Amending Soil: Preparing Your Garden Before Planting

Healthy soil is the foundation of productive plants, and amending soil regularly is one of the best ways to ensure bountiful harvests. Whether starting a spring, summer, or fall garden, amending soil before planting can make all the difference in your garden’s success. Follow these five steps to help your garden beds thrive season after season.

Article Index:

1. Examine Existing Beds
2. Evaluate the Soil
   • Why Not Till?
3. Amend your Soil by Adding Compost
4. Prepare Your Soil for Planting by Adding Worm Castings
5. Add Other Needed Amendments to Prepare Your Soil for Planting

1. Examine Existing Beds

Begin by doing a quick visual assessment of your garden beds:

• Raised Bed Condition
  • Do the sides need any repairs?
  • Are there gaps or signs of rotting wood or weakened materials?
• Irrigation Check
  • Is your watering system functioning correctly?
  • Are there any leaks, clogged emitters, or areas not receiving adequate moisture?
  • Is the coverage sufficient for all plants?

If you need to update or replace your beds, I highly recommend the metal raised beds and watering grids from Garden in Minutes. I’ve used them in my own garden for years, and they’ve been incredibly durable and easy to maintain. Plus, the watering grids ensure even moisture for your plants. Use code Angela10 to save $10 off $100, or GITG5 to save 5% on any size order.

2. Evaluate the Soil

Once your beds are structurally sound, shift focus to the soil itself:

• Soil Level & Texture
  • Has the soil level dropped significantly? Consider whether you need to top off with fresh raised bed mix or if a layer of compost would suffice.
  • Is the soil still loose and friable? If it feels compacted or you notice a drastic change in texture, supplementing with components like coconut coir, vermiculite, or a raised bed mix that includes those may be necessary. I use the raised bed mix from Arizona Worm Farm. Learn more about this soil mixture here.

• Weeds, Diseases & Pest History
  • Were there major weed issues, diseases, or pest infestations last season? If so, remove any remaining plant debris or weeds to prevent carry-over problems. If Bermuda grass is an issue, read this guide.
• Soil Testing
  • If your garden is growing well, this step may not be necessary. But if plants have struggled or not grown well a soil test is a good way to see what is going on.
  • Soil pH & Nutrient Levels: A soil test is the best way to know precisely what amendments your garden needs. You’ll learn about nutrient deficiencies (nitrogen, phosphorus, potassium, and micronutrients) and whether pH adjustments are necessary.
  • Use a reliable, easy-to-read soil test kit or send samples to a local extension office for professional analysis. This is the soil test kit I use.
  • Follow test recommendations to address any imbalances before you plant. Learn more about how to test your soil in this guide.

Tip: Don’t till your soil. Tilling disturbs the good things that are happening in your soil!

Why Not Till?

• Preserves Soil Structure
  Tilling can break apart soil aggregates and damage fragile networks of fungi and microorganisms. Undisturbed soil holds water and nutrients more effectively.
• Protects Beneficial Organisms
  Earthworms, microbes, and other helpful creatures thrive when left undisturbed. These organisms improve soil fertility by breaking down organic matter and making nutrients available to plants.
• Reduces Weed Pressure
  Tilling can expose dormant weed seeds to sunlight, causing them to germinate. Leaving the soil undisturbed helps keep those seeds buried and less likely to sprout.
• Prevents Erosion
  Soil with a stable, undisturbed structure is less prone to wind and water erosion, helping maintain soil depth and quality over time.

By minimizing disturbance and simply layering organic matter (like compost) on top, you enhance your soil’s natural processes—resulting in healthier, more resilient garden beds.

3. Amend your Soil by Adding Compost

One of the most essential steps in amending soil is adding compost. Compost is a cornerstone amendment for any garden.

