Zinnia Seedlings Dying - PLEASE HELP!

Nashville, TN(Zone 7a)

Hi -

I have grown zinnias from seed for the last couple of years with great and satisfying results. I start the seeds in Jiffy pellets under grow lights and have never had a problem until now. This year, the seedlings came up as normal, but when they're about 2-3" tall, they fall over and die! I've lost about 80% of all my seedlings. I thought I had been careful to avoid overwatering, which could cause damping off.

Any ideas of what could be causing this? Is it too late for me to plant a new batch of seeds??

Thanks for any advice!

Natasha

(Daniel) Mount Orab, OH(Zone 6b)

Zinnias can be planted right up until 2 months before frost date. I do not know what might be causing the death of your seedlings. I had the same happen to my Japenese Morning Glories in peat pellets earlier this Spring. Direct sowing Zinnias is almost always more successful than starting indoors.

Ottawa, KS(Zone 5b)

Natasha,

Your zinnia seedlings apparently have classic Damping Off disease. I prefer starting my zinnias in square clear orchid pots, instead of Jiffy pellets. I use Premier ProMix BX with extra Perlite as my starting/growing medium. I water from below by adding water to the tray that the pots are setting in, and I include a small amount of soluble fertilizer in the water. You can also keep the surface of your growing medium dry by having a small fan blowing on the pots.

You can still have plenty of zinnias by planting them directly where they are to grow outside. As Daniel said, Zinnias can be planted right up until 2 months before the first frost date. I plan to continue planting zinnias outside for at least the first two weeks of July.

I like the square clear pots because you can see the roots inside and get a good idea of how root-bound they are becoming. When you see a lot of roots it is time to re-pot to larger pots or, weather permitting, set the plants in-ground outside.

ZM

Thumbnail by Zen_Man
Nashville, TN(Zone 7a)

Thank you DM and Zen...

There is a new (and unfortunate) discovery:

I was inspecting the affected zinnia seedlings very, very closely and I found very tiny red dots under the leaves and some along the stem. I believe these may be spider mites! UGH! I have never ever had to deal with these before.
I ended up disposing of ALL my seedlings. I think the problem is indeed a combination of damping off along with spider mite damage. It almost sounds contradictory, as I thought mites prefer very dry and hot conditions, and it's been moist and room temperature all these weeks under the lights.

I will adopt the advice you both provided and will be planting seeds directly in soil this time. I'm just heartbroken, because I am now completely out of a few zinnia varieties that I can't seem to find again online. I do have several crosses left from last year that I do want to experiment with, so all is not lost, I suppose.

Thank You,

Natasha

(Daniel) Mount Orab, OH(Zone 6b)

You're very welcome, Natasha. Good luck with getting rid of those nasty mites!

Ottawa, KS(Zone 5b)

Natasha,

"I found very tiny red dots under the leaves and some along the stem. I believe these may be spider mites!"

I've never known spider mites to infest zinnia seedlings. I have had serious trouble with fungus gnats, thrips, and aphids on large plants of indoor grown zinnias. But the primary problem with seedlings is Damping Off.

The only control for Damping Off is prevention. A sterile growing medium and small electric fans to create air circulation which dries out the surface of the growing medium are recommended.

Did you see any of those red dots move? Unless there were huge numbers of them, they shouldn't have been able to suck enough plant juices to kill the plant. Mites can be controlled by a systemic which makes the plant sap poisonous to them. But you shouldn't have to fight mites on seedlings.

You might need to take steps to prevent Fungus Gnats. Their maggots feed on the roots of seedlings, and can they can do a lot of damage. The adult gnats flying around are annoying, but they don't hurt your plants, except to lay eggs that hatch into voracious baby maggots.

"I ended up disposing of ALL my seedlings...I am now completely out of a few zinnia varieties that I can't seem to find again online."

What varieties? I might know of Internet sources for them.

ZM

Nashville, TN(Zone 7a)

Hi Zen_Man...

Yes...those nasty things moved! I spot killed them with a q-tip and rubbing alcohol. But, I no longer think that was the reason for the mass zin death. I think what you mentioned is correct....damping off. The odd thing is that I DID use sterile growing medium and I DID use a fan for air circulation. I actually grew these in the same ways I did before - this is why losing so many this year has baffled me.

