Do you start zinnias from seed indoors?

donnabaskets(Zone 8a, Central MS)February 14, 2012

I have done this in the past but had a hard time getting the seedlings to gain size very fast. The last two years I waited until after the last frost and started them in six packs outside, which worked very well. But, that meant it was longer before I got blooms.

So, do you start yours inside? How early? What temperature do you keep them at for good growth? Anything else that might affect their growth rate: water? light? etc

FYI I will be growing Profusions, Zaharas, Benary Giants, and Zowies.

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Trishcuit

yes I would start indoors if you want blooms at a reasonable time frame. A shot of half strength fertilizer once a month and plenty of light and warmth. Giddy-up!

    Bookmark   February 14, 2012 at 9:26PM
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zen_man

Hi Donna,

In addition to what Trishcuit said, I do indeed start zinnias inside, because I grow some of them as an indoor gardening project. And some of my zinnias are simply started early to give them a head start when setting them into the garden. However, my indoor gardening zinnia project is in progress right now.

How early you start your zinnia seeds depends on two things: your safe no-frost date and how large you want your zinnia plants to be when you set them out. And how large you want them to be actually depends on the pot size that you intend to have them in when you do set them out.

Let's say, for the sake of argument, that you intend to grow your zinnias in 3.25-inch see-through pots. This is a picture I took today of one of my zinnia seedlings in a 3.25-inch pot, and it was planted January 25th. So it was planted 21 days ago, and as you can see from the root development, it is ready to re-pot to a larger pot, or set it out (not an option for me right now). But if this were the size of pot you planned to use, you should start your zinnias 21 days before the date you planned to set them out. Zinnias grow fast, so, as you can see, it takes them only three weeks to outgrow a 3.25-inch square pot. When they do outgrow the pot in three weeks, I either set them out, or re-pot them to a larger pot. If I should, for some reason, wait four weeks, the zinnia roots will be growing out the bottom of the pot and cause a problem in extracting them in order to re-pot the plant. I confess that I do get busy and do that from time to time.

The next size up that I use is a 5-inch square pot. Zinnias can reach the budding stage and actually bloom in a 5-inch pot. The zinnia in this pot has a flower bud and side branches beginning. Actually, a zinnia can bloom in a 3-inch pot, but that is kind of a sad thing to let happen. (Confession -- I have done that.) The zinnia in this picture (which was also taken today) is budding, and it can stay in this pot for at least 2 more weeks. It was planted on January 18th, so it is 28 days old and can stay in the 5-inch pot for at least another two weeks. If well-grown, zinnias can bloom in 5 to 6 weeks from the time you insert the seed into the growing medium. They usually come up in 2 to 4 days, although some people (not me) can get them up in one day. I set my heat mat thermostat at 80 degrees, which is 10 degrees warmer than our 70-degree room temperature. If you start your zinnias 6 weeks before your planned set-out date, they can be starting to bloom when you set them out. There are advantages to having your zinnias beginning to bloom when you set them out. One advantage is that, if you planted a mixture of colors, you can sort them according to color when you set them out. You could group the yellows together, the pinks together, the whites together, and so on. You could do that, even though the seed packet was a mixture.

This is a link to a handy planting date calculator on the Johnny's Seeds website. Just don't forget to enter your safe no-frost date, including the year, in the space provided at the top of the table. It will then use that date to give you seed planting dates for all kinds of plants, including zinnias at the bottom of the table. Incidentally, if you "go along with" the 4 weeks advance starting for zinnias that Johnny's advises, you will probably want to use a pot a little larger than the 3.25-inch square pots that I use. A 4-inch pot should be about right for a 4-week lead time. I also agree with Johnny's suggestion to wait until one week after the safe no-frost date to set your zinnias out. When I am planting zinnia seeds in-ground, I like to wait even longer than that, three or four weeks, to give the soil time to properly warm up.

If you have questions about any of this, don't hesitate to ask. I or someone else can answer your questions or clarify what I said here. If you are unsure of your "safe no-frost date", we can show you how to find that.

