For us, productive beds are double-dug and covered with insect netting in the warm seasons, and with additional protection of Agribon in the winter. They are well-watered and have lots of organic material. It is also helpful to have some clay in the soil. Extremely sandy soil loses moisture very fast. If your soil is nearly all sand, you can improve it with compost and other organic materials,
We refuse to use any chemical fertilizers or pesticides (except for a few bio-controls approved for organic use), so we are constantly improving the soil rather than depleting it.
The desert environment is challenging in many ways:
- Day-Night temperature swings
- Furry critters that like seedlings
- 6-legged critters that like nearly everything (grasshoppers, etc.)
- Hot, dry winds, sometimes very strong
- Lots of hungry desert birds.
- Intense sun of high elevation (high desert)
The insect netting helps minimize all of the above to some degree. It helps considerably to block the wind, preserves moisture a bit, shades a bit and eliminates about 95% of all insect pests (some beetles live in the ground and so are already there when you install the netting).
Preparing the garden beds
John Jeavons wrote a book (it's a gardening classic): How to Grow More Vegetables.... We use his method of double-digging. This makes sure rocks are out of the beds, allows a large storage of water in the space between soil particles.
Compost or some sort of organic material is critical for success. Backyard Market Gardening claims a yield of up to 31 times higher for adequately amended soil, compared to unamended soil, and we have seen dramatic differences at SGS as well. In the desert, it's even more important for the water storage value, in addition to nutrients and proper tilth.
How wide should the beds be?
After experimenting with different widths, we have found 3 1/2 feet (42 inches) to be the ideal width, at least in the part of the world that uses feet and inches. Three and one-half feet is the magic width because it provides adequate height for most vegetables to grow when using 1/3 sections (80 inches) of a 20' PVC pipe for hoops. Exceptions are tomatoes and other high-growing vegetables which we are experimenting growing in double-wide hoops which span two rows and are slightly over 6 feet tall. These are more susceptable to wind damage but have the advantage of walk-in convenience without removing the cover.
How long should the beds be?
This depends on you, your available space, etc. Our beds are 18 to 25 feet long. 20 feet is a good medium length. In this range, it's not too time-consuming to walk around the end of the bed to get to the other side. A few strides and you are there.
Laying out your beds before starting to dig
Some books recommend laying out your beds in a North-South direction (ends facing north and south). However, we find that East-West alignment works just fine for us. We put 2 foot pathways between the 3 1/2 foot beds. Using some of the 1 foot rebar (see below) and some string, string two lines lengthwise to lay out the bed. You can do this one bed at a time as you go and just keep moving the strings. Leave about 6" to 1 foot extra on each end so that when you dig the bed the rebar is still firmly in the earth. If you put the rebar right on the corner of the bed, it will fall in or badly loosen.
Digging your beds
We follow the Jeavons method as mentioned earlier, but because we are in a very rocky area, we also filter all the rocks out using 1/2" hardware cloth. This allows the harmless pea gravel to fall through, and eliminates all the annoying larger rocks. We use the filtered rocks for dirt road repair, embankment stabilization, rings around trees, rock and mortar construction, etc. Notice how we have placed plywood strips along the 2-foot path area, so we can just dump the filtered dirt in the hole which collects in the path. A very small amount lands in the adjacent bed, which is normally not a problem.
A big helper is soaking the lower level before digging it. This will make the spading fork slide in much easier. Otherwise you will have to use a pick on every square inch if you have hardpan or lots of rocks. I try to use the pick as little as possible. But you have to be careful not to lever the tines on the spading fork too much -- they are very easy to break!
Be patient with yourself as you dig the beds. This is sometimes very hard and slow work in desert soil. Just remind yourself this is the last time you will need to double-dig THIS bed if you maintain it well.
Adding organic material
Compost is the best if you have it. We use composted manure as one of our primary amendments because manure easily available in large quantities for free near us, and manure composts quickly. We just have to collect it, soak it, and pile it up. There never seems to be enough compost for our garden beds, no matter what we do, without purchasing some also. We purchase organic compost and peat moss when we need to. There just isn't as much organic material in desert environments. But, in most desert areas there are horse lovers that are happy to have you come and clean out their stables, as well as free-range cattle that deposit most of their manure near their "hang-out" spots. A pickup truck or trailer is very useful, as are flat shovels. For small amounts you can use 5-gallon buckets and haul it in any car or truck. You may also want to wear a mask and goggles to keep horse manure out of your nose and eyes on hot, dry, windy days. Horse manure has done wonders for our garden. When collecting cow manure more than 2 days old, it's easiest to just pick it up with rubber-coated gloves than trying to shovel it.
We use diluted activated EM-1 to speed up decomposition and kill any possible pathogens, which are unlikely but possible. The Soul of Soil (a book every gardener and farmer should have) recommends piles of 5'X5'X4' high as ideal for best composting.
Recently, we expanded the garden a little too fast and ran out of compost, and we can really tell the difference when we don't add sufficient material. I recommend about one wheelbarrow load for every four feet of bed for new beds. We put about 1/4 in the bottom layer and 3/4 in the top layer of the bed (each layer is one foot deep) when we dig the bed. When replanting, an inch of added material is usually sufficient to keep the organic component of the soil "charged up", if the bed has been properly amended to begin with.
