You started them way too early for your zone. They need only a 2 week start and should be planted out when all danger of frost is gone, which is 2 months away for you.

What I would do is plant them in a big planter pot, 6" apart, don't pinch, and let them flower indoors, putting the pot outside on warm days and bringing them in at night.

If you want to, you can pinch the tip and wait for them to grow side shoots, but that could take forever. I'd start over the end of April with new seeds and call this a learning experience. lol.

I would definitely pinch them - I take them down the right above the third leaf. Yes it will take a little time for them to branch out, but you have time before they can go out.

I start lots of annuals inside. You did jump the gun a bit with these. I have some dwarf zinnia started, but they are easier inside since they dont get so tall. Even those I didnt start til Mid March. The rest of my zinnia I'll start at the end of April.

mandolls, now you have scared me. My packet said to start 6-8 weeks ahead, I am 6ish out, and started almost all my zinnias (all tall) on april 1....guess i will be pruning hard.

LOL annuals are so much harder than lettuce!!!

Zinnia grow really fast. Anything tall that grows fast you need to be careful of inside. Even with good lights and a fan on them they are just not going to be as strong and sturdy in an inside growing environment. You dont want to have to stake zinnia.

I pinch back pretty much all of my indoor annuals. It slows down the foliar growth, keeps them from spending their energy trying to make flowers inside and makes much bushier, sturdier plants - eventually with a lot more flowers.

This year I started my petunias extra early. I let most of them bloom a little - just because the flowers were making me happy. But at this point I am snipping them regularly. Instead of plants with 5-6 runners I now have 12-15 growing tips on most of them.

We finally have weather in the 50's in the near forecast. I plan on potting the Petunias up into hanging planters and taking them outside daily. It will give me more room under the lights to start the rest of my seeds :)

Hi SouthCountryGuy ,

"My packet said to start 6-8 weeks ahead..."

That advice was questionable. Zinnias will typically make their first bloom in 6 to 8 weeks unless you remove the central bud. I have had indoor zinnias open a first bloom in as soon as 5 weeks.

" I am 6ish out,"

By that, do you mean that you are Zone 6? If so, you might not be in too much trouble. When is your safe no-frost date?

ZM

Thanks for the advice. I think I will pinch these off and if needed, I can plant seed again later. Can I plant the pinch off's and have them grow as new plants or will that not work? I hate to throw something away that I could have flower later.

Thanks for the advice all. I have had some zinnia before just never done them from seed. Seems like I am getting a pile of bad advice of late LOL. Wish I had lots more seed to start again.

I am about zone 4b-5a, last frost date varies with who you talk too (I am in a micro climate) and ranges from about May 14 to May 22.

Bacon - I havent tried rooting cuttings from zinnias before, but I assume you could do that. Give it a try.

I have had the best luck rooting things in Pearlite - or 50% pearlite 50% vermiculite. Warmth and humidity will help. I put about 2" of wet pearlite in a clear, lidded clam-shell box or domed tray and place it on the top shelf of my lighting shelves which is nice and toasty. Open the lid every day or two to let air in and keep the gathered droplets from raining on your cuttings. It works great for Petunias so expect it will work well for Zinnia.

Hi SouthCountryGuy,

"I am about zone 4b-5a, last frost date varies with who you talk too (I am in a micro climate) and ranges from about May 14 to May 22. "

Oddly enough, that is pretty close to my safe no-frost date. Well, it looks like your zinnia seedlings will be 6 or 7 weeks old before you can safely set them out. They will have a flower bud by that time, which you may want to pinch out to encourage branching. The zinnia seedlings in this picture (taken yesterday) were planted in the middle of March, so they have only about 3 or 4 weeks of growth, and I have already re-potted them from 3-inch pots to 5-inch pots.

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I would have to re-pot them again to 8-inch pots if I wanted to keep them safe inside until my no-frost date. So I plan to set them into the my garden before my safe no-frost date, with the idea of covering them to protect them from frost if that is about to happen. You might want to start thinking in terms of re-potting your zinnias to larger pots in order to keep them happy until you can set them out.

ZM

Hi Bacon,

"Can I plant the pinch off's and have them grow as new plants or will that not work?"