Is it normal to encounter fungus gnats every single year on indoor seedlings (I grow flowers, vegetables, and herbs from seed)??? I get them every year and they drive me nuts. I keep their numbers down by spraying the soil surfaces with a solution of hydrogen peroxide and water, but if you know of a better way - I'm interested to know. I don't want to use chemicals harmful to humans or pets since these are indoors.

As for the varieties of zinnias I lost...many of them were my own crosses I made last year. The remainder were various kinds: Benary series, giant cactus, Whirligig, Candy Mix, giant dahlia-flowered varieties, etc. Have you ever grown "ZOWIE Yellow Flame"? Your thoughts? I'll be planting those for the first time this week.

Do you have any advice as far as soil (for zinnias) goes? What do you amend with? Fertilizer? Fert schedule? Year before last, I knew next to nothing, and haphazardly amended with greensand, bone meal, coconut coir, worm castings, and compost. I just added things I found locally, not really knowing what each would do. I had THE BIGGEST and best zinnias that year with hardly any mildew/fungal problems at all. Last year, I added Osmocote, peat, a little compost, and the zins were nice, but not as robust and floriferous as the prior year.

By the way - where did you find those clear pots? I love them!

Thanks again for sharing your experience and zinnia wisdom :)

Natasha

(Pam) Warren, CT(Zone 5b)

This year- from advice found on DG - I sprinkled cinnamon on the soil of all cells and pots- et voila! No gnats. If I forgot and one or two started flitting around, I'd sprinkle again and that would be the end of them. I also used diluted peroxide in all watering, including wetting the planting medium before using. No damping off. That was some feat, because as a weekend gardener I use capillary matting over trays filled with water under everything.

Good luck!

Pam

Ottawa, KS(Zone 5b)

Natasha,

"Is it normal to encounter fungus gnats every single year on indoor seedlings (I grow flowers, vegetables, and herbs from seed)??? I get them every year and they drive me nuts. I keep their numbers down by spraying the soil surfaces with a solution of hydrogen peroxide and water, but if you know of a better way - I'm interested to know. I don't want to use chemicals harmful to humans or pets since these are indoors."

It is normal. I rely on one product, Mosquito Dunks, to prevent fungus gnats. They are a safe biological control for mosquitoes and also for fungus gnats, because both mosquitoes and fungus gnats belong to the insect order Diptera.

I place a Mosquito Dunk in a big Ziploc bag, put the bag on a concrete floor, and pound the Dunk to powder with a small hand sledge. I pour the powdered Dunk into a gallon jug of water and shake it up well to produce a stock solution of Bacillus thuringiensis israelensis. I add a dash of that stock solution to every gallon of dilute nutrients that use. That makes my growing medium immune to fungus gnats.

If an adult fungus gnat flew in the door and laid eggs on my medium, the Bti (Bacillus thuringiensis subspecies israelensis) would kill the eggs on contact, preventing fungus gnat maggots even before they got started. Incidentally, you definitely want to prevent fungus gnats, not just to avoid the clouds of adults in your house, but more importantly you want to prevent their maggots from devouring the root hairs of your plants. The damage done by fungus gnat maggots feeding on your plant roots will seriously stunt your plants, and possibly kill your plants. An infestation of fungus gnats is bad news for indoor gardening. I know how bad fungus gnats can be and that is why I always use the Mosquito Dunks in my indoor gardening.

Mosquito Dunks are a known control for fungus gnats. The adults don't eat the Bti, so they aren't affected, and that has been the reason why so many people have reported that Mosquito Dunks are ineffective against them. But Bti is very effective at eliminating fungus gnats at the egg-maggot stage in their life cycle. Incidentally, the adult fungus gnats don't harm your plants, except to mate and lay eggs on your growing medium. It is their maggots who do the damage.

"Do you have any advice as far as soil (for zinnias) goes? What do you amend with? Fertilizer?"

Zinnias prefer a sandy loam for good drainage. I use Miracle-Gro Tomato Food for my zinnias (and for my tomatoes). It has extra magnesium, as compared to other Miracle-Gro formulas, and it works well. I apply it as a drench or spray to foliar feed, and I water my zinnias with some Miracle-Gro as well. The combination of irrigation with soluble nutrients is frequently referred to as "fertigation". When you are feeding your zinnias, you are also feeding your soil.

"Have you ever grown "ZOWIE Yellow Flame"? Your thoughts?"

