There's a number of Sosnowsky's hogweed (Heracleum sosnowskyi) plants which have blossomed a while ago and now they are standing with dry seeds ready to be spread by wind. Suppose I gather the seeds (that isn't dangerous when the plant is already dry). There will be perhaps a liter or so of them.
I want the seeds deactivated such that if they fall into soil they definitely give no seedlings ever. Having them destroyed by burning (or throwing into molten steel) would do but that isn't necessary, all I want is to be sure that all the seeds I get through this deactivation procedure give no seedling if they ever fall into soil. So for example burning doesn't look good because how do I ensure that all the volume has burnt fully or at least heated to high enough temperature?
Deactivation procedures should preferably not require complex handling of seeds afterwards. So for example some dangerous chemical wouldn't be optimal because how will I then dispose the contaminated seeds?
Should I boil them? How long would be enough?
Should I soak them in boiled water? Is that enough?
Perhaps some rather safe chemicals would do?
What's an easy, safe and reliable way to have seeds deactivated?