Soil Prep for the Vegetable Garden

Adding plenty of compost and aged manure will get your vegetable garden off to a great start

True gardeners rarely refer to soil as simply dirt. They understand the difference between the stuff you dig up in your backyard versus the “black gold” that consist of compost, manure, decomposed organic matter and millions of beneficial microbes that are actively at work underground.

Fortunately, converting dirt to soil is an easy process. Within this context, understanding three commonly used gardening terms – texture, structure, and tilth – should help clear up one of the dirtier mysteries of gardening.

Let’s start with soil texture. Texture refers to the relative percentage of sand, silt and clay within the dirt. Ideally, you want to have an equal amount of each. When these three are proportionate, the soil is said to be loamy. Soil with great texture allows plant roots to spread, moisture to be retained (but not to excess) and essential air pockets to exist between the tiny spaces of the soil particles.

Next is soil structure. Simply put, structure is how sand, silt and clay fit together. Good structure is evident when the soil holds together if squeezed, but breaks apart or crumbles easily when disturbed. As I work to achieve ideal soil structure, I am constantly working to blend the right amounts sand, silt and clay to get the results I described above.

In my North Carolina garden, (which was mostly clay) I usually find adding plenty of compost and aged manure do the trick. The compost is home made. However, the cow manure is another story. Since I live in a suburban neighborhood, a pasture of cows or stable of horses is not an option. Fortunately, composted manure is available by the bag at many garden centers and home improvement stores.

But all bagged manure is not the same! Many contain fillers and are inferior in quality. I’ve had great results with Black Kow composted cow manure because it’s pure composted manure. It cost a bit more per bag but, as with most things in life, you get what you pay for. Unfortunately, it is not available outside the southeast.

When soil has good tilth, it drains well. It is loose enough to allow for adequate drainage, yet dense enough to retain moisture long enough for plant roots to utilize it. This is why garden soil should neither contain too much sand or too much clay.

The key is to know from which extreme you are starting. If soil is too dense, then your action is to loosen it up by adding gritty organic material like composted bark. For soils that are too loose, you want to increase the water holding capacity. Sphagnum peat moss is an option for this. However, in either case, organic material continues to break down over time. Monitor your soil constantly, and amend when needed.

Understanding what makes perfect soil will get you well on your way to having the best garden ever. Regardless of your current soil texture, structure or tilth, you can change what you already have. Call it a soil makeover. By adding organic material like compost, humus, composted cow manure, leaf mulch, peat moss, etc. – and a bit of persistence – you can greatly improve your soil.


Joe Lamp'l is the Host and Executive Producer of the award winning PBS television series Growing A Greener World. Off camera, Joe dedicates his time to promoting sustainability through his popular books, Compost Confidential blog, podcast series, and nationally syndicated newspaper columns. Follow Joe on Twitter

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  1. Renea says

    I am trying to prepare my lawn for an organic vegetable garden in the spring. I didn’t want to till so I put down cardboard with straw and some topsoil to kill the grass. Is this a waste of time? What do you recommend? Should I just wait till early next year to prepare the lawn?

    • says

      Definitely not a waste of time to start now preparing your space for next spring’s organic garden. You need time to smother and kill the area and it can take months. What you are doing now is a great way to soften the area, improve the soil biology and preserve the soil integrity by not tilling. Good for you Renea.

  2. James says

    I live in East Texas and have sandy soil for my vegtable garden. How much area will a 40 pound bag of cow/humus/compost cover? My garden is about 3,200 sq. ft. Will 150 bags be sufficient?

    • says

      James, do a web search for “soil calculator” Pick one of the options. It will likely bring up an easy to fill in blanks based on the square footage of your garden and the depth of soil you would like. It should tell you in cubic yards and feet, how much soil you need to add.

  3. says

    I planted some Hibiscus flowers about 3 gallon size here in South Florida. We added Black Kow to the holes and watered them and backfilled . Just wondering if I should of added peat moss also . ?

