Early spring is an ideal time to do some soil maintenance in your garden. Each year, I modify my technique based on new things I learn. In the past, I’ve raked finished compost into the surface of our soil, but this year I decided to experiment with a different method, double digging.
I first practiced double digging last May, when I had the opportunity to study with the head gardener at Hollyhock, Holly Mackay. At the Hollyhock garden, beds are dug each year, resulting in a lush oasis that feeds their many guests. The idea behind this technique is simple: get the nutrients down under the surface of the soil, where plants actually need them. I had been reluctant to try double digging in the past because it’s more work than adding compost to the top of your soil, and some gardeners believe that it’s not good to disturb your soil structure. But after learning that it’s part of Hollyhock’s magic, I knew I had to give it a try. Double digging aerates the soil beautifully. It keeps pathogens from newly introduced amendments buried and helps to create a fine-textured, seed-friendly soil at the surface. Here is a step by step guide to how we prepared our 4’ by 8’ beds this spring.
Step 1: Gather your resources
Start by deciding what you’ll be using to enrich our soil. Finished homemade compost is great if you have it handy. Alternately, bagged organic compost or “soil enricher” can be purchased from a reputable soil supplier or garden store. Aged manure can be a powerful way to increase soil fertility as long as you keep safety considerations in mind. This year, because our soil was in pretty good shape and just needed a little boost, I used Sea Soil, available from many garden supply stores. Each of these amendments has its own unique properties, though I’ve found that as long as you are starting out with fairly decent soil in your bed, the most important thing is to just make sure that you’re adding something.
You’ll also need a wheelbarrow, a shovel, a hard rake, sturdy shoes and granulated organic fertilizer.
Keep in mind that double digging can be hard on your back (and it’s a serious workout). If you have any type of injury or health consideration, get someone else to do the work for you. Personally, my husband and dad did almost all of the heavy lifting.
Step 2: Clean your bed
If you have low tunnels or other garden structures on your bed, start by taking them off. Remove all weeds, overwintered plants, labels and twine from your bed. You want to get things down to a blank slate.
Step 3: Dig the first trench
Dig a trench, about the same depth and width as your shovel, across one end of your bed. Toss the contents of this trench into your wheelbarrow, which should be placed near you.
Step 4: Add your amendment
Spread an even layer of your chosen amendment, about one to two inches thick, across the bottom of the trench.
Step 5: Dig the second trench
Dig your second trench right next to the first one. This time, toss the soil you displace into the first trench, filling it up.
Step 6: Repeat steps 4 and 5
Keep digging trenches and adding your amendment until you’ve reach the other end of your bed. Along the way, remove any rocks, roots or debris you encounter.
Step 7: Fill in the final trench
Use the contents of your wheelbarrow to fill in the final trench.
Step 8: Even it out
You’ll now have a fluffy mound of soil. Use a hard rake to even it out, breaking up any lumps as you go. Make sure you don’t step on your soil at this stage! Your soil will be aerated and the soil level will be much higher than when you started.
Step 9: Add granulated organic fertilizer
To boost micronutrients and give the surface of your soil a kick, top things off with a sprinkle of slow-release, general purpose organic granulated fertilizer. I use Gaia All-Purpose 4-4-4 fertilizer blend. Wear a mask when handling granulated fertilizer, as it can be quite dusty. Toss a thin, even layer over your bed. Give things a once-over with your rake to incorporate the fertilizer into the soil.
Step 10: Add garden structures
Now’s a good time to add drip or soaker hose irrigation lines. After last year’s drought, I’m not taking any chances: I want to have my irrigation in place before I plant anything. We also added twine to mark out modified square foot garden blocks: our bed frames have nails every twelve inches, and each square will be home to one planting of seeds. Finally, we replaced the hoop structures that cover our beds.
You can start planting right away, though personally I like to give newly prepared beds a week or two to rest so that newly added nutrients can get incorporated and newly introduced pathogens can dissipate.
We finished things off by covering our beds up with lightweight floating row cover material. This multipurpose stuff prevents soil from washing away, warms the soil and keeps bugs out. I like to place it right on top of newly planted seeds, as I find that it really increases germination. Another big advantage of row cover is that it can help deter cats, who sometimes use newly dug beds as litter boxes – a big problem because their droppings can contain toxoplasmosis gondii, a harmful parasite.
This technique feels like a lot of work, but you only have to do it once a year. It’s satisfying to know that our soil has been well prepared and is ready for the spring.