When feeding plants in the ground, fertiliser on its own is not the answer.
Any nutrients you add to soil need help to become available to plants, and that help comes from organic matter and soil microbes.
Healthy soil is the key to healthy plants.
Think of feeding plants as a two-pronged approach:
- Improve the soil
- Then manage nutrients
Why Soil Health Comes First
Plants don’t absorb fertiliser directly from the soil in most cases. Nutrients need to be:
- Held in the soil
- Converted by microbes
- Released slowly in a form roots can absorb
Without organic matter and soil life, fertiliser is far less effective.
How Do I Know What My Soil Contains?
The simple answer is: you can’t tell by looking.
Different soils can look similar but behave very differently.
For a proper answer:
- A soil analysis can measure nutrient levels and pH
- Results should be compared with recommended levels for different crops
- Interpretation is best done by an expert
Step 1: Improve Your Soil with Organic Matter
What Is Organic Matter?
Organic matter comes from:
- Plants
- Animal waste
In other words, the contents of your green recycling bin.
Fresh organic matter should not be added directly to soil.
It must be composted and allowed to decompose first.
Why Organic Matter Is So Important
Organic matter does two vital jobs:
- Supplies nutrients (in small amounts)
- Improves how fertilisers work
Although organic matter contains lower nutrient levels than fertilisers, it does things fertilisers can’t:
- Improves soil structure
- Helps soil hold nutrients
- Reduces nutrient loss
- Stores moisture
- Regulates soil temperature
- Reduces erosion
- Feeds beneficial bacteria and fungi
Organic matter is the difference between good soil and poor soil.
Step 2: Choosing the Right Fertiliser
Once soil structure and biology are improved, fertiliser becomes far more effective.
What Kind of Fertiliser Should I Use?
It depends on what you’re growing:
- Trees, shrubs & perennials
- Permanent planting
- Use less fertiliser
- Organic or slow-release is best
- Fruit & vegetables
- Nutrients are removed at harvest
- Need higher levels of fertiliser to replace what’s taken out
Fast vs Slow Fertilisers
Fast Food Fertilisers
Think French fries and burgers:
- Chemically produced
- Quick results
- Nutrients available immediately
Problems:
- Soft, fast growth
- More attractive to pests and disease
- Nutrients used quickly
- Require frequent topping up
Best used sparingly and with care.
Slow Cooking Fertilisers
Think casseroles:
- Organic or mineral based
- Slow acting
- Need soil microbes to work
Benefits:
- Steady, stress-free growth
- Healthier plants
- Longer-lasting results
- Work best when combined with organic matter
These fertilisers reward patience and planning.
Top Tip
Start with the soil, not the fertiliser.
Improve soil with organic matter first, then feed plants according to what you grow. Healthy soil makes every fertiliser work better—and often means you need less of it.
