Making compost

Hi, Undergardener, good question, I would like to know the answer to this one too.

Happy Gardening, Marge.

if you build a heap all at once from a mixture of plant material grass cuttings kitchen waste and such and water it well, the heap (if in some sunshine) should build up enough heat to kill off any weed seed and flower seed, (hot heap) but if like most folk you build a heap gradually over the year (cold heap)you may get some seed growth from it ,which is why I don't like putting tomatoes and potato skins on the heap

Hi undergardener, The answer is ....you could do. but I have to tell you my experience, We dig all our compost including spent pots and baskets into the veggie patch, and this year , as the veggies were growing, so were some seeds,as the veggies were being used, I let the seeds grow on and by september i had petunias, lobelia, and nastursiums all taking over, but I wasnt bothered as it looked lovely and the frost will kill off what remains before the the new year manuring and composting again. I personally dont mind a few flowers in the veg patch as long as they over rule you can always pull them out once they are big enough if it offends Happy Composting

I have read that in order to generate enough heat to kill off organic matter in compost heap the volume has to exceed 1 cubic meter.
i.e. 1mX1mX1m.
So you would need a large, full, well insulated cubic or spherical heap.
The same applies to diseased matter, which should be kept away from the heap unless it can generate a killer heat.
I have sucessfully germinated over winter an acacado in my composter (accidental)