Generally, we grow the Karma dahlias to get us out in the marketplace early, and they take us up to the point where our field grown dahlias start producing. However, this year with the late spring, the field grown dahlias started producing at least two to three weeks later than normal. It is September, and we continue to harvest from the hoophouses as well as the field grown dahlias.

When we start harvesting the Karma dahlias, we usually think they are the most beautiful dahlias ever. Bloom size does wane a little as the season progresses. And, when we move to the field for harvesting, at that point we think the colors of the field grown dahlias are just more vibrant. Frankly, I think all dahlias are beautiful. It's just that we love the ones we happen to be cutting at any given time. Dahlia growers are like that.

Hope this information helps.

Trish

Just a few questions...your extensive replies are thought provoking!

What is remay? Maybe, we have it here but use a different name.
Which Karma varieties do you prefer? Since your climate is very similar to ours, I'd like to know your thoughts about the different cultivars.

Now for an outdoor dahlia question - which White variety do you use for your bouquets? My 'Brookside' is very unpredictable and 'Bride to Be' is very tender and bruises easy. If I had enough white dahlias for my customers, I'd be doing VERY well!

Thanks again. I hope you're doing well in Michigan!

Henry

As for the field grown dahlias, I understand the concerns with Brookside. I love this dahlia; however, it is sometimes rather unpredictable. It's also a bit stiff for our bouquets which tend toward whimsical. Try growing Blizzard and Sophie K. They are prolific bloomers. Also, try Magic Moment which is really nice for wedding bouquets. The tips have a touch of lavender; however, here in Michigan not so much.

As for the Karma dahlias in the hightunnels, a beautiful white is Maarten DeZwaan. It is white with a hint of lime green at the center. Beautiful dahlia. Many, many blooms throughout the season. Farmers market customers love this dahlia. You cannot grow enough of them.

The other Karma dahlias we prefer to grow under cover are: Corona, Corona Pink, Corona Red, Sangria, Lagoon, and Naomi. Choc will be available soon as a cutting. As of the 2008 season, they didn't have all the quirks worked out on this particular one. Anyway, those are our favorites. And, Amanda is currently not one of our favorites. Too much foliage, and not enough blooms. We no longer grow the yellow one either for the same reason. We like our Karma dahlias bright. Again, the whimsical market bouquet thing.

When I mentioned remay, I actually meant floating row cover, which is a lightweight spunbonded polypropylene. It offers the most effective protection from frost early on when growing in an unheated hoophouse. Johnny's Select Seeds carries Agribon; and, I believe they also ship to Canada.

We are finally getting some much needed rain here in Michigan. We thinks it's because we recently purchased 10,000 more feet of drip irrigation.

Trish

Isn't this weather wild and crazy! Here in Ontario, we've had a record rainfall this summer. In fact, I've found out that dahlias can have TOO much water. I've lost some of my roots at certain spots on my field. We've also had more hail this past summer than I can recall in all of my life! (Put it this way...I'm not in my 30's anymore!)

Just a few more questions on the Karmas if I may...what is your fertilizer 'recipe'? I currently use a slow release (14-14-14) that I place in the furrows when I plant. I'm not sure if that's the best method though. Also, do Karma's require netting or other support? Do you pinch them or is your first cut considered a pinch? Are there a lot of side buds that need to be removed when bunching? If there's one thing I find unattractive about dahlias is when the side buds appear above the flower in a bunch. That's something I don't allow!

Thanks again for your valuable advice!

Henry

We lost tubers to flooding in May this season. They just floated away never to be seen nor heard from again. Yes. Strange weather indeed.

In the hoophouse, we spread compost and till it in before planting the Karma dahlia plugs. We fertilize with a liquid fertilizer 10-20-20 through our drip irrigation line. This seems to work well.

We need to get manure spread on certain sections in our fields at some point this fall; and, if it continues to rain, this will prove to be quite the challenge since we are blessed with both clay and sandy soil. But, get the manure on those sections this fall is a number one priority. At this point we will just hope for an Indian Summer. But, I have to tell you digging dahlia tubers in November is not fun. We did that last season. Not looking forward to a repeat of that.

Karma dahlia do require support netting. We use Hortonova netting, 6" squares. We lay the netting directly on the ground when we plant so we know to plant in every other square. We then raise the netting up to around 18" from the ground for support. We use only one layer of support netting. The first cutting of dahlias is sometimes challenging. But, we are so happy to see color that we don't complain -- much.

The Karma dahlia cutting arrive pinched supposedly. If we see a bloom deep in the plant, we pinch it out which forces the two laterals to bloom at the same time. There are not a lot of side buds that require removal. These side buds will be long and bloom a few days after you have harvested some of the other blooms. The advantage of the Karma dahlia is they don't have the unsightly buds appearing above the flower such as many field grown dahlias. What we find annoying is that if we leave any buds in a bouquet, the market customer ALWAYS asks if these will bloom.

One other advantage to the Karma dahlia is they can be harvested before they are fully open -- unlike field grown dahlias.

Here is a photo of Corona showing the Hortonova support netting.

Trish

Beautiful photo! I'm assuming the Hortonova netting is a plastic of sorts and you raise it using T-bars.
When watering, are you fertilizing each time or do you alternate between 'fresh' and 'fertilizer'?

Manure can be a beautiful thing! However, I've found that if it's too thick and not mixed well enough it holds the water too long but also can dry out very quickly. Also, its interesting what type of seeds sprout! It's all about the horse's menu I guess!