Dahlias won't bloom

michimanSeptember 2, 2008

My father in law, who lives in Seattle, grows beautiful dahlias and gave me some of the bulbs (I live in Michigan). However, they will not bloom for me. This is my third or fourth year trying. I've planted them in good compost in full sun and water them sufficiently. I overwinter them correctly I believe. I have about 20 bulbs and got a total of 3 very small blooms.

Any ideas?

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sturgeonguy(5a ON)

When did you plant them?

How deep did you plant them?

Do you know what varieties they are, or how tall they should grow, or how big their flowers should be?

Do they produce foilage? If so, how tall have they gotten? Do they look lush?

Might you have varmits around that eat them?

Do you have jealous neighbors...;-]

Can you take pictures and send us a link?


    Bookmark   September 2, 2008 at 10:54AM
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What is your PH in the soil where you have planted them? Needs to be between 6-7. Compost is usually acid below 6.

Are you using a high phosphorus fertilizer to encourage them to bloom after they have been growing 60-90 days?

    Bookmark   September 2, 2008 at 9:02PM
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I plant the bulbs in May after danger of frost, approx. 4" deep. The soil is slightly acidic but not overly so. I do not know the variety unfortunately. The three blooms I've gotten are small and very light yellow.
The foliage looks very lush and green with no diseases--approx. 18-24" tall. No sign of varmints (two-legged or four!) that might be taking the blooms.

I'll try to upload a photo tomorrow.

    Bookmark   September 3, 2008 at 1:21PM
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sturgeonguy(5a ON)

One difference between a bulb and a Dahlia tuber is the way you plant them. Bulbs are typically planted pointy side up, whereas Dahlia tubers are planted laying on their side.

Shouldn't make a huge difference by this time of the year, but heck...we're grasping at straws...right?


    Bookmark   September 3, 2008 at 3:41PM
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Below is a link to a photo of the foliage and the blooms. The blooms aren't as big as they appear. The glass isn't a quart jar, it's a tiny juice glass.

Here is a link that might be useful:

    Bookmark   September 4, 2008 at 8:39AM
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sturgeonguy(5a ON)

Dahlia blooms can range in size from 2.5" (possibly smaller) to 14". Those blooms look perfectly normal to me, as does the foilage. Perhaps the foilage is a bit dense, how many plants are shown in that picture? However, I've got 29 plants as close together as you do and they're all blooming.

Given how well they look, I'd suggest its either a late blooming variety(ies) or you're not getting enough sun. You can try a couple of Jobe's Tomato Spikes on either side of the stem in case there's a soil composition issue.

FWIW, I have several varieties that have either just started to show buds, or have not yet shown buds at all...its not uncommon.


    Bookmark   September 4, 2008 at 1:17PM
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Poochella(7 WA)

The only other thing I can add to Russ's ideas are too high a nitrogen content in either your compost or your fertilizer. That would account for your lush foliage and fewer blooms. Well worth adjusting down the N, and trying again next year.

It's been a slow year here, if that's any consolation. But things are picking up full speed now.

    Bookmark   September 5, 2008 at 10:41PM
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rhodie_chick(z7 NY)

They need a lot of sun. R your plants spindly and on an angle (aka seeking sun)? Are U planting under trees? U will get a few flowers by Sept if they are in light shade but the best bet is full unabated sun for these guys. They need more sun that roses!! And also,like someone else said on this forum, a good flower fertilizer like Flowertone with high phosphate (the middle number) and some potash (the last number) works wonders. So a 5-5-5 is not as good as a 5 -15-10 for example.

hope this helps

Also you know you have to overwinter them, right? U R in wisconsin so they will rot if left in the ground. if U need any info on overwintering let me know.

    Bookmark   September 6, 2008 at 8:13PM
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Michiman, I think you are facing having tubers that will problaby never bloom IN MICHIGAN.
Take them back to the PNW and they will undoubtedly bloom their heads off.

This is a perfect example of why plants have hardiness zones, they will bloom when given their weather they have been propagated for. Hence the reason the palm tree is seen widely in the south.....and not in the north.
The impatiens you see flowering in Miami was propagated for flowering there. Send it north, and it wont....and vice versa.

Some trees, hardy to the east, take them to Minnesota...and they wont grow.

I suggest you make purchase of your Michigan tubers and watch the difference.

    Bookmark   September 9, 2008 at 3:58PM
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In other words, you can take the girl out of the west, but you cant take the west out of the girl.
You can take the plant out of the west, but you cant take the west out of the plant.

You should also try to give your dahlia as much sun as possible. An east facing sun is alright in mid summer...but its now getting late, the dahlia needs as much sun as what the time of season allows and its getting harder and harder to achieve decent sunlight intensity.

They should be allowed to remain in the ground until after a killing frost which will do the foliage in, then dug up, allowed to dry for a day or so before going into storage.
The process of digging, go wide afield of where you first planted them because what you planted is now larger...there's more of 'em.
Also, when you cut the foliage back, leave about 6" of stem remaining, this to use as a handle for picking them up out of the soil.

Keep the tubers in a bed of peat moss, dry sand or vermiculite and store where its cool, dark and dry.
You can dust the clump with garden sulfur to offset any chance of mildew or mold.

    Bookmark   September 9, 2008 at 5:51PM
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Missy, Traverse City, Mi Z5

I did not think that you had to check growth zones for dahlias.

    Bookmark   September 10, 2008 at 9:49PM
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Any plant that has been propagated in certain conditions, and among them, the fact that it can stand up to how severe weather patterns occur in a general area, then we say it has zone hardiness.

