Heating soil to sterilize it is not an uncommon practice. But cooking weeds as stage 1 composting adds a whole new dimension to "compost wacko".

Karen

My question is about the time, I gave them 3 minutes in a food cycle bag, and there was no bad effects or smell problem, but I don't know that was enough to kill the seeds. They are very strong seeds.

Microwave weeds?

This sounds like something the Saturday Night Live Anal-retentive Chef would do.

{{gwi:313555}}

About the amount of time: I imagine the most important issue would be fire. If the weeds are at all dry when you put them in, they could ignite at some point I imagine.

To limit the problem myself, I just trash most weed seeds, then toss the rest of the plant into the compost. I do that with flowers that reseed like crazy, too. I cut most of the seeds off and trash them, then chop up the rest of the plant and compost it. It's not much trash at all but lots left for compost.

Karen

UH-OH, I added leaves and some nasty-looking tomatoes to my compost pile recently and have since learned that my plants had the blight that effected so many plants in the east this summer.
Does this mean that my compost is wrecked? It's not a huge pile and I've never been certain that it's heating up very well even tho' it seems to "compost".
Any advice would be welcome. Thanks.

Shouldn't you get some nerdy kid to locate the wattage on you microwave and take you utility bill and figure out how much it would cost to microwave weeds?

It's the soil that clings to the root of the weeds, that I don't want to lose. I have no problem losing the weeds. I have lots of other item to compost, but the soil from my garden is full of weed seeds, I get new weeds in one week,so I was keeping soil out of the compost bin, because I get less weeds coming up, but I hate to send all the good soil to the city compost. I worked to make it. It's a powerful microwave, a big one. I microwave old potatoes so they won't sprout in the compost, and it works.

To make this most effective you might try putting them in a plastic bag with a little water to steam them. They will heat up faster because water is a very effective microwave absorber, and the steam distributes heat very well throughout, so no hot and cool spots. If you're going to do it.

On the whole, considering the electricity input, this doesn't seem to be a very 'green' approach though. I might look for some other alternatives such as: weeding more aggressively, making a separate pile for weeds with seeds, or soaking in a drum or bucket of water (I've read about "weed tea" similar to compost tea).

That's my 4 cents, hope it helps.

OP said "I have lots of other item to compost, but the soil from my garden is full of weed seeds, "

As it turns out, every cubic inch of every soil is full of seeds. There's even a name for it -- The Soil Seed Bank.

Thus, every time you disturb the soil -- dig, rake, weed or simply scratch the surface -- you will provide appropriate conditions for at least some of those seeds to sprout and grow.

So microwaving the soil on weed roots won't get you any where.

Instead, plant your veggies in beds rather than rows. Space them so that the canopies will barely touch when they are full grown.

Before that occurs, add mulch to the soil's surface to limit the number of sprouting of unwanted seeds. Even with that, remain alert to the sneaky ones which sprout in spite of your efforts. Remove immediately, air dry, then put in compost.

I've got a yard full of "cleavers" -- Galium aparine. They have nasty NASTY sticky burs for seeds. Every one of them sprouts. The cats like to roll in them. My old compost pile is sprouting Cleavers faster than I can count. The new compost pile is full of pulled weeds, dead weedy turf, and all kind of compost that is filled with Cleavers.

I want to kill these things.

I've heard that cold composting will kill them.
I've heard that hot composting will kill them.
I've heard that high temperatures will kill them.
I've heard that nothing will kill them.

FWIW, a few years back I tried killing weeds in compost by baking it. STINK! Not worth the time and trouble and electricity for little pans full of stinky compost.

I tried microwaving them. Do you know how long it would take to microwave 2 yards of compost? Forget it!

If anybody knows know to kill off these Cleaver seeds, please do tell. Otherwise, I will buy another pair of gloves and just continue to pull weeds and weep for the next 10 years.

Rain2Fall

I baked soil to sterilize ONCE but never again - way too smelly.

I agree with jean001. We have seeds blowing in from the woods and pasture. The birds probably also bring them but sometimes there's a good plant they seed as well.

The best way to deal with weeds is to do an early thorough weeding as soon as one can tell the difference between a perennial seedling and a weed, and then just keep pulling them on a walk around the garden. Closely planted perennials, veggies, and tall lawn grass will prevent some weeds from sprouting. Mulching helps and cardboard under mulch even more so but those weeds will always be with us!

