Saturday, June 15, 2013

Building an Herb Spiral

Several months ago I was playing with the idea of building raised beds to grow vegetables - or at least the ones I use to make salsa. As I was looking for information about raised beds, I stumbled across a reference to a permaculture structure called an herb spiral. (Am I the only one who had never heard of permaculture?)

All planted!
Intrigued, I looked for more information. Everything I found was fascinating. Because of its unique shape, the spiral creates different microclimates in different sections of the bed. That makes it a perfect place to put all of those kitchen herbs - even the ones that usually can't be planted together because of sun or water needs.

I decided I had to have one. A quick search showed several videos on how to build them. Easy peasy, right? I just needed to collect the materials. I decided that I'd rather use reclaimed brick or stone to build my spiral, rather than buying new material. I ended up getting my bricks for free, but lots of people sell them for 10 or 15 cents a brick if you come pick them up. The price was definitely right, and it's greener to reuse than buy new. Win, win!

I was never able to find an exact list of what you need with amounts, so here's what I used. Obviously these numbers are going to vary with the size and shape of your spiral, but you can use this for a frame of reference.

200-250 bricks (plus broken pieces as needed for edges or weird spots in the spiral)
480 lbs. manure (I used 12 bags, 40 lb. each)
1 bale straw
Compost - I don't have exact measures here because most came from my compost heap. I used two standard wheelbarrows full of compost, plus 3 bags (.75 cu. ft)
Herbs for planting - So far I have Rosemary, Oregano, Thyme, Basil, and Sage
Cardboard - I ended up using two pizza boxes and three mailing boxes, but I could have used more.

First round, before adding more cardboard
I started out by laying down cardboard where I wanted the spiral to be. I needed it to be sunny, and close enough to the kitchen that I will actually go outside to get the herbs when I want them. The spot I chose ultimately wasn't as level as it should have been, so look for level ground as well. The cardboard should cover where the spiral will be and extend a few feet from the spiral. At first, it will kill the grass and weeds underneath, then it will provide a layer of mulch.

I saw lots of different ways of marking out the spiral, but I am not much of a planner, so I just laid it out freeform. It worked out pretty well, though I did have a partial collapse on the east side as I was filling in with manure and compost. This is why we choose a level site. Lesson learned.

Notice the lean out on the left side.
The spiral should spiral around and up so the part in the center is about a meter tall. The goal is to make everything easily reachable from the edges of the spiral. When I stand at the edge, no matter which side I am on, I can reach everything from there to the center.

The videos and websites I found all said to wet everything down between layers, but I had a couple weeks while I was looking for more bricks, and then a couple more while I was getting compost and manure. I figured the rain did a good enough job.

Next in is the straw. I put a good thick layer all the way around the spiral. After that, alternating layers of manure and compost, making sure to have compost on the top to plant into. I wasn't terribly careful with the thickness of the layers, I just layered it in there. Each layer should be wetted down.

Ready to plant!
Once everything is full, you can plant directly into the compost. Herbs that like sunny spots and well-drained soil go towards the top. I put rosemary at the very top because I like the look of it there. As you move down the spiral, the water will drain downhill, so the soil will get progressively wetter. Higher parts of the spiral will cast shade onto lower parts throughout the day, so plant accordingly.

I bought some herbs, thinking I would have the bed mostly full, but I barely made it halfway around the spiral. It's like a TARDIS herb garden - definitely bigger on the inside!

All finished. Maybe we need some mulch on the top layer...