Self-irrigating terrace garden

01 May 2011

We have the chance to live in an apartment with a big terrace. It would have been a shame not to take advantage of it and make it our own. Plus it's mostly oriented south, so we get plenty of sun in the summer.

Inspired by the many examples of sub-irrigated planters at insideurbangreen.org, and knowing that our graduate student lives would not leave us much time to water the garden on regular basis, we decided to use that system with reservoirs which supply water to the plants for weeks at a time.

Here's the actual concept, water is retained in reservoirs placed at the bottom of the planter, which have holes so that the soil can wick this water up. A tube is placed to allow these reservoirs to be filled from the top, and a drain makes sure that the water doesn't reach too high a level.

We scavenged free wood and wooden containers from various sources (lab crates at the university, free pallets and old bunk beds from Craigslist), which gave us plenty of material to work with and build planters. We made some with varying depths, to satisfy the needs of different plants, shallow for herbs, deep for tomatoes.

After building the planters, we lined the bottom with plastic tarp, placed the reservoirs wrapped with landscaping fabric, and added some coconut coir filler to act as wicking material. Finally we mixed some planting soil using compost, coconut coir and perlite, and filled the planters with it. We used home made soil because it would have been expensive to buy the 50 cubic feet that we needed of commercial potting mix.

In the meantime, our seedlings had grown indoors for several weeks and were ready to be transplanted outside, mostly tomatoes, eggplants and peppers. Outdoors, we also planted some peas, mint, and various herbs.