Zowie Yellow Flame is great for landscapes and for butterflies. It is an F1 hybrid, so the seed are expensive, but the resulting plants are reasonably uniform. Zowie is an award winner (AAS 2006), so it has performed well in their trials. It is not to my taste, because it "throws pollen" and has a tall pollen cone. The Zig Zag specimen in this picture is an example of a zinnia that doesn't have a lot of pollen florets but has the same basic tri-color coloration as Zowie. The advantage of Zowie is uniformity. The Whirlygigs, Carrousels, and Zig Zags have many bicolor and tricolor combinations, but are available only in mixtures (Zig Zags have been discontinued, but I am growing some this year from old seed).

ZM
(not associated with any product or vendor mentioned)

Thumbnail by Zen_Man
Nashville, TN(Zone 7a)

Pam -

Thank you so much for the cinnamon tip!! I will definitely try that as a safe alternative. I was only spraying a solution of hydrogen peroxide on surfaces - I didn't realize it was safe to use as a drench to prevent damping off. What ratio of H2O2 to water do you use?

Zen -

Thanks for the tip of using MG Tomato fertilizer on zinnias. How often do you apply this?

Interesting note about Zowie Yellow Flame...maybe I should isolate it from the rest :)

In your experience, how long, on average can zinnia seeds last when kept airtight in a cool, dark location?

Ottawa, KS(Zone 5b)

Natasha,

"How often do you apply this?"

It's sort of "when the spirit moves me". Probably about once a week on the average, except in wet weather.

"...maybe I should isolate it from the rest... "

Maybe. Even then, expect a few "love children" from Zowie in the rest of your zinnias. Not necessarily a bad thing. Zowie has some good genes. I just don't like the excessive pollen.

"In your experience, how long, on average can zinnia seeds last when kept airtight in a cool, dark location?"

You will probably get some germination after seven years. Zinnia seeds are fairly long lived. I notice very little decline in germination percentage after three years of storage. I probably should get a small refrigerator for seed storage, but currently I just store them in Ziploc bags at room temperature. The snack sized bags are handy, and a standard 3x5 card fits nicely inside.

ZM

Thumbnail by Zen_Man
(Pam) Warren, CT(Zone 5b)

This is the link to the article on using hydrogen peroxide:

http://www.using-hydrogen-peroxide.com/peroxide-garden.html

For me that and cinnamon made all the difference. I had a very productive spring, still trying to find enough time to plant everything!

Pam

Cincinnati (Anderson, OH(Zone 6a)


Hi, since this thread is about seed starting zinnias...could I ask a question?

I am trying to start Z. seeds in large window boxes on my deck. I used Miracle Gro potting mix. Now (three days later) I see that the zinnias (benary's giants) seedlings are emerging in patches in the window box.

Some spaces on the surface have no seedlings coming up and I thought I spread the seeds evenly. I didn't let them dry out.

Could this be a result of some of the seeds being covered too thickly with the planting medium? One packet said 1/4 inch. Then when I looked later at another it said 1/16 inch. Maybe I got it too thick? Or maybe the window boxes got too hot?

I thought Zinnias were pretty fool proof (except for damping off, of course).

Thanks. t.

Ottawa, KS(Zone 5b)

T,

"Maybe I got it too thick? Or maybe the window boxes got too hot?"

Miracle Gro potting mix isn't the best for starting seeds. There are special mixes for seed starting. Outdoors I start my zinnias in sandy loam, and a half inch isn't too deep in that. You might try digging around a bit in the areas that didn't produce zinnia seedlings to see if they got buried too deep. Or maybe you have enough seedlings. Benary's Giants are fairly large plants and each one likes to have quite a bit of space. For a window box I would choose something like a Magellan or Dreamland zinnia.

ZM

Cincinnati (Anderson, OH(Zone 6a)

Hi, Zen,

Well, I went out there and dug around in the soil with my spoon and found seed and some of it is just germinating this afternoon. (I thought maybe the birds got it.)

I think it's strange that there are parts of the window box where the seed germinated quite thickly two days ago and other parts where there isn't a seedling (just seeds) to be found. Same for both windowboxes. I'm thinking it must be the way the sun hits them in the morning.

Yes, I'm just using the window boxes on my deck railing to start the seeds to keep them away from the critters who love my garden. I'll transplant into the garden when the Benary's get bigger.

And I'm just being lazy with the Miracle Gro~~most times I try to use a real seed starting mix but this year I'm being rather casual. Next time I'll do it right!

Thanks for your thoughts. t.

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