Hi Cindi,

As you may know, I grow a lot of zinnias here in this part of East Central rural Kansas, and I make a significant investment in improving the soil in my two outdoor gardens. Our native soil is a dark heavy sedimentary type. I add sand to our dark sedimentary garden soil as an amendment. Since my two gardens total more than half an acre, I use a lot of sand, so I purchase washed river sand a truckload at a time. That gives me a big sand pile that can last for two or three years.

I have a tiller, and I use it to routinely mix the sand into the existing soil before I make a planting. Eventually the garden soil approaches a sandy loam, whose porosity has the advantage of getting lots of oxygen to my zinnia roots. I also apply a sand mulch around my growing zinnias.

ZM

first.. have a soil test done.. to define your soil ... and then determine if you need any amendments at all ..

and then you ight do a perk test.. to understand how your soil drains ...

properly done.. a gardener doesnt just amend willy nilly for no good reason ...

and to be clear.. we are taking amending.. not top coating of humus ... or organic material ... correct???

if you can define in words what your soil i like.. we might discuss what might help it ... and your big city location never hurts ... maybe a pic or two ...

ken

ps: zen uses sand.. because his experience determined it helps.. in my yellow sand... adding sand would be like adding water to the ocean.. to make it wetter.. lol ... we really need to have an idea of what you have to start with ... and BTW ... Zs do just fine in my sand .. but i dont grow them to perfection like zen does ... but i have to water very often in the heat of summer ....

Thank you Zen Man and Ken.

I live in NC. We have clay soil and I think I live on a rock. lol I guess I am more talking about maybe top coating. The only thing I have been doing is adding compost, and leaf mold when planting.

The overall is that zinnias grow well on "fertile, well-drained soils high in organic matter."

That's kind of general. But pretty much, feed well, they prefer damp over wet, and mulch them. They'll be thrilled. :-) In my average Pennsylvania garden, they look great. I feed a lot, and once established, they're pretty tolerant plants.

Tru dat. I'm a "pack it in" gardener and I did have to learn to take a breath in terms of the zinna. Too close, they get powdery mildew from the closeness (humans should take a lesson and social distance...)

Use the recommended distance...or even a bit more if you feed well like I do. Those Magellan zinnia, well-fed, will exceed their natural potential and go wide and tall.

That's actually another thing about zinnia. They don't object to a good feeding. Regularly. Keep it coming. They're not particular about it and won't do badly if you don't, but they outdo themselves if you do.

Oh, and feel free to cut flowers. They'll just divide the stem and grow four more in place of the one you cut.

I think I live on a rock.

==>>> yeah.. that would be a problem ... lol ..

have you perked you clay soil ... clay is usually very high in nutrients ... the issue is drainage ...

https://duckduckgo.com/?t=ffnt&q=perking+garden+soil&ia=web

if you have very bad drainage... youre better off building a good bed of soil on top ... and that is where you start your quest ... you do NOT amend only planting holes.. as it accomplishes little if nothing.. and often makes it worse ...

the other problem with your rock.. might be soil depth ... is that an issue ... its another reason to build up the garden bed ... the slow motion way to do that.. would be adding compost on top ..... year after year .. but there are ways to speed that up ...

how simple your original question was ... lol .. i bet you were hoping for a simple answer ...

ken

Of course I wanted a simple answer, lol. I have been adding organic material over the years and my soil has gotten better.

I think the reason I was even wondering what to use is- (here comes the stupid part)

There is a certain variety of zinnias that I plan on growing this year - Unicorn zinnias. I had read that someone said that to get the pretty double ones, there were certain nutrients that you need.

They did not know which nutrients, and it got me to wondering what nutrients were needed for good zinnia production.

The zinnias I grow do very well in my soil, but could they be better if I added different amendments? Just trying to help my flowers anyway I can.

CP

Oh, those are lovely zinnias! I can't find anything about special requirements online (and I grow other double zinnias here without any issues), and I'm not zen man, but I can at least tell you what I do until he stops by...

Soil type doesn't matter too much, zinnia aren't particular. Mulching is nice, it moderates out the water in the soil, but isn't strictly necessary.

If you know your soil resources (from a yearly soil test), you already know if you need more phosphorus and potassium added when you feed. I, personally, don't need anything but a whisper of P to replace what slowly leaches and a small amount of K. So in my case, I make my own fertilizer, but your mileage is almost certainly going to vary and that's OK.

