The soil selected for our rooftop containers is miserable. I’m guessing this is to limit weight as the “soil” looks to be about 25% crushed lava rock. Regardless it seems a safe bet that its not much good for growing. Rather than haul a ton of sand up to the roof we decided to pursue other approaches.
- Fertilizer & Bone Meal
- Cow & Sheep Manure
- Winter Cover Crop
Fertilizer & Bone Meal. Starting with fertilizer & bone meal, we’ve used it, but we’ve used very little of it. Generally just something added at the start of the year. The main reason we haven’t used it much is cost. No question it works… but it costs, and I’m cheap.
Compost. We’ve got a worm composter set up and churning through kitchen scraps on the roof. We try as much as possible to keep any remnants of meat or cheese out of the mix, and over-index on fruits, vegetables and egg shells. Further, over the winter while the worms are in slow motion I’ve been blending fruits, vegetable and egg shell scraps and digging them into the soil. Does it work? Who knows… but it doesn’t seem to hurt.
Cow & Sheep Manure. This one’s pretty simple. I buy several bags each year and dig it into the soil in our planters before planting seeds and starts.
Winter Cover Crops. These are a new approach starting last winter. I went with winter peas and rye grass… and it worked great. Let it grow over the winter, and in the spring cut it and dig it under. It seems to compost pretty quickly, and the legumes fix nitrogen for the season’s crop. My one learning from the first year is to start the seeds before winter arrives, so they have a chance to get to a decent size before the cold weather stalls them. This year I decided to repeat the winter peas and rye grass, but also added some crimson clover. Wish me luck.
Aaaand, that’s it. At least that’s it for our roof thus far.