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When to start my Zinnias

Posted by lady_alicia 5 ( on
Thu, Jan 6, 11 at 23:27

I'm trying to figure out when to sow my Zinnias indoors. I start most of my seeds indoors (never did Zinnias yet) from February and on. I'm in Zone 5 and usually plant outside later in May to be safe.

I've read that starting Zinnias should be 3 to 4 weeks prior to my last frost date. It doesn't seem like they would be very tall to plant outside if germination takes a week or so. ??

What would you recommend I do? Sow them in March? April?

I've found that lately when I direct sow my Zinnia mixes, I don't get a good germination rate, bugs eat the new leaves, etc. So I was hoping by starting them inside I could actually have some Zinnias this year! :) They're my favorite annual flower and I'm trying a bunch of specific varieties, so I need a little help.

I have read a lot of the other posts, but there's a lot to sift through, and this was one question I still had that didn't get answered by reading them. :)

Thanks in advance.

Follow-Up Postings:

RE: When to start my Zinnias

  • Posted by zenman Ottawa, KS 5b (My Page) on
    Fri, Jan 7, 11 at 1:31


This would probably be much too early to start zinnias indoors in Zone 5. I have actually had some zinnias start to bloom indoors in 5 weeks from their sowing date. I start my fancier zinnias indoors to get them beyond the cutworm susceptibility stage before I set them in the garden. I start those zinnias in 3-inch square pots. I plant one seed per pot or thin to one seedling per pot.

In two or three weeks I re-pot them in 5-inch square pots, where they can mature enough to be immune from cutworm damage.

I direct sow the majority of my zinnias and take some losses from cutworms, slugs, snails, and other critters. A Bt spray will get some of the small roving cutworms.


RE: When to start my Zinnias

According to my records, I sow zinnias indoors under lights on 3/31.
I use diluted fish emulsion when they have their true leaves.
I grow large zinnias such as 'uproar rose' and 'giant wine'
and have them in quart size containers by the time they go outside end of May(hardened off,of course).
I grew two different Zahara zinnias last year and I think they were a good size when I put them in the ground.

RE: When to start my Zinnias

Very helpful information. Thank you, both!

Zenman - You spiked my curiosity with your labeling system. What is the C6, TOM, PEP and the various numbers all mean? I log things in my books on when I sow my seeds and their germ. date, but I was curious as to how you organize/categorize your plantings/seedlings.

People think I'm so organized and experienced, but if they only saw and read what all of you! :)


RE: When to start my Zinnias

Alicia, please note that zenman has a lighting system set up for his seedlings. This is important if you are going to grow quality plants inside.

I agree with the others....between 4 to 6 weeks is more than enough time to produce stocky little plants. (The smaller your seedling containers are, the sooner they will need to go into the ground.) They're fast little things, believe me.

I use cell packs and liner trays for the most part. I have some that are 18 to the sheet and others that are 24.

RE: When to start my Zinnias

Yeah, I have the lights, heating mats and everything already. I grew about 100 different tomato plants last year and 50 'Red Elite' Geraniums and numerous other flowers/plants. :) Overall, they did well. I ended up giving a lot of the tomato plants away. I didn't think they'd do as well as they did. :)

The only thing I will do differently this year is not use the plugs in a couple of the seed-starting supplies I have. I did not like those at all. I got very long, stringy roots. I transplanted them, of course, once they got so big, but I felt they were pricey for what they produced as far as plants. I have pictures of the ones I started in dirt and the ones I started in the plugs, and the plugs had MUCH smaller plants. And they were the same type, same sow date, same light, etc. This year I'll use plain old seed-starting mix in the holes where the plugs go. And then I also use flats, cell packs, homemade newspaper pots and other misc. pots for starting seeds. I'm also buying two more stands with lights on each shelf this weekend, which will give me eight more shelves of growing!

I'll go off of the 4-6 weeks with the Zinnias, then. I just wanted to be certain I was going to have nice, sturdy plants to plant outside and wasn't sure of timing. You read so many things online, so it's always nice to see what others actually have done.

I do have a hardening off system also. :) I have a baker's rack outside that I took two clear shower liners and attached them together and place over it. Then I put my flowers in pots on the baker's rack for the summer. It works out well also. I just need to create something else until my husband builds me my small greenhouse. :)

How do you harden off your plants??

Thanks for your advice!

Inserting link to view a few pics I took last year of my seed-sowing and the long root on the one plug, etc. I didn't want to insert them in the post because my pics are too large for viewing that way.


Here is a link that might be useful: Seed-starting pics

RE: When to start my Zinnias

  • Posted by zenman Ottawa, KS 5b (My Page) on
    Fri, Jan 7, 11 at 13:21


"You spiked my curiosity with your labeling system. What is the C6, TOM, PEP and the various numbers all mean? I log things in my books on when I sow my seeds and their germ. date, but I was curious as to how you organize/categorize your plantings/seedlings."

Since I use small plastic labels, there isn't a lot of room on the label for a lengthy description, so I use short codes. I did a stint in the military, so I adopted the military/European convention for recording dates in the dd/mm/yy format, with just a "dot" separating the fields. TOM stands for tomato, PEP stands for pepper, and my zinnias get a letter-number code.

C6 was the 6th designated breeder specimen in the year "C", which was 2009. I actually started numbering my selected breeder zinnias in 2006 as 1,2,3,.. but by the end of the year realized that plain numbers were going to become unwieldy, so in 2007 I added the prefix "A" to all of my breeder codes in that year, with B for 2008, C for 2009, and D for 2010. All of my breeder specimens designated in 2011 will have a prefix of "E".

I keep a journal that records more detailed descriptions for each code. All of the seedlings with a C6 label were seeds from the specimen designated as C6. Only a few of those seedlings turned out well enough to be selected as breeders in 2010, with codes beginning with a "D". My journal entries make note of the female parent, so I have a maternal "blood-line" family tree for my zinnias. In many cases the male zinnia parent is not known. When it is, I make note of it in the journal.

In a truly scientific breeding program, both parents would be recorded to produce a complete genealogy, but even when I isolate a breeder seedhead with a "hairnet", I select pollen for it based on breeding objectives. For example, a spider flowered female would be pollinated with other spider flowered specimens or possibly with selfed pollen or possibly with interesting out-crosses like a good bi-colored specimen or some other likely-seeming cross.

Since zinnias are Composites, each petal is botanically a "flower" all by itself, and you could pollinate the stigma on each petal with different male pollen, if you were inclined to keep records at the petal-individual-seed level. Even if you were motivated to do that, it would be very difficult to devise a labeling system for individual zinnia petals. I do my zinnia breeding for fun, so I pretty much "take the path of least resistance".


RE: When to start my Zinnias

ZM - I'm so impressed with all that you do! It truly inspires me. I would have to do a lot of research and ask a gazillion questions, but perhaps I will try to breed my own specimen someday. It sounds like you do quite well with that. And I really am quite serious in doing it because my brother and his wife just lost their baby before Christmas, and I would love to grow and name a flower after her, even if it's just for us to grow; not so much for registry. I looked into naming a flower after someone, and it's thousands of dollars, so forget that. :) But my family counts on me for growing them flowers, doing their landscaping, planting advice, so I thought that would be something very special that I could do for them.

Well, I appreciate all the guidance you've offered, and I prefer your labeling system over mine. :) I have a chart that I record things on that I print out each spring, and then I just label each pot or grouping, but it's hard to fit it all on the plant marker, so I find that your method would be much better.

Happy planting!

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