How to protect your beds
We use insect netting with PVC hoops secured by rebar. for a 20' bed, you will need the following
- Two 20' 1/2" PVC Shedule 40 pipe cut into 3rds (80 inch segments). This provides 6 pieces for proper spacing
- 30' of insect netting at least 7' wide (7 1/2' is ideal). We buy Smart Net (see below for details)
- 30' of Agribon for winter use (if you only grow during the no-frost season, you don't need this). This product at Johnny's will cover 8 beds. This is experimental with 80 inch hoops (see below).
- 12 feet of 3/8" steel rebar cut into 1 foot lengths
Smart Net Insect Netting Ordering Information
Details about the netting and the pricing are at THIS LINK. This is where you want to order it from if you live in Canada. If you live in the 48 US States, you will want to order from OESCO, which is located in Massachusetts. The product and price is the same, but the shipping will likely be less. You will have to order by phone. We did massive searches on the Internet and this is what we came up with. If you find a comparable product for a better price, register or log in and leave us a comment, or use the Contact Page. Note: if you buy the 15' wide netting, you can cut it in two to make 7 1/2 feet which is the perfect width for 80 inch hoops, providing sufficient overlap.
Assembling the Row Covers
- Cut rebar to one-foot lengths using a large bolt cutter or electric grinder with a cutting blade, if you didn't buy them pre-cut. Note: portable electric grinders are a great tool to have on hand around the garden and only cost about $30. If you can't afford it, ask to borrow one from a friend.
- Using the digging string lines as guides, evenly space the 12 rebar pieces roughly 4 feet apart, and just inside the string, 6 on each side. They should slide in easily if on the inside edge of your pre-dug garden bed. If not, you can use a hammer or small sledge. Push them in about 3/4 of the way, so just a few inches are sticking up.
- Place the PVC pipe over one rebar and bend it carefully over to the rebar on the other side of the bed. Repeat this for each of the additional 5 hoops.
- Dig a trench 4 to 6 inches deep on the side which the wind comes from most often (for us it is the South side)
- Cut netting to length so that you have about 1 foot overlap on each end on the ground after covering the ends. Cut carefully unless you know a good seamstress that will sew it back for you.
- Place netting over hoops and place the overlap on the windward side in the trench you dug in step 4.
Make sure you have enough overlap on the other side -- you should have at least 4 inches excess (8 inches preferred) laying on the ground when you stretch it tight.
- Bury the windward side.
- Place rocks, bricks, or boards on the leeward side and ends to hold the cloth down. The leeward side is the side you will open when tending the bed.
- When opening the bed, gently remove the weights so as not to damage the cloth, and roll it up on the windward side where it is buried, and weight down the rolled-up material. There is no need to un-bury the windward side. When done tending the bed, repeat step 8.
Keeping the beds warm in the Winter
The 83" wide Agribon is barely wide enough to cover the hoops with only a few inches to spare. We used this width on 60-inch hoops with 3 foot beds last winter, so I'm hoping that by putting the insect netting over the Agribon, it will keep it in place without burying or weighting down the Agribon. We will experiment with this in the coming Winter and blog our findings.
Maintaining your beds
You can hand-water using a wide sprayer hose attachment as recommended by Jeavons. If you have just a few beds this is a relaxing pastime. If you have 18 or more beds like we do, it's not going to be fun after a while, so use soaker hose or a sprinkler system. The 1/4" spongy soaker hoses get clogged from minerals in the desert. They can be bent frequently to get them dripping again, but this is tedious and time-consuming. They also tend to get in the way when you are tending the bed. Therefore we have switched to sprinklers that connect to the 1/4" drip distribution tubing, and they are working fairly well. Once we have all the kinks worked out of our system, I'll write another blog on this topic.
A soil test kit is available at most hardware stores and garden supply retailers, and should be used to test for NPK (Nitrogen/Phosphate/Potassium) as well as pH (acidity-alkalinity). Crushed phosphate rock can be used to boost phosphate over time. It is very slow releasing so you don't need to add it very often. Check the Jeavons book mentioned above for more ideas on balancing the essential nutrients. Compost is usually balances pH and adds the other nutrients. Animal manures are also great, but be careful with high-nitrogen manures -- use judiciously
We are also using the chicken tractor after digging a new bed and between crops (see cage structure in background of the above image)
Also, whenever we re-dig the beds (which takes only a few minutes) we add generous quantities of horse manure (and compost if we have it) again to the top layer. We also add horse manure as a top dressing which we carefully place on the soil between plants. This really helps cut down on evaporation.
Note: If you are in a place that has old buildings that may have been painted with lead-based paint, you should have your soil tested for lead.
Weeds suck a lot of water and nutrition from the soil and can also shade out your crops. It's important to regularly weed your beds. Fortunately double-dug beds with lots of organic matter make weeding easier. It's good to weed about two weeks after planting, then check regularly and weed when needed.