Forest Garden

A Forest Garden is a very unique thing. A lot will depend on the space you have available, the lay of the land, and your climate, to mention just a few variables. Perhaps the best thing to do at this point is to give you an idea of our specifics, so you can decide which pieces of information will be relevant to you, and which you will need to adapt.

Our eventual goal is to terraform our whole 10 acre property, but we’re starting with a 3000 square foot area south 0f the house. This first orchard consists of four terraces, each more or less 10 ft. by 80 ft. It’s part of a south facing hill made up of clay and rocks. Native plants include oak, juniper, and acacia, and there are many edible weeds (like lambs quarters, amaranth, and purslane) that grow wild. In an average year, we get about 25″ of rain a year mostly from June through September, with annual temperatures between 25 and 105 degrees F.

It might also help to mention some of the things that helped us decide where to put our first Forest Garden. First, we wanted to be able to see it from our large, south facing windows, but didn’t want to risk a tree ever falling on the house, so it is further from the house than the tallest type of tree that we’ll be growing. Secondly, rain water catchment is the sole source of water for our property, so we didn’t want to clog up our gutters with a bunch of leaves and such. We therefore didn’t want the house to be directly downwind of the trees. Thirdly, we wanted it to be downhill from our irrigation tank, so that watering wouldn’t require any pumps. Fourthly, we have trenches that flow through the orchard that collect runoff from the road and house area, and those trenches then overflow downhill into the big pond, in case it ever rains too much.

You also need to consider pathways during the planning stage. We have a wide path at the top of each terrace, which also serves as a swale and infiltration trench from heavy rains. There are then several paths, or steps, that connect one terrace to the next.

Once you’ve decided on the size and location of your orchard, you will have to mark it on the ground.

1. You want your terrace to slope down gradually, so that water will run, but not too fast. We have a drop of about 1-2 inches for every 10 ft. of horizontal terrace. Now, to mark this, we’ll be using a water level and we’re going to put a rebar in every 10 ft, as that’s the distance between our trees (for the most part). So, you want your clear hose to be about 20 ft. long, to cover the 10 ft. we’ll be measuring, as well as enough to come up to eye level on each end.
2. Place a mark all the way around one pole at 46″ from the bottom. This will be the pole used by the person standing uphill.
3. Place a mark all the way around the second pole at 48″ from the bottom. This will be the downhill person’s pole.
4. Fill the hose with water, leaving a foot or so empty on each end. Make sure there are no pockets of air in the hose. If there are, lift one end of the hose to move the bubble, and keep moving it until it reaches one end. When you need to put the hose down, bring the two ends together and place them higher than the rest of the hose. Alternatively, both people can hold their thumbs over the ends.
5. Put a post or rebar in the highest corner of your most uphill terrace. This will be where your water supply will come from, as everything else should be downhill from here. The uphill person should stand with his/her pole at the base of this post.
6. The second person moves roughly 10 ft. away along the length of the first terrace. You can use a 10 ft. long string or tape measure between the two people to quickly measure this distance, and it doesn’t have to be exact. The downhill person should put his/her pole on the ground.
7. With the clear hose stretched between the two people and up the length of each pole, raise or lower the hose until the uphill person sees the water line match the mark on their pole.
8. The downhill person needs to move their pole up or down the hill until the water line is also on his/her mark (which is two inches off level). Put a post or rebar in at this point.
9. Now, the uphill person moves to the rebar, and the downhill person goes 10 ft away and repeats the leveling process.
10. Repeat this process until you reach the end of your terrace.
11. Put in a couple of posts or rebars in a line parallel to this first line you made. In our case, our terraces are 10 ft. wide, so we made the second line of posts 12 ft. away from the first, which allowed for the terrace wall.
12. You can mark out each terrace if you wish, or just start with one and carry on when your first is finished.

Soil with a high organic content stores water considerably better than bare soil, which has some definite advantages. For a start, it’s a cheaper form of water storage than making ponds or tanks. Plus, it’s right there where your trees can access it as needed, decreasing the amount of time that you will have to irrigate them.

