Top 5 Mistakes New Gardeners Make with Fertilisers

Feeding your plants seems simple—but it’s where most beginner growers go wrong. Here’s how to avoid common fertilising mistakes using CompleteGrow’s trusted products.

Whether you’re growing herbs on a balcony or veggies in raised beds, the right fertiliser makes a huge difference. But timing, strength, and product choice matter. Below are the top 5 fertiliser mistakes new gardeners make—and how to avoid them.

1. Using Too Much at Once

More is not better. Overfeeding can burn roots, yellow leaves, and damage growth—especially in containers or hydro setups.

How to avoid: Stick to the recommended rates on our labels. For example, our All-Purpose Liquid NPK 20-20-20 is highly concentrated—just a small amount diluted in water goes a long way.

2. Feeding Too Early

Seedlings don’t need fertiliser right away. Their energy comes from the seed itself. Fertilising too early can overwhelm tender roots.

How to avoid: Wait until plants have developed a few sets of true leaves. Then, introduce a gentle feed using a diluted dose of Indoor Plant Food Concentrate or our All-Purpose Liquid Fertiliser.

3. Using the Wrong Fertiliser for the Stage

Plants have different nutrient needs at each stage—what works for leafy growth won’t support flowering or fruiting.

How to avoid: Start with a balanced blend like NPK 20-20-20, then switch to our NPK 4-18-38 + Calcium & Magnesium when your plants begin flowering or fruiting. It’s especially effective for tomatoes and vegetables.

4. Forgetting to Feed in Containers

Soil in pots and planters loses nutrients quickly. Rain and watering flush them out faster than in-ground beds.

How to avoid: Feed every 1–2 weeks using a water-soluble option like All-Purpose Liquid Fertiliser. For indoor plants, apply Indoor Plant Food monthly to maintain steady growth.

5. Not Customising for Your Crop

Different crops have different needs. Leafy greens love nitrogen. Fruiting plants need potassium. Generic feeds often miss the mark.

How to avoid: Use our Custom NPK Powdered Blends service. We’ll formulate the right ratio for your crop type—whether it’s herbs, berries, greens, or a greenhouse mix.

Feed Smart from the Start

Fertiliser can make or break your growing season. When in doubt, start with less, follow a schedule, and use fertilisers designed for your garden style.

Need help choosing the right one?
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