|I'm now living in a house with a main house and a little studio in the back. The owner (my landlord and housemate) has the studio in the back (it's a separate building from the main house) and there will be three - eventually four - roommates in the main house. So far there are two of us, looking for a third.
The owner of the house has done some gardening, particularly in the backyard. He's got a fantastic collection of fruit trees, including some of those fancy types where four different varieties of fruit are grafted to the same tree, and several raised beds. He's also got a sophisticated greywater system going, and that all directs to the backyard. But the front yard, shown in the photo above, has nothing in it yet and it doesn't have any greywater hooked up to it.
Because we're on a slope, bare soil is prone to erosion. When it rains - you know, like once or twice a year here in San Diego, the water takes soil and nutrients down the hill with it. And very little of the water soaks into our front yard. The top few inches of the soil here are pretty silty/sandy, actually, which means some of the water can seep in (compared to the clay soil at my old place). If you're not familiar with the differences between clay and sandy soil, think about how fast the water drains from a hole you dig in the sand at the beach, compared to how well a clay pot holds water.
I started looking into the permaculture idea of swales and the owner of the house lent me a book he has called Gaia's Garden by Toby Hemenway. It's FANTASTIC. Based on that, I came up with a plan and implemented the first part of it.
A swale is a ditch dug into the soil with perennials planted on both sides of it. The soil removed from the swale is placed on the downhill side of it, creating a berm (a row of raised soil). When water flows downhill, it flows into the swale and stops. Then it soaks into the ground instead of traveling further down the hill.
Technically, a swale should have trees planted on either side of it, not smaller plants, because trees will have the ability to use all of the water that the swale collects, preventing the ground from getting waterlogged. But in San Diego, I can't imagine us getting ourselves waterlogged, given how little rain we have. Just in case, I decided to do relatively small swales that are spaced closer together than swales should be, so that each one won't accumulate so much water. And there will be a tree or two in the front yard to soak up some water... what little we have.
Step one is finding the contours of the yard. You need to make your swales on a flat surface so that the water doesn't just flow to the lowest corner of the swale and overflow right down the hill when it gets full. To find the contours, you need a tool called an A-frame. I made a VERY rustic one with a sawhorse, some yarn, masking tape, and a pair of scissors.
An A-frame must have equal sized legs and a bar in the middle forming the shape of an A. From the top, hang a string down the middle and weight it down with something heavy (I used scissors). To use your A-frame, first place it on ground you know is level. I used the floor of our house. Mark where the string falls on the horizontal bar of the A when it is on level ground. Any time your A-frame stands on level ground, the string will find that mark. When the string falls somewhere else on the horizontal bar, then you are not on level ground.
I thought I could just eyeball the contours of the yard, but once I began using the A-frame, I realized that I could NOT just eyeball it. I'm glad I went to the trouble of doing this correctly (especially now that the job's mostly done because it was SO MUCH WORK).
Find flat ground with your A-frame and mark off where both legs stand. Then move it over to one side so that you can continue marking off your contour line. I'm sure there's a better way to do this than what I did - something more permanent and clear - but I just used a pitchfork to make a mark in the ground along the line.
My contour line
Then I marked off two more contour lines in the front yard. At that point, it looked like the yard had been attacked by an army of gophers!
All three lines, although the last one isn't very visible.
The back two lines
Then I set to work removing dirt from the first contour line. You never know what a big job digging will be until you start, and in this case, it was a real mess. The sandy/silty layer of the soil was held together by small but plentiful roots from the grass and a plastic net put in by whoever put in the lawn. Below that, the yard was chock full of enormous woody roots from a nearby tree or bush. Several inches below the top layer, there was a layer of reddish subsoil that seemed to have a bit more clay in it. It wasn't too difficult to get through - or wouldn't have been without those woody roots.
I decided somewhat arbitrarily (albeit based on a neat Filipino system of farming on sloped land I read about) to make the swale 50 cm wide. At first I stopped when I hit the subsoil. Eventually, I went deeper with the goal of digging it a foot deep. It's probably more like 8" deep. Here's where I stopped after the first day:
After a shower and a hot meal, I made a plan. First, I looked up plants that can tolerate both wet and dry conditions. Cacti and succulents are drought tolerant but water will kill them. For a swale that isn't going to get much in the way of irrigation, we need plants that can take the water when it comes and live without it during the summer. Fortunately, Gaia's Garden provided a list of plants that fit the bill. I wrote up the following list based on the book:
- Aloe vera
- Grape (not for here though bc it's a vine)
- Lemonadeberry (a Southern CA native)
- Sage (we have lots of native sages)
- Summer Savory
To that list, I added marjoram, which is very similar to oregano, and three nitrogen fixers that can deal with both wet and dry conditions: Bladder Senna, Lupine, and Russian Olive. Of the three, I had only heard of Lupine.