    • says

      Peat moss will help retain moisture and if you are going to add it, should be incorporated into the entire soil mix before planting. In native soils that drain too quickly, peat moss can help. However, Hibiscus does well in south Florida in native soil without peat so I would not go back and change anything now. You should be fine as long as you water sufficiently until the roots are established. Then the plants should do fine from there as is.

  4. Julia says

    Can Black Kow be added to the soil after vegetable garden has been planted? My tomatoes, peppers, okra, etc are not growing? Thanks

    • says

      I love Black Kow and yes, you can add it any time. It’s a great soil amendment in my opinion and safe to add before, during and after plants are in the ground.

  5. Tom Calabro says

    we are planing on growing a sqaure floot vegetable garden,
    and we live in florida with very sandy soil, i have 2 x 6 x 3 lumber ruff cut pine from dunage, to starting a raised grden
    i was figuring to use black kow to either mix with or have dirt brought in to mix with black kow to start garden
    now im from MI and there was never a problem to plant , but florida is quite different soil set up
    so how to proceed is my main question , as far as soil make up and what to mix and how much, i have in past days in Mi used 100% compost from a horse farm and boy did it grow ,but ive been told that the area im in has low nutriants in soil also
    any and all opinions are welcome

    • says

      Tom, Black Kow is a favorite product of mine. But I always like to create a blend of several inputs to create a more diverse soil. Consider adding compost (purchased in bag or bulk), shredded leaves, bagged mulch, mushroom compost, etc. Be careful about using manure from horse farms. A huge problem these days is a persistent herbicide that is sprayed on hay that horses then eat. The herbicide does NOT break down quickly and can kill your plants in your vegetable garden when used as compost. If you want to learn more about this, search “killer compost” on our site for a lot more details on my own experience with this in my garden. Good luck.

    • says

      Hi Kt. I think so. I’ve never tried it but I think you should be fine. You just need a clean soil environment that drains well for your seeds. Black Kow is a great product. It drains well, which is important for seed starting. The biggest concern that I can see is the potential for burning the tender young plants based on the nutrient content in the soil. But as an organic, composted product, the nutrient analysis is very low (0.5-0.5-0.5) so I don’t see any risk of burning. Please do us all a favor and give it a try. Then report back. I know we would all appreciate learning through your experience.

  6. says

    What is the best way to spread black kow over my cencentipede lawn? Tried using a Scott spreader which seemed like a great idea, but to no avail. Help!

    • says

      Great product choice Shelly. I wish I knew of an easy way to spread it. Since it comes in bags, I would slit the bag at the top and walk it around your lawn as it spilled out as evenly as possible. Then take a steel tined rake or a grading rake and turn it upside down. Use the flat back side to knock down and smooth out the clumps. The back side of these rakes is an underutilized method by home gardeners to easily smooth out and distribute soil, just as you are describing. Good luck and great question.

  7. Lindsey says

    I live in Michigan, and my husband and I are first time gardeners. The area we cleared out for our garden was once part of our gravel driveway, and therefore, we have no dirt to start with. What would you recommend starting with to form a base for our soil? Everything I find assumes that there is dirt available to add to, which is not the case for us.

  8. Susan says

    How soon after doing this can you plant an edible garden? A week? I have been told one week. I read several months. Do you know? Can you tell me?

    • says

      Once the soil is prepped, plant away Susan. No reason to wait if it’s based on what I suggested in my post. The only reason I can see waiting is if you were to put down and herbicide to kill off any weeds. In that case, yes, waiting a week is smart. But as an organic gardener, that’s not an issue with me. Once I amend the soil, it’s time to plant.

  9. Robin Howard says

    I live in south Georgia, and this is the first article I have come across in my search that talks about the construct of the southern soil. Thank you! I feel confident in my mixture of black kow sand and clay now…..just waiting for the weather to behave

  10. Sunny Peterson says

    I like the way you start — preparation of the earth. Perhaps instead of depleting sphagnum peat moss supply, you could suggest more soil builders that are right under our noses or near by like leaves (lots of folks put them out for trash pick up), pine needles, seaweed, manure from a riding school, wood shavings, chipped wood from tree service companies and don’t forget that some counties make mulch and let folds pick it up for free.

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