I routinely grow zinnias from cuttings, but I had to spend some trial-and-error time before I learned how to do it. For one thing, the raw wound of a zinnia cutting is susceptible to bacterial infection, leading to rot. The same thing happens to zinnia cut flowers in a vase. I use a bactericide to prevent my cuttings from rotting before they strike roots. And I use a rooting hormone and keep the zinnia cuttings under a humidity dome like Mandolls suggested. So it can be done, but it isn't nearly as easy as with many plants.

ZM

Jeepers, just stick the seeds in the ground outside when all frost is over and they will grow faster than or as fast as any you've started indoors.

All this fuss for zinnias. They grow so easily when planted directly outdoors.

Hey I'm an avid indoor seed starter, but unless you're into this pinching and rooting of zinnias for the pure pleasure of it, why go to all this trouble?

Hey Zenman,

Thanks again for the info.

For some reason I sort of panicked until I seen your plants. I should hopefully be very close to intended size by the time I plan to plant out, about 16" tall. I, too, had intended to plant out early depending on weather.

Regarding potting up I was under the impression that zinnia did not transplant well if it became root bound at all. So I ask at what size do you like to pot up? Right now I am in a 72 cell pack and my sprouts are about 3-4 days old. I had planned to move them to 36 deep cell trays today. Maybe I should just go to 5" pots.

I had wondered why cut Zinnia occasionally didn't last that long in my vases. I had considered bleaching them this year like I do rudbeckia. Now i will just use a bactericide.

I heard zinnia were easy to grow from seed just had some finicky tendencies. I am learning them :)

Thanks again.

SCG

SCG,

"Regarding potting up I was under the impression that zinnia did not transplant well if it became root bound at all."

Garden books almost always say that zinnias resent transplanting, and some sources even go so far as to say that transplanting zinnias can cause double zinnias to become single.

In the usual garden context, "transplanting" means to dig up a plant that is growing at one place in your garden and move it to a different place in your garden. Zinnias do indeed resent having that done to them, simply because zinnia root systems reach out extensively and the process of digging up a zinnia almost always causes serious pruning of its root system.

But the process of moving a zinnia from a pot into the garden, or from one pot to a bigger pot, does not need to cause any loss of the roots. I generally like to let my zinnias become slightly root-bound before I re-pot them or set them into the garden, simply because the zinnia roots can hold the root ball together and actually avoid disturbing the root system. Zinnia roots can almost form their own Jiffy Pots, with the added advantage that they don't have to penetrate a fiber pot to grow out into the surrounding medium or soil.

Of course, you can overdo anything, and if the zinnia becomes excessively root-bound, then air-pruning of the roots can occur.

"I had planned to move them to 36 deep cell trays today. Maybe I should just go to 5" pots."

If you have the 5-inch pots available and ready, go for it. I plant my zinnia seeds in 3-inch pots, so they start out "re-potted" to that size, which gives them a few weeks before they need to be re-potted to 5-inch pots. I have some 8-inch and 10-inch square pots that I can use if I have to, but they take an awful lot of ProMix, so I try to make my 5-inch pots do.

ZM

Zenman,

Gotcha, I was under the impression they didn't like to be root bound in containers. Thanks for clarifying.

In your opinion if I potted up to 3", to save room of course, would they make it 4 weeks without becoming too root bound? They are Benary's Giant(s), Uproar and State Fair.

Thanks again for all your advice. Every species seems to have its own little nuance.

SCG,

"...if I potted up to 3", to save room of course, would they make it 4 weeks without becoming too root bound?"

They would make it, but they would be more rootbound than is optimal. With 3-inch pots, three weeks is about the best time to re-pot zinnias that have big plants, like Benary's Giants, Uproar, and State Fair.

At four weeks they will have basically formed their own little Jiffy Pots, and you will need to be careful, because with such restricted root volume, they can "suck out" all of the nutrient solution in a single day. You will need to water them virtually daily, or have them in a tray that has at least a half inch of water in the bottom. Keep a sharp watch for any wilting.

ZM

Zenman *bow* thanks. It is so nice to have this kind of help even though I know you have recited it a million times.

Zinnia's have captivated me.