If you cut off the spent flowers heards before they form seed there won't be any seed to fall. This is of course a lot of work but if you really don't want the plant to reseed that's what you have to do or else remove the plant altogether.
Joann

In my pre-organic gardening days I used Preen and it did work well. If you're not an organic gardener and don't mind chemicals, try Preen. Now I try to stick pretty much to organic but have the same problems with reseeding as you are having. I've done cardboard which works well but does make planting tricky sometimes. Laying that cardboard and covering around existing perennials is also a LOT of work. I do use some cardboard every year but never get all areas.

Last year I tried corn gluten in spring and fall with no effect at all. I'm going to have to eliminate some types of flowers totally or almost totally as I see no other alternatives. After walking through my yard yesterday larkspur and nigella top the list. I just can't deadhead and weed that much.

My soil just seems too fertile. We apply a good 3" of wood mulch each spring. (Have tried both large and small bark chips, shredded bark, pine fines, makes no difference). I usually apply leaf mulch every fall too, but didn't get all finished this year. What areas I did do leaves blew away anyway. I took pictures yesterday which I haven't downloaded yet.

Karen

yes, I am now going to not plant those that re-seed too generously.

Karen wrote, "My soil just seems too fertile."

This made me laugh. :) I wish I had this problem. I'll trade you some of my dried-up, cement-like clay for your too fertile soil. I guarantee I can take care of your reseeding problem with a little of my magical, growth-inhibiting Wisconsin clay. I'll even throw in some rocks for top dressing. :)

(Eleven years and counting of organic amendments. I am increasing tilth one square foot at a time.)

cheers,
Norabelle

Lots of wood mulch seems to work for me. I rarley get re-seeds.

Karen

Norabelle, only difference is Ohio clay, organic ammendments, mostly compost, for nearly 25 years. See pictures I posted in other thread.

Here is a link that might be useful: weeds

Okay, so at 12 years and counting, I only have 13 more to go. Woohoo! :)

Can't complain, though. I've got plenty of areas of our yard that have become quite healthy and fertile; I just keep reclaiming a few square feet every year. Amazing to see the difference just a few feet makes in the garden where amendments have been placed for a longer period of time.

cheers,
Norabelle

Norabelle. I have the rock hard stuff too! I have been adding compost and dirt and the beds are better. Once I added stuff the worms liked they also helped me a lot! I love those little poop machines. they do a lot of fertlizing and natures way of softening hard soil :)

I add lots of stuff when I can. Especially to the veggie areas. Last year I added so much I had lots of baby worms everywhere. I could not even dig that are without scooping them up.
Karen

For years I mulched my beds thickly with shredded leaf mulch and rarely had any reseeding. Didn't even think about it as it just didn't happen. Where I want reseeding I have learned to remove the mulch.

I don't use any mulch (too many beds, saving for a shredder and then I will)just some top dressing of compost and I find the only way to deal with copious reseeding is to decide where I do want some volunteers (and I do love some of them - free plants!) and then mow down the extranious volunteers with a hoe when they are tiny baby sprouts.Of course it takes some experience to identify that the little sprout coming up is that reseeding X that you are trying to control....... each year knowledge of your garden gets deeper and the next year builds on it.

My nickname around here is the 'Deadhead Queen' and that is what saves me from re-seeding. I go out every day and deadhead everything - it's part of my daily ritual in the garden. I keep a keen eye on Four O'Clocks and collect the seeds - I can see them as they form and I collect them before they drop. I reserve save a few blooms for seed collection and save them, but in the fall, I cut off every flower, every seed pod and I cultivate the area around the plants. I did not set out to do this, but when I realized that all my 're-seeding' annuals were not re-seeding, I figured it out. When I worked, I did my 'walk about'right after work - just took off my shoes. Now I do it first thing in the morning with my coffee mug in one hand. It's not as much work as it seems - it's my quiet time in the garden which is how I retain my sanity.