If you're not sure, one or two once yearly early in the season application of something like 10-10-10 won't go amiss in the flower bed. Flowers tend to be heavy users of P and K, and when you cut flowers and, at the end of the season, remove the greenery, you're carrying that away. I'd get that soil test and verify that it's OK after a couple of blind uses, though.

We can argue phosphorus levels all day in gardens. For flowers, they actually should be on the upper end.

That P won't move in fast, but it'll get there eventually. Probably the second or third year. :-) The K moves much faster.

If you know the pH of your garden is in proper range, that takes care of calcium levels (and hopefully magnesium levels). But again, only a good soil test can tell you for certain.

After that, I've found zinnia (and a lot of other things) tend to peter out if you don't keep up the feeding. In my gardens, I feed at a rate of about 1/4 pound of nitrogen per thousand square feet through my irrigation system per week. If you were using Miracle Gro, it's as if you used a quarter of a feeding, except it has just a tiny trickle of anything except nitrogen.

Once a month, I spread an organic on everything--gardens, pots, you name it. Usually that's a bag of Milorganite or a bag of soybean meal, so at about 16 to 25 pounds per thousand square feet, just to add to the mix. That's not strictly necessary, though!

And really, those are the heavy-hitters. While some of the micro-elements in a garden might be short, again, only a soil test would tell you.

morpheuspa, Thanks so much for the information. Most of the time I use Miracle Gro Bloom Booster on my zinnias, but I think this year I will work in some 10-10-10 when I am working the soil, before I sow my seeds.

And I do need to get my soil tested.

CP

Bloom booster would be just fine and there's no need to get anything special. :-) Seriously, when I say these aren't particular plants, they aren't particular plants. And there's definitely no need to work anything in. If you've been feeding through the years, the soil is certainly rich enough for undemanding zinnia.

10-52-10 is really high in P, so I'd use regular Miracle Gro (high N, lower P, middling K) most of the time, but as a once a year boost, no problem until the soil test. With the regular Miracle Gro (what I used until I started making my own 26-2-4 equivalent), it'll average out over the season well enough.

If you're sensing that I kind of wing it and do the math as I go, you're right. As long as the numbers work out, brackets stay within norms on soil tests, and the plants bloom like gangbusters, I'm thrilled.

I love zinnias but never heard of Unicorn, so I googled.... I should have known that Floret had something to do with them! I want to live on her website. It's gorgeous. And as someone who used to sell bouquets at market and had to give it up, I am envious of her and live through her vicariously lol.

Sorry, other than that statement I don't have much to add to the above conversation lol. I just wanted to say how lovely those zinnias were - and of course, wish you good luck in growing them! Be sure to post pictures this summer!

:)
Dee

Thank you morpheuspa and winging it is all I ever do. lol

Dee, Aren't those zinnias beautiful? If you go to Instagram and look up unicornzinnia and unicornzinnias, people have posted photos of their unicorn zinnias. I hope mine look as pretty as theirs.

I'm in OK z7 and DH grows zinnias successfully in full sun and I can tell you right now he adds nothing to the soil and doesn't fertilize.

I grew some a few times with success and I didn't do anything but water. You can tell if the soil is good just by looking at it, IMO. If it's too hard, add some all purpose potting soil which is what I do when I hit a spot of clay.

I'm in a rural area where it's pretty hard to test the soil. Just do a lot of online research and good luck!

Thank you Oakley. I have grown them for years, but there is a variety that I want to grow and I have heard that it needs certain amendments, I just do not know which ones.

I feed with Osmocote (slow-release) once at planting time and that's it. No soil amending. I have never found zinnias fussy about that sort of thing.

do zinnias grow better in soil from ground, composed, or store bought?

If you are planting them in the ground, then the indigenous/existing soil is what is needed. 'Store bought' soil is for filling raised beds or for containers. Period. Compost is only a soil amendment, not a stand alone planting medium on its own.

There is a lot of rather specious info that as been posted here over the years. A lot of demonstrated misunderstanding of fertilizers and how they are accessed or used by the plants. So-called 'bloom booster' fertilizers are a waste of money. High P or K numbers are unnecessary as these nutrients tend to be present in the soil in adequate levels anyway and excess P in particular poses water pollution issues. Plants of all types access needed nutrients in a 3:1:2 ratio regardless of where they are in the bloom cycle. Miracle Gro, Dyna Grow and several formulations of Osmocote offer these in this ratio and will work perfectly well for fertilizing any annuals, vegetables and the vast majority of houseplants and perennials. Trees and shrubs rarely require any fertilizer supplementation.

Finally, one cultivar of zinnia does not require any more specific plant nutrients than does any other cultivar