Compost Tea: What It Is and How to Use It in Your Garden
Compost tea is a natural liquid feed made by steeping mature compost in water. Many gardeners use compost tea to support soil health, encourage strong root growth, and add beneficial microorganisms to the garden. It is simple to make, inexpensive, and fits perfectly into an organic gardening approach. This works by extracting nutrients and living microbes from compost into a liquid form that can be poured onto soil or sprayed onto leaves.
Compost tea has become popular among gardeners who want a gentle, natural feed that improves soil life rather than relying on synthetic fertilisers. While results vary depending on compost quality and brewing method, compost tea remains a useful tool for gardeners who want to build long‑term soil fertility.
What Compost Tea Actually Is
Compost tea is water that has absorbed nutrients and beneficial microorganisms from high‑quality compost. When compost is mixed with water, the bacteria, fungi, and protozoa living in the compost move into the liquid. This creates a mild, plant‑friendly feed that can be used throughout the growing season.
There are two main types of compost tea that gardeners use.
Simple Soak Compost Tea
This is made by placing compost in a bucket of water and letting it steep for a day or two. The nutrients dissolve into the water, creating a gentle liquid feed suitable for most plants.
Aerated Compost Tea
This version uses an aquarium pump to add oxygen while the compost brews. The increased oxygen encourages beneficial microbes to multiply. Aerated compost tea is usually brewed for 24 to 36 hours and used immediately for best results.
Both types can be helpful, but aerated compost tea is often chosen by gardeners who want a more microbe‑rich solution.
Why Gardeners Use Compost Tea
Gardeners value compost tea for several reasons:
• It provides a natural, gentle feed • It supports soil structure and microbial life • It helps plants develop stronger root systems • It can be used on seedlings and young plants • It may help reduce some leaf problems when used as a foliar spray
Whilst it is not a miracle product, it can be a useful part of an organic gardening routine.
How to Make Compost Tea at Home
Making this at home is straightforward and requires only a few basic items.
What You Need
• Mature, fully finished compost • A bucket or container • Water that has been left to stand so chlorine can evaporate • A mesh bag or old pillowcase (optional) • An aquarium pump if you want to make it aerated
Step‑by‑Step Method
- Fill a bucket with water and let it sit for 12 to 24 hours to remove chlorine.
- Add a few large handfuls of compost directly into the water or place it inside a mesh bag.
- Stir well.
- For aerated compost tea, place an aquarium pump in the bucket and let it bubble for 24 to 36 hours.
- For simple compost tea, leave the mixture to steep for 24 to 48 hours, stirring occasionally.
- Strain the liquid if you plan to use it in a sprayer.
- Use immediately for best results.
The leftover compost can be added back to your compost heap or used as mulch.
How to Use Compost Tea in the Garden
Can be applied in two main ways.
Soil Drench
Pour directly around the base of plants. This helps feed the soil and supports root development. It is especially useful for seedlings, young plants, and crops growing in containers.
Foliar Spray
Spray onto the leaves of plants. Early morning or evening is best, as the liquid can dry too quickly in strong sunlight. Foliar spraying may help beneficial microbes settle on leaf surfaces.
When to Use Compost Tea
Used throughout the growing season. Many gardeners apply it:
• When planting out seedlings • During periods of active growth • After heavy rain • On container plants that need regular feeding
It is mild enough to use every two to four weeks.
