Hi Linda,
I would be very careful about using Johnson Grass. The stuff is terribly invasive by me. It’s seeds sprout no matter how wet or dry the conditions and once it gets so much as a toehold, it will spread by both seed and rhizome. I tried all sorts of ways to get rid of mine when it first appeared about 15 years ago, but nothing stopped it. Best I can tell, the best way to treat for Johnson Grass is to not let it near in the first place. If it does get in, I suggest keeping the affected area plenty fertile so other grasses will naturally compete. Frequent mowings seems to at least slow the stuff down a bit, maybe stunting or even killing it in conjunction with other ground covers that may favorably compete.
I can totally believe that someone would want to
sell you Johnson Grass hay/straw. The stuff is a C4 plant so it is a very efficient user of
water and sunlight. It grows 6 feet tall or taller in the right conditions and can really take over open pasture. Early on there was some concerns about Johnson Grass having a high silica content that would be poisonous to herbivores. My understanding is that the silica did not toxify the animal, but made the grass difficult to digest. I believe these fears have been demonstrated to be unfounded. I don’t think that Johnson Grass is so much toxic as it is a nuisance. But if you get Johnson Grass in your garden, I believe you will regret ever purchasing it in the first place.
These are all my experiences and I wish you the best.
Eric
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