You need to buy "heritage" seeds. They are pure strains, and NOT hybrids. Hybrid seeds only produce the desired "fruit" once, and then can revert back to an undesired parent.
There are tons of places to get them. Google "heritage seeds"
Kilz is one answer. You can use ANY odor blocking primer. Also, If they are hardwood, there is no problem, other than the sanding man. The odor is terrible!
The boards don't need to be replaced unless they are damaged. 2 coats of polyurethane will do the same thing as the odor blocking primer.,
If you have WD40 there, it works unbelievable well, BUT IT LEAVES A HAZARDOUSLY SLIPPERY COATING!!!!
Use it cautiously, with no one around, and wash the coating off IMMEDIATELY.
If you want to try before doing the entire floor, try it on a small spot to check.