Plant hardiness maps show how North America is divided into 10 hardiness zones. Knowing the zone number for your area will help you determine which plant will thrive where you live.
The Pacific North-West has many zones, from 5 - 8 and 9.
The milder zones are close to the ocean where weather is moderated. The colder zones are further east, closer to the mountains that controls much of how winter is experienced, among which is precipitation.

This means that plants native to the Pacific Northwests Willamette Valley (Zone 7) will thrive in portions of other zone 7 areas. With added protection, maybe a plant can do well in zones higher and/or lower.
But crossing two zones...possibly your bulb crossed 3 or 4 zones, that is asking the plant to do something it wasn't born to do.


Hardiness zones can be expanded or reduced by manipulating the microclimate of a site. You can provide wind protection for a plant or make use of a wall that can reflect light and warmth back, or near a surface that draws sun for heat...such as a sidewalk or brick patio.

PRECIPITATION. We are well aware in the east how the PNW receives increased amounts of rain while we receive as much precipitation maybe, but in the form of snow.

Plants sometimes have very narrow zones where they thrive and as you move away, it becomes harder and harder to see them prosper. Florida is a mircro-climate unto itself.
The mild gulf water has a large influence on the whole peninsula. The oceans also play there part on the coasts.

Soil. The soil of any particular area may suit certain plants that thrive in it. Take a plant out of a narrow band of pH and feed it something foreign, it must have some kind of influence....good or bad.

    Bookmark   September 11, 2008 at 6:32PM
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sturgeonguy(5a ON)

While there's clearly a lot of research in your post Jeannie7, the answer you're providing michiman is, well, pure bunk, IMO.

That a plant has been grown in a zone does not make it native to that zone...it may make it hardier to that zone, but Dahlias are native to Mexico (zone 11), not the Pacific North West...so pretty much all Dahlias in NA are growing outside their native zone, by 2 or more zones. Weve got posters from zone 4 who have blooms.

Dahlias do not produce bulbs, which are stem tubers, they produce root tubers which are significantly different.

I seriously doubt that the tubers michiman received from his FIL were "hybridized" for the Pacific North West. Whod want such a plant? Whom would you sell it to, where would you show it? If it wont grow in trial gardens around the country, it cant get its ADS designation (AFAIK.) So unless FIL is genetically engineering some very specific Dahlias, and totally forgot they were hybridized for the PNW and gave them to michiman in order to prove his daughter made a bad choice of husbands (knowing that michiman would never be able to grow them in Michigan) I seriously doubt the tubers are the source of the problem.

This is further proven by the fact michimans tubers sprouted, and some flowers do appear. Clearly these are viable tubers IN MICHIGAN. Which part of michimans growth tells you they **cant** grow in Michigan?

This isnt to say that the PCN isnt a great place to grow Dahlias, but its not the only place for any varieties Ive ever heard of. Ive got 43 varieties of PCN grown tubers growing here in my zone 5b garden.

My point is that this whole zone hardiness bunk is misleading to anyone who might believe you. As long as you can provide a long enough growing season for your Dahlias, whether that is partly inside or not, you can have beautiful blooms practically anywhere. My average from 95 blooming plants right now is ~160 days from the time you take a tuber out of storage to the time it blooms. The quickest was 107 days, the longest 230, so as you can see there can be a huge variation even in the same gardens (as someone else pointed out, there can also be a huge variation in the soil composition/sun/water across a single garden.)

Michiman, my best suggestion to you for next year is to take your tubers out of storage any time after mid- January. Stand them up in some soil so the pointy end of the tuber is in the ground, and push them in about half the length of the tuber. You can put them 4"-6" apart. Watch the eyes form (if they hadnt before you divided them) and sprouts form. When the sprout is ~4" long, or has 3 or more sets of leaves, cut it off very close to the tuber. Put that cutting in a 4" pot with Miracle Grow Seed Starter mix. Water thoroughly and keep watered until you see new growth (remember, these arent tubers any more so you cant really hurt them with too much water.)

Grow these in your windows, rotating as needed (to keep the stems straight.) In May, when all chances of frost are gone (air frost, now youll be worried about the leaves being frosted so this is a little later than youd worry about frost for tubers,) plant them out in your garden as you would tubers. Leave them in their pots, or take them out...your choice. Leaving them in the pots will make for smaller more compact tuber clumps in the fall and theyll be easier to lift. In all other respects theyll grow identically either way.

You should have blooms much earlier this way, regardless the variety.


    Bookmark   September 12, 2008 at 2:28AM
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What sturgeonguy says about dahlias being bred for certain zones is very true. Any dahlia will grow anywhere if given the right conditions of lots of sunlight, good soil conditions & the right care. We send dahlias to trial gardens all over the country & they do well everywhere. Dahlias that we have bred here in the Pacific NW are growing all over the world-- even Capetown South Africa- talk about different conditions, different zones, different hemisphere & seasons & if that doesn't confuse a dahlia, nothing will!
When I was out at the greenhouse the other day I saw a couple of dahlias growing in the garbage pail- Walt had tossed them in May & they're about 3' tall & have buds on. No water all summer, no fertilizer, no care-- just trying to survive. There's also one that was dropped in bare ground by the driveway- ground as hard as blacktop- & it's growing, too. Dahlias LOVE to grow anywhere!
A lack of buds indicates a lack of phospherous. If the ph in your soil isn't right for dahlias you won't get blooms.
So start your dahlias indoors earlier, make sure they have good soil & lots of light, feed them a well balanced fertilizer (10-20-20 is what we use) a couple of times a season & stand back-- they'll bloom their heads off for you-- & speaking of that- be sure to dead head because you won't get as many blooms if you don't keep the dead heads off.

    Bookmark   September 13, 2008 at 12:41AM
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It's the 20th. Did they bloom?

    Bookmark   September 20, 2008 at 11:17AM
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