I've done this before. I waited a week after spraying to plant, but I don't know if you have to even wait that long. I know it can be hard waiting to plant things out in a new bed, but it's probably better to be safe than sorry and wait the week.
Good luck with the new bed,
Laurie

I'd wait to plant for a couple of weeks or more, sometimes you have to give RoundUp a second application for those tough weeds or for the weed seeds that haven't emerged yet. It's a good idea to not be too much in a rush to plant right away without getting all the weeds under control first, otherwise you'll have a never ending war down the road ;)

Sharon

Thank you for the advice. A couple of weeks isn't bad, I thought I'd have to wait a couple of months. The weeds seem to be extra bad this year.

True, if you have any thistle in there, you'll want to repeat the application. If you have lots of wild oats, I'd wait a couple of years to clean it out! I made one bed that had been part of a field for years and the wild oats were so bad it took me 3 years before I finally got it under control. I found out later that those seeds can stay dormant in the ground for up to 20 years! So, if you can identify the weeds you have that can help your decision as to when you should plant.
Laurie

I did the same thing a few years ago and repeated applications for a whole summer (the real reason was I was too lazy to plant anything in it tee hee). Anyway, the thistles were the first thing that always came back, followed by buckwheat. It's not too bad to weed a few things by hand if you stay on top of it.

angelao, Round-up and similar products containing glyphosate have no effect on the soil. You could spray it on bare dirt and plant immediately with no harm to your new plants. The chemical is only effective when it hits green, growing tissue (so it's more useful in the spring than in the fall). The plant then translocates the glyphosate to the roots and the weed is dead (theoretically--I've recently read that some plants are developing a resistance to the chemical if they are not completely killed with the first application; that's similar to bacteria becoming resistant to antibiotics, but I digress...) It's extremely important that you don't get any of the chemical on the green parts of any desirable plants. (So be careful if it's windy.)

The reason you would wait before planting is, as other posters have mentioned, to give time for other weed seeds to germinate so you can get rid of them more easily than if you had a bed full of your chosen plants.

Here's a way you can have your new flower bed more quickly, without stirring up any new weed seeds: Spray your existing weeds with Roundup and give them a little while to die (insert evil laugh here). Cover your bed with a couple of layers of damp newspaper (dry newspaper would blow away...and wet paper decomposes more quickly), top that with several inches of good garden loam, or compost, or triple-mix, or all three, and then plant. Voila! Unless there are weed seeds in your loam, you're off to the races. Anyway, that's just a suggestion. Search the archives (or Google) for more information on Lasagna Gardening.

Doris

Hi Doris,

Actually my new garden bed is a lasagna garden. I'm already seeing some grass growing through - I hope it originates from the top layer of soil and not already coming through the newspapers. My layers of newspapers were at minimum 15 sheets thick.

Henry, in her flowerbed she is not planting tomatoes. I live next to farmers' fields. When they spray any chemicals on their fields I have noticed damage only to my tomato leaves, nothing else in the garden, not to any other annuals or perennials.

They do say that when a plant dies from being killed by roundup that some give off a chemical themselves as their roots die that will affect the newly planted plant. I don't know which ones do so.

There are 2 different kinds of roundup, regular and transorb. Regular roundup you cannot get the plant wet with rain for a certain number of days, I think 3, but I use transorb and there it takes effect basically immediately. I wouldn't have any problem in spraying transorb roundup, waiting 2 days, pull out the weeds that were sprayed, mixing up the soil and adding compost or whatever, and planting up the flowerbed all in the same week. Some posters talked about annual weed seeds sprouting. If you mulch over the flowerbed after planting, you do not have to worry about them.

You mentioned that you had grass coming up already. This means that you either missed it with the roundup the first time or you got it with regular roundup and you had rain or moisture to "wash" it off the grass before the roundup had a chance to work. I have had that happen, so...spray again, or if you have already planted your perennials in the flowerbed in and amongst the grass get your q-tip out and start painting your grass with roundup. It takes time but it's worth having a grass free flowerbed.

Title: Initial and residual activity of glyphosate and SC-0224 in a sandy soil.

