Depends how many and how big they are, and how much time, fire will leave evidence, plenty to convict you unless its astoundingly hot (if they have a warrent and you have been served it, you will be charged with destroying evidence- at least IIRC in the UK)

garbage disposals can work, but hemp fibre will screw them up.

Best way, is Dont tell anyone , cover the smell and light, and dont deal, but most importantly Dont tell anyone

If you cant do the time, dont grow