Garlic Fertiliser Guide: How to Grow, Feed and Harvest Healthy Garlic Bulbs in Australia

Garlic is one of the most rewarding crops for Australian gardeners—easy to grow, space-efficient, and a staple in every kitchen. But to grow garlic successfully, you need more than just well-placed cloves—you need the right soil, timing, spacing, and feeding strategy. This guide covers everything you need to know about fertilising garlic, when to plant, how far apart to space cloves, and how to keep your garlic growing strong throughout the season.

How Does Garlic Grow?

Garlic (*Allium sativum*) is a bulb-forming plant in the onion family. Each clove you plant becomes its own full-sized bulb over time. Unlike fast-growing herbs or leafy greens, garlic has a slow, structured growth cycle—and it requires long, consistent feeding to reach full size.

Ideal Conditions:

Planting Time: In most of Australia, plant garlic from March to June (autumn) for harvest in spring or early summer. Cool climates can extend into July.
Sunlight: Full sun (6–8 hours daily). Avoid shady areas or overcrowded beds.
Soil: Loose, well-draining soil rich in organic matter. Slightly acidic to neutral pH (6.0–7.0).
Spacing: Plant cloves 5–8 cm deep, 10–15 cm apart in rows spaced 25–30 cm.

Can You Grow Garlic in Pots?

Yes—garlic grows very well in large, deep pots. Use a container at least 30 cm deep and wide enough to space 5–6 cloves. Ensure good drainage and water consistently, especially once shoots emerge.

What is the Best Fertiliser for Garlic?

Garlic is a **heavy feeder**, especially in the first few months after planting when it builds roots and leafy tops. Unlike fruiting plants, garlic needs a fertiliser that supports **leafy growth early** and **bulb swelling later**, with just enough nitrogen and a boost of potassium and trace elements.

Recommended Fertiliser Profile:

Moderate nitrogen (N): For steady leaf and stem growth without excessive soft foliage
High potassium (K): Improves bulb development and disease resistance
Sulphur, magnesium, calcium: Critical for flavour, clove formation, and structural strength

Complete Grow Recommended Products:

NPK 20-20-20 Liquid Fertiliser – Use during early growth. Delivers all-round nutrients to support top growth and early root structure.
NPK 4-18-38 + Cal-Mag – Switch to this from mid-season onwards. Encourages stronger bulb development and supports sulphur metabolism for garlic flavour.

Should You Soak Garlic Cloves in Liquid Fertiliser Before Planting?

Yes—**soaking garlic cloves in a mild liquid fertiliser solution for 2–12 hours** before planting can stimulate root growth and reduce fungal risk. For best results, use:

4 mL of NPK 20-20-20 per litre of water
Soak cloves for 6–12 hours, then plant immediately into moist, prepared soil

This is especially helpful in heavy soils or cooler regions where early root stimulation supports faster shoot emergence.

280518770_1054401255497842_8006648546826904018_n

When and How to Fertilise Garlic for Bigger, Better Bulbs

Garlic Fertilising Schedule:

At Planting: Soak cloves in NPK 20-20-20 before planting. Water in with the same diluted mix.
Weeks 2–8: Feed every 2 weeks with NPK 20-20-20 to support vegetative growth.
Weeks 9–16: Switch to NPK 4-18-38 + Cal-Mag every 3 weeks to support clove development.
Final 4 weeks: Cease feeding. Water as needed while bulbs finish maturing.

Additional Garlic Care Tips:

Watering: Water deeply once or twice a week—more during dry periods. Avoid overwatering late in the season.
Weeding: Keep garlic beds weed-free, as weeds compete for nutrients and moisture.
Mulching: Apply sugarcane mulch or straw around young shoots to retain moisture and reduce temperature swings.

Common Problems:

Yellowing Leaves: May indicate nutrient deficiency—use Cal-Mag or reapply NPK 20-20-20
Small bulbs: Usually caused by early nitrogen deficiency, poor drainage, or late planting
Splitting cloves: Caused by excess nitrogen late in the season—stop feeding 4 weeks before harvest

Harvesting Garlic:

Harvest when 3–4 bottom leaves have dried but the top is still green
Lift gently with a fork and cure in a dry, shaded spot for 2–3 weeks
Do not wash bulbs—brush off soil once cured

With the right fertiliser, spacing, and timing, you’ll produce large, flavour-packed garlic bulbs that store well and deliver rich flavour to your meals for months to come.