General Dahlia Chat - 2025

Juliarugula · 2025-01-01T13:30:33+00:00

Justafewdahlias whew! Much better thanks! 😅

Justafewdahlias

SteveM Something I didn’t even consider! The heat attracting and insulating of the soil on the stem. Thanks for sharing these outcomes and observations! I am in the PNW zone 8b which feels kinda like the Goldilocks growing zone for dahlias out of all the zones. Are you in a zone with much more intense summer temps?

MIDahlias

I think my previous post(s) about pots have been archived. Two years of looking at the same stock from multiple sellers. When asking for advice in the past I was told 4" pots are not truly 4" pots and not order under 4" pots. I took this to mean make sure the pot itself is 4".

I finally I ordered 4.5" Square Form pots from Greenhouse Mega Store.
The website states:
4.5" square deep 4.25" L x 4.25" W x 3.75" H". (The opening is actually 4")
4.5" square 3.66" L x 3.66" W x 3.11" H. (The opening is actually 4" maybe a little bigger)

I currently use collapsible crates for almost everything and I can fit 15 - 32oz deli cups in my crates with no extra space for things to fall over. I was hoping to fit more square pots into my crates - because they are square. I didn't calculate the square pot sizes and my crate before ordering. I was hoping to fit more square pots in than I do the deli cups. Unfortunately, this is not the case. I can put 15 square pots in and then there is about 2" of extra space both length and width.

The pots I ordered are bigger than other pots I have seen. The quality is much better than those I've seen at my local nurseries. I definitely would suggest these pots to anyone looking to buy pots. I do wish I would have ordered 3.5" square deep - 3.5" L x 3.5" W x 5 H, so maybe I could fit 24 pots in my crates. (However, I still haven't done the math)

Teddahlia

Planting pot secret: a square flat will hold 16 "4"inch pots . Plant pots are designed to have the same bottom dimensions and larger pots(I call mine 6 inch pots) fit 16 to a flat also. I mix pot sizes in the same flat and that works fine for me. Large clumps used for cuttings need bigger pots. Most fit into the 4 inch pots(that are not quite 4 inches) and I have a mid size too. I seldom buy pots and have two sources. Plants we buy come in pots. We have neighbors give us pots. In the past, we did some dumpster diving at a retail nursery on "free potting day if you buy plants from us". Some large pots(7 inch) cost 35 cents each new . We have over 200 of them for free.

MissyWeitzel

I started my last handful of seeds yesterday and my grow room is just about bursting at the seams. It has been so slow to warm up in Michigan and it looks like it will be a while until I can start shuffling some things outside to harden off in the shade then out during the day and in the garage at night. The first two years I did 1000+ cuttings I had great success leaving them in 72 trays for months until planting out time without losing more than a handful during hardening off and after planting. The last 3 years I've lost significant numbers either during hardening off (I now set timers on my phone!), while in my grow room, or after planting out. This year I focused on size over quantity and grew everything in 36s from the start. I'm hoping the larger root system will keep me from killing so many this year!

(My favorite plant meme ever that I saved years ago from I don't remember where but it still cracks me up)

blown_dry

MissyWeitzel Oh, no!! 😆😆

Justafewdahlias

janell by using rooted cuttings are you overcoming virus concerns because with the rooted cuttings you are able to observe the plant’s growth and looks and all of that before committing to introducing it to the field? The few plants I did grow from cuttings I preferred because faster blooms and no worrying about if they will rot vs sprout

janell

Justafewdahlias ``

Justafewdahlias by using rooted cuttings are you overcoming virus concerns because with the rooted cuttings you are able to observe the plant’s growth and looks and all of that before committing to introducing it to the field?

That’s part of it. I have a fleet of basement pot tubers that I propagate from. If the leaves from those pot tubers test negative from DMV and TSV at Adgia twice about a year apart, I take cuttings from them to plant in my field. My goal is to grow clean stock.

I pre-sprout all new-to-me tubers, cull anything that is symptomatic, and test what grows well. If test results are good, I take cuttings of the newbies and they join other first year clean stock in the vegetable garden, 100’+ downwind of the dahlia field. There they are monitored for symptoms and their ID is confirmed. The mother plants stay in the basement to protect them from insects.

There is the added bonus that cuttings almost never rot, but it is heaps more work.

blown_dry

Today is gorgeous weather. I am going through my pots of last year's tubers (I don't know if they count as pot tubers) to do an inventory. So far the results are very good! Everytime I dump a pot and there's some nice little clumps or a sprouting tuber, it feels like Christmas.

Bessie

janell Wow, that is an impressive commitment and routine for attempting to keep virus free dahlias. Do you have a business that allows you to recoup the costs of testing? I'd be interested in your findings regarding varieties that you are able to keep virus free. Also, vendors you'd recommend purchasing from based on your findings.

Justafewdahlias

janell wow that is a very well thought out and committed approach to clean stock!! I never thought of the “no rotting” point of view….I had that happen to me last year with a few tubers that had good eyes and starting to sprout but it left some gaps in my dahlia garden

janell

Bessie Do you have a business that allows you to recoup the costs of testing? I'd be interested in your findings regarding varieties that you are able to keep virus free. Also, vendors you'd recommend purchasing from based on your findings.

Yes, I sell tubers and cut flowers. New introductions are much more likely to not be infected with DMV, TSV and TSWV. I have been able to find clean stock of less recent introductions from importers.

