Planting Garlic and Onions in September: A Step-by-Step

September is the ideal moment to give your allium crops a fantastic head start. Garlic and onions planted now build strong roots before winter, thrive in cool soil, and produce bumper harvests next summer. Whether you’re a kitchen garden beginner or a veteran, this step-by-step guide will help you get it right—every year.

Why Plant Garlic and Onions in September?

• Early establishment: Roots begin to develop before cold stops growth, anchoring plants and boosting yields.
• Better bulbs: Autumn-planted sets tend to be larger, firmer, and less prone to disease.
• Beats the rush: Earlier planting means you’re ahead of spring’s mad dash and less likely to see seed stocks sell out.

Choosing the Right Garlic and Onion Varieties

Garlic:

• Softneck types: e.g., ‘Solent Wight’, ‘Early Purple Wight’ (well-suited to milder winters).
• Hardneck types: e.g., ‘Carcassonne Wight’, ‘Messidrome’ (better in colder areas, often with complex flavors).
• Buy from reputable suppliers—don’t use supermarket garlic (often not disease-free or adapted to your climate).

Onions:

• Autumn-planting sets: e.g., ‘Radar’ (yellow), ‘Electric’ (red), ‘Shakespeare’ (white).
• Check that you are buying sets labeled for autumn/winter planting—not all onions are suited to autumn sowing.

Step-by-Step Guide to Planting Garlic and Onions in September

1. Choose a Sunny, Well-Drained Spot

• Garlic and onions despise soggy ground—raised beds or ridges work well.
• Avoid recently manured soil; too rich encourages lush leaves but poor bulbs.

2. Prepare the Bed

• Remove weeds and rake to a fine tilth.
• Add well-rotted compost if soil is light or lacking in organic matter.
• Work in a general-purpose fertilizer if soil fertility is low.
• Lime the soil if it’s acidic (aim for pH 6.5–7).

3. Planting Garlic

• Carefully separate the bulb into individual cloves—leave the skins on.
• Plant cloves 2–3cm (1in) deep with the pointy end up.
• Space 10–15cm (4–6in) apart in rows 25–30cm (10–12in) apart.

4. Planting Onion Sets

• Push sets gently into the soil, tip just showing above the surface.
• Space onions 10cm (4in) apart in rows 20–30cm (8–12in) apart.
• Protect from birds who may pull young sets out—use netting or fleece.

5. Watering and Mulching

• Water newly planted sets in dry spells.
• Mulch with well-rotted compost or straw to keep weeds down and moisture steady, but don’t smother bulbs.

Caring for Your Crops Through Winter

• Keep weeds at bay—onions and garlic dislike competition.
• Remove any “bolters” (plants that form flower stalks early) in spring.
• Watch for rot or soft spots—improve drainage if you see these issues.
• In coldest regions, cover with cloches or fleece if frost is severe.

Spring to Summer: What Next?

• Side-dress with a little fertilizer when growth picks up in spring.
• Water as bulbs swell, but stop as harvest time nears to prevent rot.
• Garlic and onions are ready to harvest when tops yellow and flop (usually June/July).

Common Pitfalls to Avoid

• Over-watering or planting in soggy clay = small or rotten bulbs.
• Using supermarket bulbs—diseases and poor adaptation.
• Planting too early in a hot spell—wait until temperatures fall if September is scorching.

Conclusion

Giving garlic and onions a September start means trouble-free, low-maintenance crops and a kitchen rich with flavor next summer. With just a little preparation, you’ll enjoy some of the most rewarding harvests your plot has to offer.