ZM

    Bookmark   February 14, 2012 at 9:44PM
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donnabaskets(Zone 8a, Central MS)

Hi, Zeedman. thank you for this information. The pictures are fantastic!

So are you saying that you keep the heat mats going under the seedlings the whole time they are indors? In the past, I have tried growing the plants on in my basement where the temperature tends to stay in the low to mid sixties. Too cool for good growth? I have a light set-up in the main part of my house where I could grow four flats. I can move it to my MIL's side of the house where the temperature stays at 75 or so, or in the main part of the house where we keep the temp at 68 degrees. What would you recommend?

    Bookmark   February 15, 2012 at 9:09AM
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zen_man

Hi Donna,

"So are you saying that you keep the heat mats going under the seedlings the whole time they are indoors?"

I don't have enough heat mats to do that, so when I repot them from 3.25-inch pots to 5-inch pots, they are "on their own" with just the heat from the fluorescent lights, which is better than nothing.

"In the past, I have tried growing the plants on in my basement where the temperature tends to stay in the low to mid sixties. Too cool for good growth?"

Too cool for germinating zinnia seedlings. They would germinate poorly, if at all, in the 60's. Zinnias like hot weather. Mine are also in the basement in a utility room with the hot water heater and furnace, but I keep the doors at least partly open to get some heat from the furnished area of the basement. And I have quite a few fluorescent lights, so they provide some heat when they are all lit. They are on a timer to turn them on and off for a 16-hour "daylight" period. I plan to move some of my larger plants upstairs in front of south-facing windows to get some benefit from sunlight. They will still get some fluorescent light to extend their daylength to 16 hours.

"I have a light set-up in the main part of my house where I could grow four flats. I can move it to my MIL's side of the house where the temperature stays at 75 or so, or in the main part of the house where we keep the temp at 68 degrees. What would you recommend?"

The zinnias would germinate better in the warmer area. I keep mine under a humidity dome to keep the medium moist until they emerge. Then they come out from under the humidity dome, or they will get spindly.

In the absence of a humidity dome, make sure the surface of the germinating medium doesn't dry out until the zinnias emerge. One of those little "spritzer" sprayers (like an empty Windex bottle, well rinsed out) could help with that. As the seedlings get their true leaves, they would benefit from more light if you could move them and your lights in front of a sunlit window.

If that is not convenient to do, adjust the lights to keep them about two inches from the leaves, to maximize the lighting effect.

ZM

    Bookmark   February 15, 2012 at 10:53AM
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rhizo_1 (North AL) zone 7

Donna, the zinnia don't need heat once the seed are all germinated. As you know, I sow all my seeds in dense rows and transplant them as soon as they are about an inch tall or so. But as soon as I see their little heads peeking up out of the potting medium....the plug to my heating cables is pulled.

The heat makes them spindly in a hurry. Cool temps is best for that growing on stage, especially under the less than perfect lighting situation found inside.

    Bookmark   February 15, 2012 at 10:22PM
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donnabaskets(Zone 8a, Central MS)

Thanks, you two! If memory serves correctly it was germination that was my biggest problem in the past. I am sure I can get them enough heat to germinate, especially now that I know I can plant them densely at first. Once I separate the seedlings and put them in individual pots I will send them to the basement to see how they do. I am so excited to learn something that will make my seed starting even better!

It is about 7 weeks until my frost free date. On the Hazzard's website, with regard to Profusions, it says "seed to sale in 7 weeks". I assume this means until blooms. Do you think that four inch pots will be large enough for a 7 week lead time or should I wait two or three more weeks to get started?

This is all such a great help! I cannot tell you how much I appreciate both of your generous sharing of your knowledge and experience.

By the way, if anyone else is watching this thread, I am going to include a link to a thread over in the Vegetable Gardening Forum. Read it all the way down and you will find some very valuable info on seed starting. Watch the "Tomato Man" video that is linked there, too.

Here is a link that might be useful: Read this and learn!

