Nutrient Lock-Up in Garden Soils

Why fertiliser doesn’t always work — and how to make existing nutrients usable again

What Is Nutrient Lock-Up?

Nutrient lock-up occurs when nutrients are present in the soil but plants can’t access them.

This is one of the most common — and frustrating — problems faced by New Zealand home gardeners. Everything appears to be done correctly:

  • Compost has been added

  • Fertiliser has been applied

  • Plants are watered and cared for

Yet growth remains weak or inconsistent.

The nutrients are there. The issue is access.

Common Signs Gardeners Notice

Nutrient lock-up often shows up as:

  • Yellowing leaves despite regular feeding

  • Poor flowering or fruiting

  • Slow or stunted growth

  • Plants that improve briefly after fertilising, then stall again

  • “Nothing seems to work, no matter what I add”

Because these symptoms look like nutrient deficiency, many gardeners respond by adding more fertiliser — which can actually worsen the underlying problem.

What Gardeners Commonly Try (And Why It Often Fails)

Most gardeners attempt to fix these symptoms by:

  • increasing fertiliser rates

  • changing fertiliser brands

  • feeding more frequently

While this can give short-term improvement, it doesn’t address the real issue: how nutrients move through the soil and into plant roots.

This is why many gardeners instead use soil-conditioning products designed to improve nutrient availability, helping plants make better use of what’s already present.

Why Nutrient Lock-Up Is So Common in NZ Gardens

New Zealand soils are naturally prone to nutrient lock-up due to both soil type and long-term garden management.

Volcanic and mineral-rich soils

Many NZ soils strongly bind nutrients, particularly phosphorus and trace elements.

Clay and compacted soils

Dense soils restrict root growth and nutrient movement.

Repeated fertiliser or lime use

Over time, nutrients can become imbalanced or shift into forms plants struggle to absorb.

High rainfall

Rainfall can disrupt soil chemistry and nutrient balance, especially in garden beds and lawns.

The result is a soil that contains nutrients — but doesn’t deliver them efficiently to plants.

A Smarter Way to Improve Plant Nutrition

Instead of continually adding more fertiliser, improving soil performance often delivers better results.

Products used for nutrient lock-up typically help by:

  • keeping nutrients in plant-available forms

  • improving nutrient movement in the root zone

  • supporting beneficial soil biology

  • helping roots absorb nutrients more efficiently

The improvement is usually steady and consistent, rather than a short-lived flush of growth.

Choosing the Right Option for Your Garden

Nutrient lock-up affects garden beds, vegetables, and lawns — but the best approach depends on where the problem is showing up.

All three options below are designed to improve nutrient availability in soil.
The difference is how much additional plant support is included.

🌱 Lazerhume — Soil-First Support

Best for:

  • garden beds

  • problem soils

  • long-term soil improvement

Lazerhume is often chosen by gardeners who want to focus purely on improving soil condition and nutrient availability, without adding extra nitrogen or iron.

Ideal for gardeners who already fertilise and want better results from what they’re using.

🥕 DCT Garden — Soil + Gentle Nutrition

Best for:

  • vegetables

  • flowers

  • fruit trees

  • general garden use

DCT Garden supports nutrient availability while also providing gentle nutrition and plant support. It’s commonly used where growth has stalled due to nutrient lock-up, particularly during active growing periods.

Well suited to gardens that need both access and support.

🌿 DCT Lawn — Soil Support for Lawns

Best for:

  • lawns with poor colour

  • lawns fed regularly but underperforming

  • compacted or high-use turf areas

DCT Lawn is designed for turf soils, supporting nutrient availability while helping lawns respond more evenly to feeding. It’s often used where lawns struggle despite regular fertiliser use.

Designed for the unique demands of lawn soils.

What You’ll See in Your Garden

When nutrient availability improves, gardeners will notice:

  • better leaf colour without increasing fertiliser rates

  • improved flowering and fruiting

  • more even plant growth

  • reduced need for constant feeding

This approach works alongside existing fertiliser programmes rather than replacing them.

When Nutrient Lock-Up Is Most Likely

Nutrient lock-up is common in:

  • long-established gardens

  • raised beds with mixed or unknown compost

  • clay or mineral-rich soils

  • high-rainfall regions

  • lawns and gardens that decline despite regular care

If your garden has been fed consistently but performance keeps dropping, nutrient lock-up is often part of the picture.

A More Balanced Way to Feed Your Garden

Instead of asking “What else can I add?”, it can help to ask:

  • Are nutrients actually available?

  • Can roots access them?

  • Is the soil supporting plant uptake?

When soil function improves, plants are better able to use what’s already there.

Still Unsure Which Option to Choose?

If nutrient lock-up is the issue, improving nutrient availability is the first step — regardless of whether you’re treating garden beds, vegetables, or lawns.

Explore the option that best matches where the problem is showing up in your garden.

Similar Problems Gardeners Often See