As for vendors of clean stock, below is a list of growers who I had success with in 2023 and 2024. Note that I am mostly shopping the new introductions in their catalogs:

Vendor - # clean cultivars obtained in 2023 & 2024
Stonehouse Dahlias - 10
River’s Dahlias - 8
Windstone Farm Dahlias MD - 5
Willow Lane Flower Farm IN - 5
Brambleside Farm - 4
Fleur Flower Farm VT - 4
Triple Wren Farm (cuttings only) - 4
Crazy 4 Dahlias - 3
Lobaugh’s Dahlia - 3
Breck’s Bulbs - 2
Coseytown Dahlias - 2
Goldenrod Gardens - 2

I’ve had moderate success at keeping clean stock clean in my field the last 2 seasons. In a random 10% sampling of my field in October 2023, I had zero TSV infections and 3% DMV+. My 10% sample last October turned up 0 DMV infections and ₁₀% TSV infection.

In 2023 I learned that multiple sequential negative virus tests are important. False negative DMV tests happen.

In 2024 I think that the native prairie surrounding my dahlias contributed to the TSV infections. The TSV positives were within 10’ of the perimeter. I moved my dahlia field to border the prairie last year. In 2023 the dahlias were farther south. The lawn was on 3 sides and strawberries were to the north in 2023.

Bessie

janell thank you so much for sharing the knowledge you've gained. I appreciate your attention to detail and keeping such good records. If you're comfortable, please let the forum know your business name. Otherwise, send me a direct message with the info. Thank you!

SteveM

janell Great info and record keeping!

As you know, there are two main sides in a dahlia virus discussion:

-There is the camp that believes in eliminating virus from dahlias as completely as possible using testing and tissue culture.

There is the camp that believes in roguing symptomatic plants but keeping the asymptomatic plants even if they test positive for virus. The goal is to promote the genes that provide virus tolerance in the breeding gene pool.

There are good arguments for both sides.

Krista

janell I, for one, am very excited about the orders I placed with you this year. There isn’t anything more frustrating than sprouting a brand-new-to-me tuber of a variety I’m super excited about that ends up arriving with virus.

Knowing I’m starting out with virus free stock makes a huge difference to me, regardless of what happens in the field. As a customer, it’s worth a higher priced tuber to have that peace of mind.

I appreciate your commitment to testing and providing your customers with clean stock from the get. I’ll happily be responsible for what happens thereafter.

janell

SteveM I agree that there are arguments in favor of both camps. In addition to my virus exclusion field, I have a breeding patch of asymptomatic infected dahlias at my parents’ farm.

However, having gone the “when in doubt pull it out” path for a decade, and now have gone a bit batty about virus, I much prefer growing clean stock. The plants require fewer inputs. To address pests eating my blooms and nutrient deficiencies, I used to spray neem oil, pyrethrin and foliar feed and also needed to bag blooms. I have not needed to spray, fertilize or bag blooms during the two seasons. I’ve probably jinxed myself, but the lack of bloom munching maniacs has been the best part of this experiment so far.

SteveM

janell Studies have shown that (at least some) virus-infected plants emit chemical signals that attract insect vectors. There needs to be more studies - I would especially like to know if plants that are infected, but tolerant will emit the same signals.

Keeping a virus-free population of dahlia plants would be extremely difficult for a home gardener. In addition to the expense of regular testing, a home gardener would need to find some way to eliminate the intrusion of pests from the neighbor's yard and eliminate any nearby host plants. My experience with control of tomato viruses has taught me that it is impossible to keep my field virus-free. Every season I start with clean stock but lose about 30% of my OP/heirloom varieties (little or no tolerance or resistance) to TSWV. (With tomatoes my main concern was/is TMV but I also test for TSWV and CMV). If there is no way to keep viruses out of my field I feel there is no reason to pay extra for virus-free dahlia stock. In my case it is better to grow asymptomatic stock that could be either clear of virus or tolerant of virus.

KitCMC

janell Krista
I also like the confidence that’s comes with purchasing tested tubers/cuttings. It’s the worst when after only a few inches of growth a plant is destined for the bin.

SteveM
Virus-infected plants attracting insects is fascinating. I am so curious about the biochemical pathways involved and the interactions between the virus, host, and soil dwelling organisms.

Justafewdahlias

Any advice on cut off time for digging and dividing tubers? How late is too late to divide? I overwintered some dahlias I grew in pots. I removed the tarp and mulch to see the tiniest sprout peeking through the soil, maybe 1/4 inch tall. But while I was removing the mulch I could see that the tuber has new roots growing. It was a variety I wanted to divide. Yes, I realize I should have done this sooner. Earlier felt so rainy and then all of a sudden it’s beautiful summer like weather here in the PNW. For some reason I think I heard that once the roots are growing you are not supposed to move them? But maybe I am confusing dahlias with another flower or bulb that doesn’t want its roots disrupted.

blown_dry

Justafewdahlias
I have run into this a number of times. Dividing in spring has always been how it works out for me. Go ahead and divide them. Existing sprouts generally aren't going to work out, but the tuber will make more. They will also make more roots.

Teddahlia

" For some reason I think I heard that once the roots are growing you are not supposed to move them? But maybe I am confusing dahlias with another flower or bulb that doesn’t want its roots disrupted."
Remember dahlias have tubers that hold nutrients to grow lots more roots. Disturbing roots only slows down growth for a couple of weeks. In the wild things eat roots but they grow lots more. if they want to survive. You are a very large insect that eats roots.
By the way, I am talkin about "hair" roots and they are the ones that pick up nutrients from the soil.

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