    Bookmark   February 15, 2012 at 11:24PM
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zen_man

Hi Donna,

I read your linked thread with interest. I have several pots with multiple seedlings in them right now, because I planted some old seeds that had a low germination rate with as many as 9 seeds per pot. Some pots produced only one seedling from that (a few got none), but several got two or three or even four germinations. I think I will try to "re-pot" them into separate pots. I think that is a skill I need to learn. I have in past years had some success in letting zinnias grow to first bloom in that situation, and cull all but the best bloom by snipping off the rejects at the soil line, but that does "stunt" the remaining plants.

However, in the past I didn't mind doing that so much, because I do cull aggressively in order to get significant improvements in my zinnias. When I am hand pollinating my zinnias, I want to be making crosses between only "the best of the best". Knowing that I will be keeping only the best specimens at bloom time, I do set them out or sow them in-ground closer together than I would normally, knowing that I will be opening up spaces when I remove the rejects. In some cases, that leaves quite a bit of open space, but that can be a benefit to the remaining plants, like last year in the case of this spreading zinnia. This was a single plant.

That specimen was a hybrid of hybrids and seemed to be a mutation of some sort. The plant seemed to be a shrub and it spread across the ground, eventually producing dozens and dozens of blooms. I never saw anything like it before, so I designated it as a "breeder" and crossed it with other unusual specimens and selfed it as much as possible, although it produced very little pollen of its own. There are species of zinnias that are true shrubs, but this was garden variety Zinnia elegans (now referred to in academic circles as Z. violacea). I have no idea whether its unusual plant habit was an environmental response, or genetic. Perhaps this year I will know as I grow some of its progeny.

"Do you think that four inch pots will be large enough for a 7 week lead time or should I wait two or three more weeks to get started?"

I usually have my seedlings in 5-inch pots by 7 weeks. Also, following Johnny's Seeds advice to set them in-ground one week after the safe no frost date, that would be 8 weeks from now. I think you should wait two or three more weeks to actually plant the seeds, but in the meantime, you could do some preparatory work. If your pots and trays have been used, as all of mine are, you will want to wash them. I never cease to be amazed at how much time I spend washing pots and trays.

And I have a couple of fluorescent fixtures that have "died" and need to have new ballasts installed. I have several extra ballasts on-hand for just this situation, but it takes me an hour or so to refurbish a fluorescent fixture. Indoor gardening can be busy, busy.

ZM

    Bookmark   February 16, 2012 at 10:44AM
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mxk3(Zone 6 SE MI)

Informative seedling pics, Zen - thanks! :0)

    Bookmark   February 16, 2012 at 11:36AM
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donnabaskets(Zone 8a, Central MS)

You are so right about the time required to wash pots. Oh well, nothing in life is free. I will wait a couple more weeks before I get started with the seeds. Thank you for this valuable timing advice.

That is quite a zinnia there in that picture! It rather reminds me of a large sized Profusion in its habit. Very interesting and would be great in a border, not needing to be staked. I hope you can do something with it.

Isn't it fun to learn a new skill? I can tell you that I have read prodigiously on gardening for twenty years or more, and I don't recall ever reading anything about this re-potting technique until here on the Forums. The combined skill set of our members is truly a treasure.

    Bookmark   February 16, 2012 at 11:36AM
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rhizo_1 (North AL) zone 7

Donna, do you not use heat mats or buried cables for your potting medium? I guess, if you are sowing directly into cell packs, you'd need to use heat mats. If you grow lots of plants, that could be expensive. By using flats for germination, you'd cut back drastically on the space that required soil heating. My cable has an in-line thermostat that maintains the soil temperature at around 75F. I'll just be using two flats (trays) and plan on germinating about 600 or so plants this year. Zinnias will all germinate in a couple of days, if not overnight.

Here's my time saving tip for cleaning those pots, trays, and cell packs. At least, I 'think' it saves time, lol. The minute I am finished with any piece, it gets rinsed out with a strong spray of water so that no potting medium remains. An easy task since they are still moist. After air/sun drying, they get stacked and put away. I never wait to do them all at once. Don't forget that UV waves are great for sterilization of surfaces!