I heard baking was a bad idea due to the smell. The soil has moisture that I was using and I use a food cycle bag. I don't think the microwave using up much electric compared to other things like toasters. I can not find food cycle bags online anymore. They look like a paper bag, but are lined with cellulose. One could try a big bowl, but of course one can't microwave the whole garden worth of soil.

What are the weeds? Maybe you could eat them. I like thistles, nettles and dandelions.

Rain2Fall

I wouldn't recommend microwaving for a variety of reasons, primarily the odor produced as well as the unnecessary energy consumed with the bulk of product required to be 'cooked'. Hot composting IS an effective way to kill weed seeds but you must be able to generate sufficiently hot temps (130-145F will destroy virtually ALL weed seeds) and maintain them for at least 3-4 days.

The ideal way to control weed seeds in the garden is to A) mulch, B) manually remove ASAP any weeds that do grow and C) don't allow any weeds that survive A or B to go to seed.

And this tip from the FAQ of this forum may provide a more efficient solution than microwaving or if one is not able to compost fully. Note that the boiling water/steam will also destroy whatever beneficial organisms may exist, as would the microwaving.

Here is a link that might be useful: dealing with weed seeds

So many people believe hot composting will kill weeds, but it doesn't work for me. Maybe I can not get it hot enough, it's not that easy to get it hot enough, or maybe the weeds are very tough. Under perfect conditions you hear this all the time, it's like a myth. I often put desirable plants that have gone to seed into my compost bins to get seedlings of plants I like, but putting weed seeds in the compost is just going to make more weeds. It just makes a lot more work to compost weed seeds, but some people are into the fun of really getting in there and weeding constantly. I do use starbucks coffee and browns, it's just not powerful enough.

we used to microwave weed back in college......

wait a minute ......

sorry ----wrong forum !!!!!

I don't weed. I'm a mulcher.

SNORT!,LOL
Sorry I can't help, I got MG's and tom's popping up all summer long. YES my piles were hot! Not hot enough or not turned enough. Micro waved? No, I'm not that much of a "wacko" yet. BTW... how long are MG's viable????!!!!
:)Laura

"BTW... how long are MG's viable????!!!! "

I had an MG once that was about 15 or 20 years old. It probably should have lasted longer, but the prior owner didn't change the oil very often.

Somehow I get the impression that you mean a different kind of MG, but that's the only MG I know. What kind of MG do you mean?

Morning glories. They are so pretty but they don't play nice with their plant neighbors. I meant how long are their seed viable?
I know what a GM is but not a MG car. give me another hint.
:)Laura

MG Cars. They haven't been around for a while.

If you're talking about true morning glories, they're annuals and fairly easy to control.

If you're talking about field bindweed (sometimes called wild morning glory), you're talking about a perennial plant that spreads by root as well as seed and the seeds are viable for decades.

Mine are the annuals but they reseed like crazy!
are they viable for 10yrs too?
It's a loosing battle.
MG cars are cute. Reminds me of the great Gatsby, or the Godfather. not sure
:)Laura

Remember the old saying, "One year's seeding, seven year's weeding." Weeds are just a fact of gardening life. You can mulch like annpat or hand weed and mulch like me. Both work. I have very few weed seeds in the soil now after years of hoeing the young ones off regularly and pulling the ones that get past the hoe. The longer you mulch and compost the more friable your soil will get and the easier it will be to pull weeds. They all go on the compost heap except bindweed and couch grass roots. These are dried by hanging them over a handy object eg barrow handles, bushes etc. When they are desiccated they also go on the compost. (BTW my compost seldom ever warms up. It is slow and cold but it gets there in the end.) The idea of microwaving weeds seems frankly bonkers to me for a multitude of reasons. If you have so few weeds you can even contemplate microwaving them, hand pulling and composting would be much better for your soil and you (weeding is exercise) and for the planet (no electricity required). And I'm pretty sure that it would be quicker to hand weed given the capacity of the average microwave. If I were in your shoes I would simply knock off the soil clinging to the roots and just chuck them on the compost heap. I think you are in danger of over-thinking the weed issue.