The Living Soil Beneath Our Microgreens. Why A Healthy Biome Matters.

Publish Date: Friday, November 28, 2025  |  Time: 9:42 AM ET

Category: Basics / Education / Research

When folks look at a tray of bright, cheerful microgreens, they see the greens. What they don’t see is the living world under the surface — a whole underground community quietly doing its work so those tiny plants can stand tall, rich in flavor, and full of life.

Shirley and I talk about soil like it’s an old friend, because it is. To us, healthy soil is more than dirt. It’s a living ecosystem — a biome full of microscopic workers that help break down organic matter, hold water, exchange nutrients, and build a foundation for vibrant growth. Without that community of tiny helpers, plants stay pale, struggle to root, or simply refuse to thrive.

And that’s especially true for microgreens.

Microgreens grow fast and close to the soil surface. They don’t have months to adapt or “figure things out.” The soil has to be right from day one. It needs structure, good moisture flow, and — most importantly — a balanced population of microbes that keep everything steady instead of chaotic.

Today we’re digging deeper into soil microbiology, what makes a good compost-based mix, and where manure compost fits into all this — including what we’ve learned about Black Kow, a product many Florida gardeners swear by.

Why Soil Microbiology Matters for Microgreens

Microgreens live a short life, but in that time they go through explosive growth. Their roots need immediate access to:

• water that drains well without drowning,
• nutrients that aren’t too strong or overly concentrated,
• and a healthy, balanced microbial community.

Good compost contains a living network of beneficial microorganisms. These microbes help hold moisture without turning the tray into a swamp. They create a quiet “rhythm” in the soil — tiny exchanges of carbon, nitrogen, and minerals that guide young roots as they grow and anchor.

If your soil is too sterile, microgreens can grow, but the stems are often weaker and growth is less uniform. If the soil is biologically unbalanced — meaning the wrong microbes have taken over — molds and pathogens get first dibs.

Healthy compost is the sweet spot:

• alive but balanced,
• energetic but stable,
• full of beneficial microbes quietly doing their part.

Where Composted Manure Fits In

Not all composts are created equal. Some are plant-based, some manure-based, and some blends of the two. Manure-based compost, when it’s properly finished, plays a special role in soil health because it brings:

• deep biological activity,
• a stable structure,
• and micro-life that has already passed through a long heat-and-time breakdown.

The keyword here is finished compost.

A finished manure compost has gone through sustained high temperatures — often 130–160°F — long enough to:

• kill harmful bacteria (per USDA / NOP pathogen reduction guidelines),
• destroy weed seeds,
• break down organic matter into stable humus,
• and eliminate harsh odors.

When done right, you’re left with a mild, rich, earthy material that strengthens soil biology without being “hot” or risky.

This explains why many gardeners and growers turn to manure compost: it offers active biology in a stable form.

And naturally, that’s why Shirley and I wanted to understand whether Black Kow meets that standard.

Using Manure Compost for Microgreens (Our Perspective)

Microgreens are unique because they sit directly on the growing medium and are eaten raw. That means the bar for soil quality is much higher than it is for outdoor vegetables or ornamental beds.

For microgreens, any compost — manure-based or otherwise — must be:

• consistent in texture,
• free from large wood chunks,
• biologically stable,
• and produced cleanly with reliable testing.

A good microgreen medium drains evenly, encourages uniform germination, and stays steady from seeding to harvest.

We use a curated artisan soil mix that Shirley has perfected over time. It balances water retention with airflow, supports strong root growth, and remains biologically stable from start to finish. We’re proud of it because it does exactly what microgreens need — keeps the plants happy without stressing or smothering them.

But we still wanted to evaluate popular Florida composts that many gardeners trust, which led us to research Black Kow more deeply.

What We Found: Positive Takeaways About Black Kow Compost

We reviewed grower reports, university extension sources, and Black Kow’s own product statements. Here’s what stood out:

1. Their compost reaches appropriate high temperatures

Black Kow reports compost temperatures around 150°F, which falls within the ideal thermophilic range for pathogen reduction and organic matter breakdown.

2. They compost for months, not weeks

Their process reportedly takes around three months — a solid timeframe for thorough decomposition. Compost rushed through too quickly tends to have unstable biology.

3. They turn windrows regularly

Regular turning ensures even heating and prevents cold pockets, a cornerstone of safe manure composting.

4. The final product is mild and stable

Growers describe it as earthy, smooth, low-odor, gentle, and easy to mix — all signs of a finished compost.

5. It performs well for vegetables and seedlings

Gardeners consistently report improved soil structure, healthier plant starts, and fewer disease issues.

6. It contains no synthetic chemical additives

According to their documentation, nothing artificial is added during processing.

7. It’s trusted across Florida and the Southeast

Black Kow has been used by home growers and small farms for decades — longevity that usually reflects product reliability.

Final Thoughts from Wilshire’s Organics

We don’t promote products — we promote good soil, good practices, and good food.

Our honest take?

Black Kow appears to be a genuinely well-made manure compost. It’s stable, widely trusted, and built on the right foundations: heat, time, and turning. For garden beds, raised beds, vegetables, fruit trees, and overall soil improvement, it seems to be a dependable choice.

For microgreens, where the growing requirements are more sensitive, manure compost can still play a role — but only as part of a carefully curated mix that is clean, balanced, and biologically stable.

Healthy soil is a living thing. And well-made compost — manure-based or not — is one of the best gifts you can give your plants.

Thanks for growing with us.

References & Further Reading

• USDA National Organic Program (NOP) Compost and Pathogen Reduction Guidelines (thermophilic composting requirements: 131–170°F).
• EPA: “Process to Further Reduce Pathogens” recommendations for manure composting.
• University of Florida IFAS Extension — Soil biology & compost maturity indicators.
• University of Minnesota Extension — Best practices for composting manure safely.
• Black Kow Product Information & manufacturing overview (public statements).
• Soil Food Web School — overview of microbial activity in compost-based growing media.