Authors: Devlin, Robert M.; Karczmarczyk, Stanislaw J.; Zbiec, Irena I.; Koszanski, Zdzislaw K.
Authors affiliation: Lab. Exp. Biol., Univ. Massachusetts, East Wareham, MA, USA.

Published in: Crop Protection, volumn 5, pages 293-296, (1986).

Abstract: "Initial and residual herbicide activity of glyphosate [1071-83-6] and SC-0224 (trimethylsulfonium carboxymethylaminomethylphosphonate) [81591-81-3] when applied to a sandy soil was investigated. A bioassay employing wheat (Triticum vulgare cv Mericopa) was used to det. the residual activity of the herbicides on different characteristics of plant growth. At 5 kg/ha, both herbicides significantly reduced shoot length. This was obsd. in wheat planted immediately as well as 10 days after application. SC-0224 was more active than glyphosate, significantly reducing shoot length at the 2.5 kg/ha rate 10 days after application. Root length was reduced by both herbicides at 2.5 and 5 kg/ha in wheat planted 10 days after application. Redns. in fresh and dry wt. were also obsd. for both shoots and roots. Thus, SC-0224 and glyphosate have residual herbicide activity in sandy soil, at least £10 days after application, and SC-0224 has more herbicidal activity than glyphosate in this respect."

Sandy soils? Most folks on the Canadian praries can only wish for sandy soil. Think heavy gumbo clay with a high PH.
Jan

Title: Influence of soil composition on adsorption of glyphosate and phosphate by contrasting Danish surface soils.

Authors: Gimsing, A. L.; Borggaard, O. K.; Bang, M.

Authors affiliation: Chemistry Department, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark.

Published in: European Journal of Soil Science, volumn 55, pages 183-191, (March 2004).

Abstract: "The herbicide glyphosate and inorganic phosphate are strongly adsorbed by inorganic soil components, especially aluminium and iron oxides, where they seem to compete for the same adsorption sites. Consequently, heavy phosphate application may exhaust soil's capacity to bind glyphosate, which may lead to pollution of drain- and groundwater. Adsorption of phosphate and glyphosate to five contrasting Danish surface soils was investigated by batch adsorption experiments. The different soils adsorbed different amounts of glyphosate and phosphate, and there was some competition between glyphosate and phosphate for adsorption sites, but the adsorption of glyphosate and phosphate seemed to be both competitive and additive. The competition was, however, less pronounced than found for goethite and gibbsite in an earlier study. The soil's pH seemed to be the only important factor in determining the amount of glyphosate and phosphate that could be adsorbed by the soils; consequently, glyphosate and phosphate adsorption by the soils was well predicted by pH, though predictions were somewhat improved by incorporation of oxalate-extractable iron. Other soil factors such as organic carbon, the clay content and the mineralogy of the clay fraction had no effect on glyphosate and phosphate adsorption. The effect of pH on the adsorption of glyphosate and phosphate in one of the soils was further investigated by batch experiments with pH adjusted to 6, 7 and 8. These experiments showed that pH strongly influenced the adsorption of glyphosate. A decrease in pH resulted in increasing glyphosate adsorption, while pH had only a small effect on phosphate adsorption."

Henry, I don't know if you have noticed but here at the FN forum, we speak from our hearts (experience) not from coping and pasting.

If your whole point is not to use RoundUp and if YOU don't want to use RoundUp, then don't, simple as that.

I have a funny feeling Henry is just searching the GW for Roundup and trying to pick a fight, thats all.

Sharon

I think he's not the only one who does that Sharon. It's called hippy bait.

Bravo Sharon! Couldn't have said it better myself. To each his own.......

Crazy_Gardener, I feel that we all can be better gardeners if we understand when to apply something and when not to. Your experience is probably very useful for people with your particular conditions, but I assume everyone in the far north does not have your particular conditions.

Jan said that she has a high pH. My last post gave the published research results for a high pH. If you have an acidic soil (low pH) this scientific paper is suggesting (to me) that your experience would not be applicable to her conditions.