Although organic gardeners have been using worm casts for years, including our affiliated partner Charles Dowding, the wider gardening community is only now beginning to learn about their fantastic benefits for plants.
Many of you have asked us here at Urban Wyrm whether worm castings are good for all plants - and the short answer is yes! Read on to find out how plants benefit from the organic goodness of worm casts and how you should use them.
What plants benefit from worm castings?
Nearly all plants can benefit from the nutrient-rich, microbe-packed qualities of worm castings. Whether you’re growing vegetables, flowers, herbs or houseplants, adding worm castings can make a noticeable difference in health, growth and resilience. For vegetables and fruit-bearing plants, our studies on Urban Wyrm worm castings have been shown to increase yields up to 8 times bigger!
Worm castings are also versatile enough for every part of your garden, from beds and borders to containers and hanging baskets. Their pH-neutral quality means they’re safe for acid-loving plants like tomatoes and hydrangeas, as well as more pH-sensitive varieties like azaleas and rhododendrons.
Plus, worm castings have been proven to suppress both soil-borne and foliar diseases, including pythium and botrytis. Dr Clive Edwards at the University of Ohio found that vermicompost (worm compost) proved that the microbial power of worm casts helps to prevent disease in plants.
How to use worm castings in your garden
There are several ways to incorporate worm castings into your gardening routine, and each method supports different stages of plant growth:
- Seedling mix: Mix worm castings with seed compost at a 1:5 ratio, or sow your seeds straight into 1cm of worm casts. This gentle environment supports early root development, helping young plants get a strong start.
- Mix with potting soil: For general planting or repotting, mix worm castings at a ratio of 1:5 with potting soil. This creates a nutrient-rich base that supports root growth and supplies plants with nutrients over time. Save time and simply use our Black Gold Organic compost, which is already enriched with Urban Wyrm worm castings.
- Top dressing: To give an extra boost to established plants, sprinkle a thin layer of worm castings around the base. Nutrients will seep into the soil with each watering, providing a gentle, slow-release feed.
- Worm tea: Worm tea is an easy and effective way to water plants with a high-potency feed. Steep a handful of worm castings in a watering can for 24 hours, the water both your indoor and outdoor plants.
How long does it take worm castings to break down in soil?
Worm castings break down slowly, providing a sustained nutrient release that lasts several months. Essentially, they act as a slow-release fertiliser, so plants receive nutrients over time rather than all at once. This steady breakdown helps maintain soil fertility, meaning plants experience more consistent growth without the risk of fertiliser burn or nutrient overdose.
While the castings themselves last several months, their impact on soil health can last much longer. The beneficial bacteria, fungi and humic substances in worm castings continue to improve soil structure, water retention and root health, leading to a cumulative boost in soil vitality with regular use.
Can you add too many worm castings?
Worm castings are incredibly gentle on plants, making it difficult to overdo it. They’re pH-neutral and free from harmful chemicals, so even if you add more than recommended, plants are unlikely to suffer adverse effects.
However, for optimal results, it’s best to follow usage guidelines to ensure plants receive a balanced supply of nutrients without wastage. Mixing worm castings with regular compost or soil creates an ideal growing medium that enhances growth without overwhelming plants.
So overall, worm castings are a highly adaptable and effective addition to any gardener’s toolkit. Whether you’re a seasoned grower or a beginner, incorporating worm castings can help you cultivate healthier plants, boost yields, and reduce dependency on synthetic fertilisers, all while supporting sustainable gardening practices.
Try Urban Wyrm’s pure worm cast pouches and see how much of a difference they can make in your garden.
