Are worm castings a complete fertilizer? | Solved!

Worm castings contain small amounts of nutrients that come from the broken down food scraps and organic matter that the worms digest. The worm castings contain a range of nutrients such as nitrogen, phosphorus, calcium and iron in small amounts. This is perfect for improving the soil and gently fertilizing plants.

Worm castings are not a complete fertilizer however for plants that are heavy feeders plants such as citrus, blueberries or plants suffering from deficiencies. These plants will usually need a specialized fertilizer to replace the nutrients used up when the produce large crops or to correct specific nutrient deficiencies.

If you are planning on growing an organic vegetable garden, worm castings are perfect for improving the soil. Mix through some pelleted chicken manure to add extra nitrogen to help with plant growth. A combination of worm castings, pelleted chicken manure and compost will make the perfect gentle fertilizer mix for most plants.

If you are growing citrus then they will benefit from additional trace elements and minerals each year. Worm castings will not be enough to replace the nutrients used up when producing fruit. Add a complete citrus fertilizer and worm castings as a top dressing to feed your citrus and improve the soil at the same time.

This article will explore all you need to know about the best ways to use worm castings in your garden to deliver gentle supply of nutrients, improve your soil bacteria balance and to increase the organic matter in your soil.

Top 6 ways to use worm castings in your garden

Worms digest the nutrients in the food scraps and organic matter making them easier for the plants to absorb. The worm castings will also contain lots of good bacteria which will help to improve your soil over time. Here are my favorite ways to use worm casting in your garden at home.

1. When planting new seedlings

Worm castings are a great way to fertilize new seedlings when planting them into your vegetable patch or garden beds. You can mix a small handful of worm castings into the soil when you plant each seedling or mix it through your vegetable patch at the end of each season.

I like to add plenty of worm castings after I have been growing tomatoes, peppers and herbs over summer. These plants use up lots of nutrients as they grow and worm castings are a great way to replace them. Adding worm castings 2 times per year will help to replace nutrients and prepare the soil for your next crop.

2. To improve seed raising mix

Add a small amount of worm castings to improve your seed raising mix. Seed raising mixes generally will not contain any fertilizers as they are designed to support the seeds first few weeks of growth. Improving seed raising mix with worm castings means that the soil can support plant growth for longer and you won’t have to transplant your seeds as early.

Worm castings will support the seedlings to grow larger in the pot before you need to plant them out, minimizing root disturbance. If you use a taller pot to raise your seeds and add worm castings you can let them grow to 4-5 inches before planting them out.

These seedlings are growing in a mix with added worm castings.

3. Make a liquid soil improver

Worm castings are perfect for adding to the soil in liquid form to gently feed your plants and soil. Place 2-3 handfuls of worm castings in a stocking and let it soak in a bucket for 2-3 hours. This will draw out the nutrients and good bacteria while leaving the larger particles behind. You can then water this onto your garden and soil using a watering can.

Another method is to add 1-2 cups of worm casting straight into a bucket of water. Stir it around and pour it straight onto the root zone of the plants and soil. This way you get to capture all of the organic matter and return it to your garden. This is the method I use throughout spring to give my plants an extra boost of nutrients.

Using this method is a great way to avoid disturbing your worms. You can gently remove 2-3 scoops of castings without upsetting your worm colony.

4. To improve potting soil

Worm castings are great for improving potting soil. Even a small cup full to a whole bag of potting soil will improve plant growth. Adding worm castings will add nutrients, improve the water holding capacity and healthy soil bacteria.

5. When planting new fruit trees

Adding worm castings to the ground soil when planting new fruit trees is a great way to give them the best start. Using a garden fork, work around 1-2 shovels of worm castings into a 3-4 square foot area where you are growing your new tree. Gently dig it into the top foot of soil, in a dish shape, digging it in deeper in the middle.

This will help to lighten the soil, improve drainage, feed the plant and add healthy soil bacteria.

My new mango tree with added worm castings.

6. To improve vegetable garden soil

At the end of each season add worm castings to your vegetable garden to improve your soil for the next crop. Remove the old crop and gently dig through a few cups of worm castings, aged cow manure and compost. You can also sprinkle some pelleted chicken manure to add extra nitrogen.

Allow this mix to settle in for around 2 weeks before planting anything new. This will help the nutrients to be broken down and incorporated into the soil before you plant your next crop of vegetables. This mix is perfect for summer and winter vegetables like broccoli, cauliflower, tomatoes, peppers, cucumbers, beans and herbs such as basil, parsley and chives.

My peppers are growing huge with worm castings.

Are worm castings a complete fertilizer? | Summary

Worm castings contain small amounts of nutrients so are not a complete fertilizer for plants that require a lot of nutrients to replace those used up when producing fruit. This includes lemons, limes, oranges, mandarins, tangelo, blueberries, mangoes or any plants with a deficiency. These will need specialized products to replace the nutrients used up when producing fruit or to add back a specific nutrient they are lacking.

Use worm castings regularly in your garden to improve the soil health overall, feed the worms and soil bacteria and add a gentle feed of nutrients.