The first layer of organic content that we’ll be adding consists of things like branches and logs. As the wood rots slowly under the ground, it will hold water, add air pockets and provide a home to all kinds of mycelium and micro-organisms. The idea is to create an organic sponge that can store both nutrients and water.

1. To level each terrace, we used a mixture of digging out (which we got our pigs to do) and filling in (which we got our chickens to do), but before you begin either, you will need to build a retaining wall on the inside of the downhill line of posts. It needn’t be very tall and you can use whatever you have available. We used rocks, as our property is full of them. Rocks also hold heat very well, so we can plant any plants that need a little extra warmth and protection in winter at their base.
2. Once you have a row of rocks all the way along the terrace, put a bunch of sticks, logs and twigs up against the inside of the retaining wall.
3. Add a thick layer of manure, compost and/or weeds on top of the branches.
4. Dig a ditch, about 18″ wide and at least six inches deep all the way along the top of the terrace. This will act as a pathway and swale. Throw all the dirt form the trench on top of the wood pile.
5. At each tree spot, dig a wide, deep hole. Remember that our natural soil is clay, so we like to dig a hole and then add some sand, compost and loamy material with the clay. This gives the trees a better start. To this end, we keep the topsoil to mix back in to the hole, but the rest we throw on top of the branches, mixed with a bit of manure and/or compost.
6. Whenever the soil you are filling in on the downhill part is about to get higher than the rocks, add another layer of rocks. However, move the new layer in a ways, so that they’re sitting largely on the new soil (compact it a little first). The retaining wall will stair-step as it rises. This will increase the stability of the retaining wall.
7. Continue adding material until the “downhill” part is higher than the ground at the base of the tree spots.

We built a 7000 gallon tank specifically for irrigating the orchards, which is filled during rain season from the house roof. We dug a trench from this tank to the orchard. In this ditch we laid a 3″ pipe that connects to the tank’s overflow (so that when it’s full, its excess will feed the orchard), as well as a 2″ pipe from the irrigation tank to the main irrigation lines.

We use a two tier irrigation system. One line waters the trees and shrubs underground, so that the water goes straight to the roots without losing moisture to evaporation. The second line is a drip system that waters the plants that surround each tree or shrub spot.

Keep in mind that plumbing is a lot easier to do than explain, so even if you have no experience, don’t be put off. Looking at the photos will definitely make the descriptions easier to follow.

1. The first pipe we’re going to deal with is the 2″ PVC pipe that runs north to south, from the tank, across the first 10 ft. wide terrace and on to the other terraces. All PVC parts should be cleaned with PVC cleaner and then glued together, pushing and twisting the pipes together while the glue is fresh. Make sure that all Ts and such end up facing the direction you want them to.
2. Within this pipe there are three 2″ Ts. The first two Ts connect to the irrigation lines via a 2″ to 3/4″ bushing (adaptor). The 3/4″ part is threaded on the inside (female).
3. The third T is a little different. Its horizontal parts are 2″, but the vertical part is 3/4″. Ideally, this is want you want for all three Ts, but it is much harder to find than the regular Ts and bushings. This third T connects to a garden hose for spot watering and planting.
4. The 2″ PVC pipe ends with a coupling that is threaded on the outside (male) of one end. We then have a cap that screws on to this coupling. This allows us to add on to the 2″ line when the next terraces are ready.
5. So that’s the 2″ line done, now let’s go back to the garden hose T. Screw in a 3/4″ nipple to the 3/4″ threads in the T, and then screw a 3/4″ valve to the nipple. Then screw in a pipe to garden hose adaptor, and attach your hose. This is a little more expensive than using a regular garden hose valve, but it lasts longer and allows more water flow.
6. The other two Ts each have a 3/4″ nipple screwed in to the 2″ to 3/4″ reducer bushing. Then screw in a 3/4″ threaded valve on the other end of each nipple. On the other side of the valves, screw in a thread to hose adaptor. Put a length of 3/4″ irrigation hose that runs the whole length of the terrace onto each of these adaptors. Make sure you have a hose clamp on the pipe before you push it onto the adaptor (if it’s hard to push on, heat the end of the hose by moving a flame all around it or by sticking the end of the hose in very hot water). Tighten the hose clamps.
7. One of the 3/4″ hoses will be deep watering trees and shrubs. At each tree or shrub spot, put a 3/4″ pipe into the hole when you dig it out to plant. Drill holes all the way along its length. The pipe should stick up above the ground a few inches. You can then put your tree in the hole and fill the hole with soil. Then, make a hole in the 3/4″ irrigation hose (a nail should do the trick). Push in a 1/8″ emitter valve into the hole. Attach a 1/8″ hose to the valve and put the other end of this hose into the 3/4″ pipe that’s sticking out of the ground. You can turn this valve on and off, as well as adjust its flow by having it somewhere in between.
8. The other 3/4″ irrigation hose is for everything that will be planted around the trees and shrubs. With a nail, make a hole at each tree spot and put in a 1/8″ emitter valve. To the other end of the valve, add a 1/8″ T. Make a loop of 1/8″ hose that goes all the way around the tree in a circle. It should be right on the edge of the tree hole. Connect each end to the T. Wherever you want to put a plant, cut the hose and put an in-line drip emitter. We usually put 3-5 drips around each tree.
9. Cover the main irrigation lines with dirt, and the emitters and 1/8″ lines with mulch. You should also paint the PVC that will be exposed, as the sun can damage PVC.
10. During the dry (and hot) season, we water our forest garden three times a week It is better to water occasionally and deep rather than shallow, but frequent waterings. Learn to use your plants as an indicator of water needs.