Then it was off to City Farmers Nursery to get the plants and a few other things. The entire shopping trip was an expensive one, but it can be done for cheaper if that's an issue for you. Many of these plants are hard to grow from seed but easy to grow from cuttings. So if you need to work on the cheap, just get one plant of each species you want or need, make cuttings, and grow yourself some more plants.
I asked the home's owner what he preferred - cloning one variety of, say, oregano, or buying several varieties of the same species - and he replied "Variety is the spice of life!" So I had fun finding different varieties to plant. In the end, I brought home 11 small plant starts, one packet of lupine seeds, a bag of worms, and a bale of straw. Here's the plan I came up with for my first swale:
My plan on paper.
My plan laid out in the yard.
As you can see, I dug the ditch, then planted perennials on either side of it, spaced about 2 feet from one another. They will eventually grow to fill up the whole space. I got two types of lavender, two thymes, two oreganos, rosemary, aloe vera, yarrow, and catnip.
Continuing with advice from Gaia's Garden, I wanted to line the whole area with a thick layer of mulch. That's what the straw is for. But wheat straw - which is what I bought - has a Carbon to Nitrogen (C:N) ratio of 80:1, and that is too much carbon. I also planned to use my cardboard moving boxes now that I'm done moving, and cardboard has a high C:N ratio too.
Soil microorganisms tend to consume about 20 to 50 parts C for each part N they gobble up and when you feed them with too much of one element, you end up with a shortage of the other. I needed more nitrogen. We don't have any finished compost here yet, but we do live near the beach. I brought an empty bucket with me, stopped at the beach, and filled it full of seaweed. Seaweed has a C:N ratio of 19:1. After I got home, I rinsed it in freshwater a few times before using it.
(If you're trying to replicate what I've done, you don't need to use the same materials I used. Just use any organic matter you've got, as long as it's free of toxic pollutants. I went with seaweed because I live right near the beach. When I lived further from the beach but had a compost pile, a worm bin, and a chicken coop with ready to use goodies, I would have used compost, worm castings, and composted chicken litter. Not to mention yard waste, like the branches and dead leaves pruned from trees.)
Then I got back to work!
I put down a strip of cardboard on the downhill side of the swale and cut an X in it below where the plants would sit so that its roots could dig deep into the soil even before the cardboard breaks down. Then I put some seaweed on there and shoveled the soil from the swale on top of that. When that was done, I planted the starts.
You can see all of the layers here - cardboard, then seaweed, then soil, and a plant start.
With the soil out of the swale, I lined that with cardboard, then a layer of seaweed, straw, seaweed, worms, and more straw. Then I watered the whole thing. Straw breaks down really well when it's wet, and the worms like an 80% moisture content. I used only half of the worms in the swale and used the rest in the compost bin, where they will multiply rapidly. Next time we make a swale, we can just grab some from the compost instead of buying more.
As I think about it now, I wish I didn't use the cardboard because it isn't good at allowing water to pass through it before it fully breaks down. Fortunately, the cardboard boxes I used had holes in them for the box handles, so the water will be able to get through the cardboard through those holes.
On the uphill side of the swale, I simply planted the starts and mulched them in with straw. If you try something like this in your yard or garden, use way more mulch than you think you need. I found out the hard way this summer that using a ridiculous amount of mulch (6 inches) works really, really well and if you don't put all of that mulch down when your plants are small, it is MUCH harder to do it once the plants get big.
By dinner time, I was mostly done. I still have 2 more plant starts to go, and room for a few more after that. Either I can clone something, buy another plant, or plant the lupine seeds and wait for those. I've also got enough straw left to finish the job, but I could definitely use more if I had it. Here's how it all looks right now:
From above it on the hill
From below it on the hill
Envision the entire space covered in lush, healthy plants. The starts will get big to cover it all - which is what I assured the neighbors who stopped to see what I was up to. In the short term, I might plant fava beans in between the perennials to fix some nitrogen in there.
Now that the first swale is almost entirely done, I think I might just put two swales in the front yard - the one I already made and a second one that is in between the back two contour lines I made. They are expensive, they are a ton of work, and they are five feet wide when all is said and done - especially if you consider that you'll want a path for walking on either side of the perennials so you can prune, weed, and harvest them. With 18" paths, that adds 3 more feet.
In the middle of the two swales, I'd like to eventually have a garden bed to grow annual veggies. That will need to be about 4 feet wide. Therefore, I should have located my two contour lines 12 feet from one another. Instead, I put them nine feet apart.
- Plants: $3.19 each for 10 + $4 for the aloe
- Seeds: $2.19
- Straw: $13.95
- Worms: $14.89
- Total: $66.93