At the beginning of a new propagating season, I simply fill my kitchen sink with a 10% bleach/water solution (or stronger) and bring in the stacks of everything for a short soaking. I've also done this outside in a large plastic storage container. I also soak any small tools and utensils I may use at this time, too. No washing or scrubbing required since everything was sprayed clean immediately after using.

I've learned through experience to store everything in heavy duty plastic bags for the winter. Black widow spiders have a VERY strong affinity for stacked containers of any kind. Just saying....

    Bookmark   February 16, 2012 at 12:54PM
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donnabaskets(Zone 8a, Central MS)

Great tips, rhizo! I have done the soaking thing before and had great success with it, but was afraid to say so on GW for fear that it's "wrong". I need to be more disciplined to do the strong rinse out at the time of transplanting.

I have always sown my seeds into cells. I do have a couple of heat mats which I usually reserve for seeds that I know need pretty high heat. But the last two years I have been using the "hot spots" in my home for germination. I have one set of commercial Light stands that holds four flats at a time. It's fairly easy to move around. My mother in law lives with us and keeps her bedroom and hall at 75 degrees or more, so I have the light stand in there right now. When I started eggplants and peppers last year I took the stand into a small extra bathroom we have and set up a small space heater in there, and just kept the room at eighty degrees for a couple of days. Pretty low tech, but it worked.

BUT, now that I know that I can sow so many plants into a tray at one time, and that it's actually to their advantage to do so, that is how I will finish up my seed starting! That one heat mat will got alot further now!

In the end, I seriously doubt I will spend anymore time doing it this way than I would have meticulously sowing one seed at a time into all those cells and then having to re-sow the skips. And then, I have plenty of room for all of them to grow on down in the cooler basement.

How on earth did people learn these skills before the internet?....

    Bookmark   February 16, 2012 at 7:42PM
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donnabaskets(Zone 8a, Central MS)

Just an update to this thread. I started my zinnias five weeks ago and they are getting ready to bloom. Thanks to both of you for your help. I have had the best looking seedlings this year EVER. I started setting them out into the garden this past week. We had a good rain the day after and they all put on noticeable growth. I ended up using a blend of Uproar Rose Zinnias, Cramer's Burgundy Celosis, Purple Passion Cuphea and rose colored Cleome in the background areas of my perennial bed. Along the front edge I used yellow Profusion zinnias mised with Lavender Vinca and Evolution Salvias. Also mixed in some Cuban Gold Durantas for a pop of chartreuse. I think it will be a beautiful bed this year.

This next week I will plant my driveway beds with a mix of Yellow Profusions, Fire Profusions and the new Scarlet Zahara Zinnias backed with Zowie Flames and Mystic Spires Salvia. If I can get these out this week I will have knocked out about eighty percent of the dozen or so flats of flowers I started.

All the tomatoes are in the ground and going like gangbusters. I do so love spring!
Thanks to you both for all your help!

    Bookmark   April 8, 2012 at 8:39PM
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rhizo_1 (North AL) zone 7

Sounds GREAT!

    Bookmark   April 8, 2012 at 9:59PM
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mxk3(Zone 6 SE MI)

I sowed my seeds indoors two days ago and many of them have germinated already!

    Bookmark   April 9, 2012 at 9:38AM
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donnabaskets(Zone 8a, Central MS)

Amazing things, seeds. I never get tired of the process.

    Bookmark   April 10, 2012 at 8:11PM
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ladyrose65

Wow! I can't believe the spread on that 1 zinnia plant.

    Bookmark   April 30, 2012 at 9:37PM
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zen_man

Hi Rose,

That "shrub zinnia" was possibly the most unusual zinnia I have grown. After a couple of killing freezes, I was cleaning up the garden, removing all the dead zinnias and putting them in big black plastic bags for our trash pickup, and I got to see the "skeleton" of the shrub zinnia without the cover of live leaves.

