Henry,

From your post, I'm going to go ahead and assume you have already planted your Karma dahlias out in the unheated high tunnel. There are two important things to remember about dahlias: heat and light. They don't tolerate extreme temperature changes within an unheated high tunnel. And, they also require 14 hours of light. When we picked up our order of Karma dahlias on March 18, we bumped them up into four inch pots, and grew them on for three to four weeks in the heated seedling greenhouse. At the time we picked up our order, we were only at 12 hours of daylight; therefore, we had to add that additional two hours of light via artificial light. We want to be able to keep the dahlia plants in continuous vegetative growth; otherwise, the plant will try to produce tubers, and/or set bud early.

The weather here in Michigan has been extremely overcast in April the last two seasons. There are days that we have had to leave the lights on in the greenhouse the entire 14 hours. And, the furnace, of course, has been running every night. With our weather, there have been days that the furnace ran the entire day.

Generally, the Karma dahlia plants are shipped already pinched. We do, however, find that some plants will try to set bud when still very small even under ideal conditions. We usually pinch out that early bud, and the plants grow on to produce well.

Hope this information is helpful to you.

Your flower farming friend in Michigan

Hi Trish,

Thank you for responding - it's good to hear from you again.

I think we've had very similar weather here in Ontario.

I didn't realize the daylength was so crucial. I received my cuttings from Bosgraaf during the first week of March, planted them into 4" pots and kept them in a heated greenhouse until last week when I transplanted them into high tunnels. The plants have only received natural daylight and have not received supplemental light. It was when I gave the first pinch, that some of the plants were showing early buds. (Bosgraaf only pinched one of my varieties because they were too tall for the box.) Based on your experience, will the plants continue to force early buds on short stems even after daylight hours naturally lengthen?

Also, when you mention extreme temperature changes, are you talking about very warm daytime temperatures and cool/cold nightime temps? What is the ideal daytime temp? Since my tunnels are not automated, its difficult to maintain a somewhat constant temperature. At what temperature do you start venting? And how cold do you allow it to get at night before you put remay over the crop? And...and...and I have so many questions!

I've put a lot of eggs into this basket! Although, I generally like to see buds in my plants...just not this early!

Thanks again Trish for your help.

Henry

Henry,

I believe we do have very similar weather. This is one reason we may find it helpful to share our growing experiences. Out of curiosity: Did you bring in the dahlia cuttings the first week of March because you didn't know how long they would be help up in customs?

We have been picking up our order directly from the grower in mid March. This is the only grower who is licensed to take cuttings of these patented varieties of dahlias. It is a partnership/agreement between the grower and the VerWer brothers, the patent holder in the Netherlands.

Because we pick up our order, many of the plugs are pretty tall. We assume because we don't have them boxed (and they wouldn't fit in boxes with their height), we take delivery of some good size plugs. We did notice when we bumped them up into four inch pots that a handful were already trying to produce tubers. Yes, the plugs were trying to produce tubers. Again, as mentioned previously, even under ideal conditions this will apparently happen for whatever reason. The plants mission is always survival.

In our experience, your plants will be fine after you pinch out those early buds. Our dahlias were planted out in the tunnel at the same time as yours. We're always on the lookout for a bud trying to set deep withing the plant, and we pinch those out. The plant will go on to produce two very nice and long laterals blooming at the same time.

As farmers, our tunnels are not automated. Our tunnels are situated with the prevailing winds which generally come out of the west. It is difficult to maintain a constant temperature. Ventilation, of course, is important to prevent the spread of disease.

We had two beautiful days last week for planting. And, then the weather turned dastardly. It was cold and rainy on Sunday. The low overnight was supposed to be around 44 degrees. The plants were not covered in remay. If the temperatures are in the mid 30s, covering them with remay would be helpful.

One question: Are you using drip irrigation in your tunnel?

We are continuously searching, learning, and sharing information regarding our favorite flower, the dahlia.

Hi Trish,

A cold and rainy Monday morning here in Ontario...The forecast is calling for more of the same until Wednesday.

No, it wasn't because of Customs that I brought the cuttings in early; it was because I wanted a larger plant when I planted them in the high tunnel. Actually, they (most) were all good size plants when they were transplanted. I don't know if that will give me a greater yield earlier in the season.

I'm relieved to know that the plants with early budsets will grow to be productive. That was causing me some anxiety!

It's interesting that you've mentioned the dahlias trying to produce a tuber early in its life cycle. What is the long-term effect of this?

I am using drip irrigation with a Dosatron injector. And, following Bob's VS advice, I'm fertilizing with 20-20-20. However, I'm not sure whether to feed on every watering or just weekly.

Thanks again Trish.

Henry

Henry,

Your weather is exactly our weather.

It's interesting that you've mentioned the dahlias trying to produce a tuber early in its life cycle. What is the long-term effect of this? Last April there were many, many days of cloud cover. Many of us cut flower growers noticed an impact on production. Ideally one can expect 12-15 stems per plant. Last season it was more along the lines of 8-10 stems per plant.

As far as fertilizing, when we picked up the Karma dahlia plugs this season, I recall Bob mentioning that we should be using a high cal fertilizer such as 15-0-15. We're going to have to verify the frequency; however, we never feed with every watering.

Warmest Regards,

Your very cold flower farming friend in Michigan

It was 37 degrees here overnight......with a wind chill of 32. How are the plants doing in the hoop house?

Hi Trish,

Sorry about the delay...I've been splitting tubers and planting Fruitilia roses.

My plants are doing fine. I did lose some top growth on some of my plants due to freezing weather. I didn't have the cloth pulled down to the bottom and I covered them up too late at night.

I have a question is about pH levels. I've never really paid attention to pH until this year due to growing in the hoop houses. Do you adjust for pH when fertilizing? My well water measures at 9.1. A little high...

Also - do you adjust for pH when watering your field dahlias?

Hope all is well at Banner!

Henry

My plants are doing fine. I did lose some top growth on some of my plants due to freezing weather. I didn't have the cloth pulled down to the bottom and I covered them up too late at night. Ahhhh. Yes. The life of a flower farmer indeed. We didn't get our plants covered until late either on those two nights of freezing weather. Sounds like Mother Nature did some pinching of plants for you. They will probably be a little cranky for a bit, but they will most likely be just fine.

Regarding the pH level. This may be the reason Bob suggested 15-0-15 fertilizer. We're going to feed this fertilizer through our drip line on the field dahlias as well this season.

The weather has been extreme on both ends of the spectrum. After the freezing nights, we had 84 degree temperatures. Today there is a hot, dry wind. It feels like we're in Kansas.

We were able to plant five 100' rows of Agrostemma this morning before the rain blew in. It was a gentle rain. The little plants are very happy for now. We may get storms later this evening into tomorrow.

Once again, the life of a flower farmer. It is never dull.