Blown centers halfway through growing season

dahlia1972 · 2023-08-22T00:09:24+00:00

I'm in RI, and several of my plants are producing smaller blooms with blown centers after 3-4 successful flushes of perfect large blooms. Very disappointed,...

cmcramer

So interesting. We'll be watching our Mystique carefully next year! Thanks, Ted!

dahlia1972

This is happening with about half my plants. If it's genetic then I need to toss them. I wish there was a way to ensure that I'm getting good stock when I purchase tubers.

SteveM

dahlia1972 This is happening with about half my plants. If it's genetic then I need to toss them.

It's probably not genetic if it is happening to half of your plants and they were fully double earlier in the season. There are a few environmental factors that can cause open centers:

fertilizer. If you are cutting heavily you will need to fertilize a couple of times during the growing season.
too hot or too dry. A long hot spell or insufficient water can cause open centers.

Just about every way I stress a plant will put the plant in "survival mode" which results in open centers . For example, I sometimes "force" open centers for hand crosses (mid summer) by growing the plant in an undersized pot and under-fertilize.

Teddahlia

When I said "genetic", I assumed the grower was using fertilizer and water as any farmer would do. You are growing a crop and the plants have to have enough chlorophyll to make energy to grow flowers. Professional farmers often use chlorophyll meters to verify that the plants have enough fertilizer and they do not skimp on nitrogen. The "bloom" fertilizers are poison to dahlias and they only add too much phosphorus to the soil and seldom do they have any nitrogen in them. So, if you have done your correct fertilizing and watering and the plants give up, it is genetics.

calico20hill

How do we factor in the admonition not to give nitrogen after the beginning of August so that the tubers will store better, with the need for fertilizers to prevent open centers.

And on the other hand if an August bloom starts out promising but then opens it center after a few days does that mean it might be worth keeping and giving a late feed the next year?

SteveM

calico20hill How do we factor in the admonition not to give nitrogen after the beginning of August so that the tubers will store better, with the need for fertilizers to prevent open centers.

It takes a severe lack of fertilizer to force open centers and with normal fertilizing practice there would not be a problem. If the lack of fertilizer was this severe a grower would also see a decline in the plants. I have only done this once.😊

calico20hill And on the other hand if an August bloom starts out promising but then opens it center after a few days does that mean it might be worth keeping and giving a late feed the next year?

I wouldn't assume an open-centered seedling in August would improve with fertilizer. If it has been very hot, I would give an August seedling until Fall to improve. If it has been normal growing conditions and none of the other plants are showing open centers then I would toss the seedling.

Teddahlia

How do we factor in the admonition not to give nitrogen after the beginning of August so that the tubers will store better? I have not seen a scientific report on this but only so called hear say. Many times hear say is wrong. Always too much of good thing is bad thing but the plants need green leaves to grow flowers. If one is a big time cut flower seller, you have way too many tubers to worry much about a little rot.

AKWindWatcher

I've found that cold temps (like we've had all summer) will cause some open centers. Basically the plant is going into "I've got to reproduce because it'll be time to die soon" mode.

Dahlia53

AKWindWatcher This is helpful to know; thanks. We had a very cold and windy spring last year and summer was cooler than usual, which is usually cool to begin with. I'll maybe try another year of these varieties before tossing.

calico20hill

My garden all seems to have decided it is fall and winter is coming and they need to make seeds fast, Maybe they know something I don't? The weather is just getting comfortable to me, as our days are back in the 70's range and nights are not near frost. However, the mildew season is starting. And there are fewer daylight hours where the shade of the garage now blocks some morning sun and where the shadows fall in mid afternoon instead of evening.

Dahlia53

Hi - about open centers; I hope this is not too silly of a question but if a dahlia has open centers all season, should I assume it is bad stock and get rid of it? My friend gave me Crazy4Teedy, which I loved in her garden. In my garden, the centers were blown all season in hers, centers were closed. She has good drainage with lots of sand in her soil. I have clay with bad drainage. I did discover that in my heavy clay, in some beds, things were bone dry not very far down, even with careful regular hand watering. But plants right next to Teedy didn't have the blown centers.

I had another dahlia plant in another bed - a mis-labeled UFO that had blown centers, but then it righted itself. I don't know why in either instance.

It's very confusing for an avid hobbyist - but I have noticed the difference between 'bad' stock and good, and I seem to be getting a lot more bad stock these days - and I don't buy that variety again from the same grower - or even buy from the same grower again if most of them seem to be bad stock.

Honnat

Dahlia53 If you are not selling your tubers, there's no problem in trying your stock another year with maybe just one or two plants to see what happens. Plants under stress do tend to blow their centers more easily. It's the plant saying "Hurry up and reproduce! We're gonna die!" There could have been some stress going on that you don't know about.

SteveM

Dahlia53 . I'll maybe try another year of these varieties before tossing.

If you have the room, that is what I would try.

Teddahlia

Blown center varieties are usually bad stock that has sported negatively. Some varieties never sport to open center and they probably have redundant genes for closed center.,

katyaker

I have a Ferncliff Illusion I got years ago from a nearby grower. At her house it has perfect blooms. At my house, 10 miles away, all flowers are open center all season long. After a couple of years I of frustration, I got another tuber of same variety from her and same thing - open centers all season. I am giving up on it this year.

My plants do have a greater tendency to sport than anywhere else I have ever heard of.

Teddahlia

Radioactivity? Have you done one of those radon tests in your house?

blown_dry

Honnat I have read that theory before, but it seems unlikely as species dahlias show their centers immediately at all points of the blooming season. The only purpose of flowering for a plant is because it's time to make seed. Covered pollen centers/missing pollen centers/sterile flowers in dahlias only are perpetuated because of human intervention. I'm guessing that growing conditions later in the season just don't allow the maximum petals the plant is genetically capable of.

Teddahlia

My experience is that many varieties never blow their centers prematurely. As breeder, that would eliminate that variety from our breeding garden.

AKWindWatcher

I ditto what has been said already. Plants under stress will do whatever they can to reproduce and that means making sure the pollen is available as fast as possible. In addition to getting a soil test, I'd suggest maybe trying to grow in a pot with a good neutral soil like ProMix and in as an ideal location as possible. Basically, try and eliminate negative soil & environmental factors as much as possible for your "one more year" experiment. Microclimate conditions can play a big difference in how plants do up here. (I'm in AK.)