Does Preen work?

[SWMOgardens]

I have never tried it. I use a lot of mulch, and weed by hand. I've often wondered, will Preen stop walnut, maple, and oak seedlings? Will it affect my hostas? Does it last all year? Can I just throw it on top of the mulch? Anyone have good, or bad, results with Preen?

[Linda P]

I used Preen for a number of years on my mom's flower beds, and it certainly did make a difference.
The first year we put it on 3 times, and after that twice a year, one in early spring (when the forsythia
was in bloom) and once around the middle of July. We put it on when we established the bed, before
the mulch went down. After that, we just scattered it on top and watered it in. My mom has been gone for 7
years now, and the bed has not been kept up the last 3 years. The effect of the Preen seemed to stay
for the first year or two after I stopped maintaining the bed regularly (my brother now lives in the house),
but now it's back to the normal amount of weeds germinating.
Preen is also not much of an option for me here, though I have used it. My beds are so large, and I have
so many of them, I'd have to buy a pallet of Preen. This year I ordered some Surflan (Oryzalin) and combined
that with Round-up to spray in late March on the hosta beds. I'm not a real big fan of chemcials in general,
and try to stay mostly organic, but as I get older, it gets harder to keep it all weeded. I don't like to use
mulch, except in new beds, as I've had vole issues in the past, and don't want to give them anywhere to hide.
Also, I would need a semi=load of mulch and a couple of helpers to get it all mulched.

Linda P

[JaneG]

I use Preen early in the spring to keep as many seeds as possible from germinating, because once they've germinated the Preen doesn't have any effect on them. I sometimes remember to do it again after the wild cherry seeds fall from the tree because every darn one of them sprouts! In my beds it has reduced the number of weeds that get started in the spring.

Of course it doesn't help against the perennial weeds. And if you have an area where you want volunteer or self-seeding plants to grow, you don't want to Preen those areas.

[Chris_W]

Years ago I used it when we had a wild violet invasion and it stopped them from coming up completely after a couple treatments. Yes, you can just put it over the mulch. I'm not sure how well it works on the larger seeds like walnuts.

I'm now using surflan mixed with roundup as a spot treatment around the plants and in the open areas and pathways and find that using a liquid has a lot better results.

[viktoria]

I have used Treflan for many years and it helps (don't remember what the active ingredient is in Preen, but that brand is too expensive for a garden the size of mine). It does appear to be less effective on the seeds of woody plants, though. Ginormous flocks of starlings inoculate the garden with seeds after feeding in the hedgerows (fox grape, various viburnums, poison ivy, sumac, Virginia creeper et alii) and the number of seedlings from those does not seem to have abated. I apply the granulated form although I am told that spray is indeed more effective. This is a windy location and I want to avoid it drifting to areas where it is not needed.

Viktoria

[eastwood2007]

I'm with Viktoria on this, with the Treflan. It is much less expensive than Preen and does indeed work very well, much better than Preen in my opinion. I use the granular and just dust it over my hosta beds. You must make sure you wait until you have all your mulch down, or whatever you are going to do, as it works as a barrier. Once it is disturbed, it can allow weeds to sprout and grow there.

Not sure it is much of a threat if it blows some as it is just a seed germination preventer. I haven't seen any problems. I don't think it works on the larger seeds. In fact, I think the instructions say you can use it WHEN you are planting soy beans. I think it is considered a relatively SAFE product (if there truly is such a thing) as farmers use it with food crops.

It works on bare soil or mulch, just as long as it can make a barrier. I use it twice a year, and can reeeeeeallly tell when I don't.

I buy mine at GrassPad in the KC area. A 10lb. bag is just $12 and I can do all my hosta beds at least once with that. I just use a hand-held seed spreader to apply it. Can be done in a jiffy.

[viktoria]

Not a threat, Charla; I just don't want to waste it on areas where it is not needed.

Viktoria