• Benefits of Compost
  • Improves Soil Structure: Loosens heavy clay and helps sandy soils hold moisture.
  • Adds Nutrients: Contains essential plant nutrients like nitrogen, phosphorus, and potassium, plus beneficial micronutrients.
  • Boosts Beneficial Organisms: Feeds microbes and earthworms that help make nutrients more available to plants.
  • Reduces Diseases & Pests: Compost can help suppress some plant diseases and pests.
  • Enhances Moisture Retention: Helps the soil hold water, reducing the need for frequent watering.
• How to Add Compost
  • Layer, Don’t Till: Spread at least one inch (2.54 cm) of compost on top of your soil. Earthworms and microbes will integrate it naturally.
  • Dealing with Mulch: If you have a thick mulch layer, pull it back, add compost, and then replace or refresh the mulch as needed.
• Which Compost to Use
  • Homemade: Homemade compost is best if you can make it. Learn how to make compost in this guide.
  • Locally Sourced: A local, trusted compost supplier is your next-best option.
  • Store-Bought: If using bagged compost, buy multiple brands for a varied nutrient profile.

4. Prepare Your Soil for Planting by Adding Worm Castings

Worm castings are a powerful, natural soil amendment:

• Why Use Worm Castings?
  • Naturally high in beneficial microbes and nutrients.
  • Gentle, slow release of fertility that won’t burn plants if applied correctly.
• How Much to Add
  • For established beds, apply 4 cups per 4×8 bed.
  • In new beds, aim for around 5% worm castings (11 gallons per 4×8 bed).
  • Layer them on top of the soil and lightly water them in.
• In-Bed Vermicomposting
  • Add an in-bed vermicomposting bin for an ongoing supply of worm castings directly in your raised bed. It’s a low-maintenance way of amending soil throughout the growing season. Learn how to add vermicomposting bins to your garden here.

To learn more about the benefits of worm castings, read this guide by Zach Brooks of Arizona Worm Farm.

Tip: Apply 4 cups fresh worm castings to each 4×8 raised bed each season.

5. Add Other Needed Amendments to Prepare Your Soil for Planting

Although I add compost and worm castings each season, I don’t always add other amendments. You can finalize your plan for amending soil based on your soil test results. Consider these common soil amendments:

1. Biochar (link to purchase)
   • Improves soil texture and water retention.
   • It acts like a sponge, holding nutrients until plants need them.
   • It can raise pH, so be mindful if your soil is already alkaline.
2. Azomite (Rock Dust) (link to purchase)
   • Rich in minerals and trace elements that garden soil may lack.
   • Useful for amending soil that has been heavily used or depleted.
3. Gypsum (Calcium Sulfate) (link to purchase)
   • Beneficial for clay or compacted soils.
   • Helps loosen particles and improve drainage.
4. Blood Meal (link to purchase)
   • Quick source of nitrogen.
   • Follow label instructions to avoid over-fertilization.
5. Bone Meal (link to purchase)
   • Adds phosphorus for strong root growth and flower/fruit production.
   • Also provides calcium and some nitrogen.
6. Kelp Meal/Seaweed Extract (link to purchase)
   • Offers micronutrients, natural growth hormones, and stress resistance.
   • Great for amending soil to support seed germination and root development.
7. Green Sand or Langbeinite (link to purchase)
   • Green sand supplies potassium and micronutrients.
   • Langbeinite delivers potassium, magnesium, and sulfur—excellent if your test indicates shortages.

Tip: Always adhere to recommended application rates when amending soil, as over-amending can cause nutrient imbalances.

Final Thoughts

Taking the time at the beginning of each season to prepare garden soil before planting pays off by reducing problems later on and boosting plant performance. By layering amendments like compost and worm castings, adding specific nutrients based on a soil test, and avoiding deep tilling, you’ll keep your soil structure healthy and full of beneficial organisms.

Healthy soil is a living ecosystem. With consistent care and careful amending of soil, your garden will become more productive and resilient each season—setting the stage for vigorous plants, fewer pest problems, and delicious, abundant harvests.

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