As written in earlier posts the “soil” in our rooftop garden is miserable, made up of sand, lava rock and who-knows-what else presumably to keep it light given the volume up there. I’ve had reasonable success growing in this medium with limited use of compost / worm castings and fertilizer, but my compost bin is limited and the soil volume is substantial.
This year I’m considering fabric grow pots / bags (Amazon Canada has Vivosun grow bags here) for some of the more demanding produce so I can supplement the soil more deliberately through the season, and recover that soil at year’s end rather than have to remember where supplementation occurred for the next year.
From what I’ve read, the 5 gallon fabric grow bags should do for my needs, in particular for use with some of my super hot peppers. I’ll continue to grow most of them in the main planters, but intend to use 3 or for grow bags for comparison this season. I’m assuming the 5 gallon size would suffice for tomatoes as well, and so I’ll likely consider a comparison there as well.
If anyone has any experience using these I’d love to hear about it. I’m particularly curious how well they stand up to weather… can you really expect to get 5 to 7 seasons out of a single bag?
This past summer I tried tested black landscape fabric as a weed barrier, and heat retention tool for my pepper plants. The idea being that a) any weeds that germinated in that planter would be starved for light unless they could find a path to one of the holes where the peppers were planted, and b) the black colour of the fabric would serve to capture the sun’s heat, bringing the soil up to a temperature preferred by peppers even on cooler days.
What did I learn?
Weed suppression. Well, a single layer of landscape fabric doesn’t seem to starve weeds of light or water. Weeds still germinated and grew under the fabric. In some cases they surfaced through one of the pepper holes, but in many cases they didn’t, yet still appeared to grow well. Despite this, they were restricted to the height they were able to push the fabric, and so didn’t compete with the peppers vertically for sun. Not what I’d expected, but less work than the constant weeding needed with bare soil.
Heat capture. Landscape fabric does seem to trap the sun’s heat in the soil. Comparing the temperature of the soil under the fabric to the surface soil of a neighbouring bed showed clearly that this worked.
Surprise! There was another learning from this ‘experiment.’ When the pepper plants were the only plants accessible in this particular bed, they were the only plants that avian pests targeted. Crows are smart, and they watch every year as I prepare the soil and plant seedlings. It seems that the black tarp may have brought an appealing focus to the seedlings planted, and almost half of them were uprooted by curious crows over the course of several weeks. Eventually they seem to realize that pepper seedlings represented nothing of interest , but in the meantime halved the number of plants for the 2019 crop.
So, would I do it again? No. At least not the same way. I think next year I may encircle my seedlings with some of the fabric in service of heat capture, but I’m not going to blanket the entire bed. Additionally, I may consider covering the bed with netting or something similar until the plants are off to a good start to prevent the crow disaster from this past year.
As I mentioned previously the soil in the planters that we use is less than ideal. We’ve taken to amending it with purchased compost and manure each spring, which has had a noticeable effect on production. While purchasing soil amendments is fine, we’ve also set up a worm composter on the roof to provide additional, free nutrients to the soil.
First, we don’t have the smaller, apartment worm composter that is provided by the city following their composting courses. We’re currently using the Worm Factory 360 Composting Worm Bin which we were lucky to pick up on Craigslist. This bin has 4 separate trays that stack one inside the other which lets you build your compost in stages, and makes separating the worms out easier. Additionally, there is a final, lower tray used to catch the compost tea, and a spigot to let you drain it when desired. Using the Worm Factory 360 has come with learnings that I will share here.
Keep the compost bin in a somewhat sheltered location. The trays aren’t sealed, and water hitting from the side will get into the trays. We live in Vancouver, and it rains A LOT. To prevent the trays getting too wet, we’ve positioned out bin where it is open from above to allow some moisture to hit the composter, but where it is protected from the sides.
Keep the composter’s spigot open. I know, this robs us of the compost tea, but we’re not diligent enough to keep it drained enough to avoid the lower tray from getting soaked. If you’re checking on the bin daily, then maybe closing the spigot is fine, but otherwise consider keeping it open. It also helps that our bin is on a grassed area, so the tea doesn’t cause any mess.
Do not compost large pieces of bread, and any meats/cheeses. We don’t have rodent pests on the roof, so the typical rodent risk related to meat/cheese isn’t an issue. That said, we do like to avoid smells, and further we’ve found that any dense break/cake etc tends to not break down and instead just mold.
Rotate the compost trays. We keep the trays with the freshest material in the bottom, and the oldest/most ‘ready’ tray at the top. I’ve found that the worms in that top tray, once they’ve finished the available organic matter start to migrate down to lower, more nutritious trays, making worm extraction much easier.
So far we’ve made due with a single Worm Factory 360 Composting Worm Bin but given interest from others in the building, we’ll be looking at purchasing additional, or some other, larger bin to accommodate the available vegetable waste. At this point I’m thinking about either a tumbler / rolling composter, or one of the more pleasantly designed aerobins like the ones on offer at Amazon.