Hi Rohima if you are sure there are no weed seeds in your own compost go ahead and use. We tend to put on the veg. garden as it doesn't matter then if there are weeds.

I mix home made in to my bought compost all the time but it is not heavy. I do keep a look out for weeds though as the heat required to kill off weed seeds is not normally generated in small home composters. If your geraniums are going in pots this will not be a problem and you should be able to see noxious weed roots like couch grass or bishop weed when you are doing your mixing. I have a lot of bins and can leave them rotting for anything up to 4 years. I also use garden soil to mix with the new compost so as not to upset the balance too much.