Compost Tea: The Complete Walkthrough

This guide covers compost tea, rated an easy task, typically taking 24–48 hrs.

This is the expanded version of our compost tea guide, for anyone who wants the full detail rather than just the quick-reference card.

Before the step-by-step detail, here's why this is worth learning in the first place. At a glance, it's rated easy, with a difficulty of easy; time of 24–48 hrs; cost of low — details that matter more once you're actually planning around them than they do on a first read. The rest of this article works through exactly what each of those means day to day, in more depth than a single printable card has room for, and with the reasoning behind each recommendation rather than just the recommendation itself.

How This Applies Across Property Types

This skill applies whether you're working with a suburban block or a larger rural property, though the scale and specific materials will differ. Where climate or regional conditions change the approach, that's called out in the method above rather than assumed — but as a general rule, Australian conditions (heat, water restrictions in many areas, and UV exposure on materials left outdoors) are worth factoring in even where a source guide doesn't explicitly mention them.

Steeped, not boiled

Compost tea is simply finished compost steeped in water to extract soluble nutrients and beneficial microbes, then applied as a liquid feed — a fast way to deliver a nutrient boost compared to solid compost.

What You'll Need

Keep these points in mind:

• Finished, mature compost or worm castings
• A bucket or barrel
• A porous bag or old pillowcase to hold the compost (optional but keeps it strainable)
• An aquarium pump for aeration (optional, improves quality)

Each of these compounds over a season — small misses early tend to show up later — finished, mature compost or worm castings An aquarium pump for aeration (optional, improves quality) Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

How It's Done

Worth paying attention to:

• 1. Fill a porous bag with 1–2 handfuls of finished compost per litre of water, or add loose compost directly.
• 2. Submerge in a bucket of water — rainwater or dechlorinated tap water is best.
• 3. Steep for 24–48 hours, stirring occasionally, or aerate with a pump for better results.
• 4. Strain out solids if not using a bag.
• 5. Dilute if concentrated, and apply directly to soil or as a light foliar spray.

Getting these details right matters more than it might seem — 1. Fill a porous bag with 1–2 handfuls of finished compost per litre of water, or add loose compost directly. 5. Dilute if concentrated, and apply directly to soil or as a light foliar spray. Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

Troubleshooting

Keep these points in mind:

• Smells bad/anaerobic — brewed too long or without enough airflow; use within 48 hours and aerate if possible.
• No visible benefit — compost tea is a supplement, not a substitute for good soil-building; use alongside, not instead of, regular compost.
• Clogged sprayer — strain thoroughly before using in a spray applicator.
• Over-application — more isn't better; stick to a light, regular feeding rhythm rather than heavy, infrequent doses.

Each of these compounds over a season — small misses early tend to show up later — smells bad/anaerobic — brewed too long or without enough airflow; use within 48 hours and aerate if possible. Over-application — more isn't better; stick to a light, regular feeding rhythm rather than heavy, infrequent doses. Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

Ongoing Timing

Best time. Throughout the growing season, timed with active growth phases.

Duration. Each batch brews in 24–48 hours and should be used fresh, within a day or two.

Maintenance. Brew a fresh batch every few weeks rather than trying to store it — it doesn't keep well.

Signs of success. A rich brown liquid with an earthy, not foul, smell.

It's worth reading these as a set rather than in isolation; they reinforce each other.

Tips & variations

A few notes worth having alongside the method above: Worm Farming (Vermicomposting), Hot Composting, Letting the brew sit too long and turn anaerobic, Expecting it to replace solid compost rather than supplement it. These come from the same printable card and are easy to miss on a first read.

Related Guides

A few related guides worth reading alongside this one:

• Building Healthy Soil
• Cold & Slow Composting
• Green Manures & Cover Crops
• Hot Composting

For the condensed printable version, head to the main guide page linked below. If something's already gone wrong, our Troubleshooting Directory indexes common problems by symptom across all 219 guides. As with every guide on this site, this is general information based on our own research and experience, not professional advice — your specific soil, climate, and circumstances will always vary from ours to some degree.

Our Crop Rotation Planner is a useful companion to this specific skill.

Frequently Asked Questions

→ View the printable A4 guide for compost tea