Weather Extremes Perplex the Plants

Hail storms in cactus country!

May 15th, Puebla - A lot of gardening is simply trial and error to find out what works best under the particular conditions on your patch. The effects of the rooftop's exposure to the elements continues to surprise me. A recent hailstorm came in sideways and ripped up the seedling bed. Birds also picked out some of the seeds before they had a chance to germinate. The hail also left cold burn marks on the leaves of some plants and tore others completely apart.

Hail and bird damage to seedlings

The hot, dry winds create a high evapotranspiration rate, so the seedlings have to be watered at least 2 or 3 times daily. For the same reason, I cover all soil with a few inches of wood chip or straw mulch. Mulch should be applied thicker to plants that bear fruit near the soil, such as strawberries, to keep the fruits clean and dry.

With a house full of people and frequent events to promote local food sustainability, local artesanal products, arts, music and spirituality, Casa Sattva generates a lot of kitchen scraps. Since our capacity to compost is limited it is smarter for us to be more selective of our materials, how they are handled and where they end up. We have a three-stage composting system. First, the “green” food scraps from the kitchen are collected in a bucket. Ideally, everything is cut into small pieces and the harder materials (avocado and mango seeds) are taken out. The second stage is a bigger container on the roof, where kitchen scraps will collect and start to break down before being added to the main compost bin. It's helpful to let the microbial action begin to decompose the material before feeding it to worms, so that they can get to work on it right away. It also won't slow down the decomposition rate of the main bin (where temperatures are much higher), which would happen if you added greens fresh from the kitchen.

I've been turning the compost in the main bin about twice a week. About two inches deep the pile is steaming and the dried leaves are breaking down reasonably well. At first, the pile was way too heavy on green materials (too much Nitrogen) and produced a foul smell of fermentation. My only real Carbon source has been Eucalyptus leaves from a local park. The breakdown of these leaves produces a natural herbicide and may prevent seeds from germinating, but since we've germinated everything in trays it won't be a problem to add the compost when we transplant. I pick out the small stones, twigs and leaf stems and then crush the leaves by hand. A grinder with a hand crank would be amazing and we're looking for something that could handle leaves as well as the kitchen scraps. I mixed in crushed leaves and small handfuls of dried bokashi (fermented compost) to soak up the excess water and balance out the Nitrogen-Carbon ratio. I'm also using four small PVC pipes for aeration by drilling them full of holes and sticking them into the pile.

Proper aeration will greatly speed up the composting process

These changes seem to be working: the compost smells earthy throughout and it's breaking down relatively fast. When I turn the pile, the bottom six inches are usually quite wet and smell a bit off, so I've started mixing in fine wood chips and dry bokashi. I've stopped added wood chips to the worm bins. What I've added already is slowly breaking down, but the worms aren't eating them.

Sub-Irrigated Planter System Update

Observe your "ground" and plan the arrangement
of the different components

Water barrel along wall to catch rainwater.
Two rows of bins running North to South.

After a lot of trial and error the sub-irrigation system is finally ready to be planted! We sanded down the wooden pallet platforms and gave them a coat of Thompson's Water Seal to extend their life a bit. The sun had already warped some of the planks, so I straightened them out again with extra nails. For this system to work, it's crucial for the bins to be at exactly the same level, which can be a bit tedious with uneven platforms on top of an uneven roof, but luckily the solutions are simple. 

All surface structure must be as level as possible

Use a bunyip water level to check between points

The difference in water levels between poles will tell you
how high one spot is relative to another. Adjust accordingly.

Use thin pieces of wood to prop up low areas

I used a bubble level and a bunyip water level to check all points of the two platforms against each other and then slipped thin pieces of wood (the sides of wooden fruit boxes) underneath the platforms and the bins as necessary. If you have a shallow water control bin, it will help to position it so that it's base is a few centimetres above the base of the growing containers. This will allow you more room when adjusting the water levels. The float pump that I used for the control bin only allows set adjustments, which happened to be too significant to get an accurate water level, so I just removed it and bent the rod a little bit with a hammer. 

Rain collection barrel, to control bin,
to two rows of growing bins

Testing water flow to first bins

Once you have the desired water level achieved in all bins, use a marker to draw a spot 10mm or so above the water and then make a hole with a drill or a knife. To stop the leaks in the tubes or connecting pieces I took apart the joint and put teflon tape on the threading. The system is now leak-free without using silicone or other sealant.

Double and triple check. Things will shift a little bit.

Make a drainage hole once you've achieved desire water level

Again, check the resources from Montreal (www.alternatives.ca / www.rooftopgardens.ca) for a more detailed trouble-shooting guide for a sub-irrigated system, but knowing that water will always be level with itself you'll easily be able to figure out which areas are too high (lower water level) or too low (higher water level) and making the necessary changes will just depend on the components of your system and the “ground” you're working on. 

Fill wicking baskets with peat and perlite.
Add compost and other soil amendments
to the rest of the mix.

To protect the plastic bins from sun damage and help keep the soil cool I cut up recycled vinyl posters and wrapped them around all three bins. At the top I had them reach over the sides of the bin and by making a few cuts was able to fold a section into the bin and then attach them near the rim with two holes an inch apart and a zip tie. 

Recycled vinyl posters for protection from sun

Once we have shade cloth installed the new beds will be ready for the seedlings. Trials of putting recently transplanted kale and bok choy into a few hours of late afternoon sun showed that the young plants just can't take the exposure. Even two established dwarf tomato plants are showing signs of stress. Some of the leaves were drying up when I bought them and it hasn't been able to recover, although tomatoes seem to be prone to so many pests and diseases that it might be a mineral deficiency. And then we could chase our tales pinpointing the absolute root, if such a thing exists: is it the soil, the air, the water, and which one of the dozens of minerals or trace elements are missing or too abundant in the equation? Maybe let's not think about math, and just look into it, ask someone, read something and when it's time to act, just do what feels best with what you have and wish for its brightest growth. If some blind people can reach deeper into other levels of sensorial awareness, to which depths plunge the fibres of plant consciousness? They seem the quintessential givers, forever budding and opening itself unto the world. Read some of the "Secret Life of Plants" and maybe take another look…cause for many, I'd guess that it's too easy to forget. Thank you little veggies and fruits. The more I appreciate you, the less my need for cruder foods, and food in general, as the burst of a bite of cucumber seems to fill my stomach 1/50 full and there's so much flavour! Eat on.

The rooftop garden here at Casa Sattva will be hosting a series of workshops on Urban Permaculture this week, so stayed tuned for the next posting which will feature some of topics we discuss. We might even have a roof by then. Fingers crossed!

To read more about Casa Sattva and the event click on this link.