So, you’ve got the terrace, soil and water system ready, now what do you plant and where? That’s an impossible question to answer, as every forest garden will be different. However, there are a few guidelines to help you decide.

Forest gardens are usually divided into guilds, named for the tall tree that it will include. Each guild has up to seven layers within it: canopy tree, short tree, shrub, herbaceous, ground cover, roots and vines. You need to make sure that everything that is planted together is a companion. Some trees or plants add toxins to the soil that are poisonous to other plants, but there are always some that will tolerate it and can act as a filter to other guilds. For example, if you have a Juniper near your orchard that you don’t want to cut down, you will have to plant something like Mulberry, grapes, currants or Pomegranate next to it, as all of those are not affected by the Juniper’s toxins.

It helps to make a table with headings like: maximum height, width of canopy, temperature range, humidity range, soil preference, nitrogen fixer or feeder, companions and antagonists. Add any plant that you want to the list on the table, and fill out all the categories. There’s a lot of information out there on all kinds of options for your forest garden, but a fairly good place to start is pfaf.org

You want to mix and match your guilds, so that you balance out your tall trees and have a nitrogen fixer periodically. Include some plants that will survive extremes in temperature and humidity (weather is becoming increasingly unpredictable). Put sprawling trees like figs where you want a wind block, arbors with grapes where you want shade in summer but not winter (like over a bench), brambles like blackberries are great for hedges where you don’t want people or animals to walk.

Also, include your animals in the process; a forest garden can provide for a lot more than just you. What do your bees, rabbits, pigs like? There are many plants, like a Mulberry tree, whose leaves are edible to animals, so they end up being extra efficient food sources. You can also tractor your rabbits within the forest, so they can eat down grass and weeds, but also fertilize the soil (rabbit manure is an excellent fertilizer that can be placed on plants directly without burning them). If you have an area enclosed, you can put something like quail in there, to keep bugs down (not chickens, as they’ll scratch everything up and eat many of your plants). Do not, under any circumstances, let goats anywhere near your forest garden!

Don’t remove native trees or plants just because you might not want them in your longterm forest. Existing trees will offer shade and wind protection for tender, young plants, and the natives are already naturally adapted to your environment. You can always remove them later once things get established. Furthermore, there are many hardy weeds that are edible and tasty. Amaranth leaves, Lambs-quarters and purslane are frequent additions to our dinner salad, and many others besides are fed to our rabbits. Keeping some native weeds might also help with bug control; we noticed that grasshoppers always eat the wild amaranth first, so we started to cultivate it as a garden and orchard perimeter.

Bare in mind that many perennials take a long time to grow from seeds. If you haven’t yet found all the plants you want or your seeds haven’t grown enough, don’t be afraid to stick some annuals in there for the time being.