If you want a "river," you need at least 150... I put 500 mixed color along the edge of my front landscape bed and got a "rivulet," nice effect! Over time, the blue ones out-competed the rest, so I'e learned to plant different varieties separately. ADR has a bulk tray of 2500 for $225...
M. latifolium bloom later and taller than the others, just so you know. trying to recall since I only have a scattered few.. but I think they are more likely to bloom with tulips than with daffs...
Muscari varieties Atlantic, Fantasy Creation. Valerie F, and Peppermint come in bulk trays half that size,,, you have me eyeing those now, thinking one of the kids who have learned to use my mini tiller could plow a curving line, then we could just toss in the bulbs...