Exposed like that, the structure of the plant looked almost vine-like. Its side branches seemed to grow in an indeterminate fashion, like the difference between indeterminate tomatoes and determinate tomatoes. By the time they had grown a couple of feet, the side branches could no longer support themselves as cantilever structures and they drooped and rested on the ground and continued to grow, all the while putting out side branches of their own.

In several places the vining branches had struck roots into the soil they were resting on. The structure of the plant reminded me a bit of Bermuda Grass, a plant that I am not fond of. I will be growing its progeny out of curiosity, but I have to admit that I am ambivalent about it. And I am still uncertain whether its unusual structure was genetic, or a response to some unusual environmental factor.

This should be an interesting zinnia year for me, because I am growing several crosses involving unusual parent specimens. Crossing mutants with other mutants can produce some odd stuff. Hopefully some of it good.

ZM

    Bookmark   May 1, 2012 at 12:20AM
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golfcole

How do you keep your zinnias so compact? I've had stretchy plants and am wondering if I've given them too much P or if my temp is causing the stretch

    Bookmark   April 23, 2013 at 10:45PM
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zen_man

Hi golfcole,

"How do you keep your zinnias so compact?"

I think the most important thing is to give them enough light. That means keep the fluorescent lights within a few inches of them. And I have my timers set to give them very long "days", with 18 hours of light and 6 hours of dark. This time of year the sun is higher in the sky and you probably won't get any significant amount of direct sunlight through a window, so just concentrate on keeping the fluorescent tubes close to them.

Nutrition-wise, use a balanced formula, fairly dilute. I give them an initial dose of Better-Gro Orchid Plus, one teaspoon per gallon. Then I switch to one-quarter teaspoon per gallon for maintenance. When they start to bud out, I blend Better-Gro Orchid Plus with Better-Gro Orchid Blooming formula, which has a higher percentage of Phosphorous. Zinnias are heavy feeders, and in containers you can expect to have to feed them every two or three days. Be on the lookout for deficiency symptoms. You might need to add some soluble Calcium, like Calcium nitrate, if your water supply doesn't contain some soluble Calcium. My Premier ProMix has a little Calcium in it, but only enough for about three weeks of zinnia growth.

Also, be on the lookout for Boron deficiency symptoms. Good complete nutrient formulas contain some Boron, but apparently zinnias like twice as much Boron as orchids. I use a little Boric Acid powder purchased from a drugstore. I make a stock solution of one-quarter teaspoon Boric Acid per gallon, and add one cup of that stock solution to each gallon of complete nutrients for the initial treatment and half a cup per gallon for maintenance.

Boric acid powder dissolves very slowly in cold water, so I heat a cup of water in the microwave, pour that in an empty water bottle, add the quarter teaspoon of Boric acid powder to the hot water, swish it around until it dissolves, and add that to the gallon jug and fill it up to create a gallon of stock Boric acid solution. Discard the water bottle. You don't want to drink any of the Boric acid.

Some water supplies have plenty of Boron and Calcium in the water, so it can be helpful to have access to an analysis sheet for your water. I have to add both to our well water.

ZM

This post was edited by zenman on Wed, Apr 24, 13 at 1:39

    Bookmark   April 24, 2013 at 1:26AM
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zen_man

Hi golfcole,

(this duplicate deleted)

ZM

This post was edited by zenman on Wed, Apr 24, 13 at 1:37

    Bookmark   April 24, 2013 at 1:27AM
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zen_man

Yikes!! Some kind of communication glitch created a duplicate of that message. I think I will try to edit away the duplicate.

ZM

This post was edited by zenman on Wed, Apr 24, 13 at 1:34

    Bookmark   April 24, 2013 at 1:29AM
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golfcole

Awesome I'll give that a try and see what I come up with. Thanks alot

    Bookmark   April 25, 2013 at 7:51PM
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suzen221

Hi everyone, was reading old post about zinnia's indoors. I found that using a 20$ lamp and the spiral bulbs help thingds grow faster. Am bnow trying it with zinnia's buut im going to wait till febuary to try this

    Bookmark   January 20, 2015 at 2:59PM
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