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In this guide, we’ll walk you through the best way to pot up your dahlias for a strong, healthy start.

🌱 Starting Dahlias: Seed vs. Tuber

You can grow dahlias from seed (as shown with three-week-old seedlings), but planting tubers is the quicker route to full plants with lush flowers. When handling tubers:

• Choose ones that feel firm and show no signs of mould or rot.

• Look for small shoots already forming—this is a good sign of health.

🪴 The Right Pot and Compost

• Use an 8-inch (3-litre) pot with free-draining compost.

• Avoid rich garden compost—aquatic or seed compost works well to avoid rot.

• Plant the tuber with the shoot just level with or slightly below the soil surface.

• Position the thin roots downward and spread out the tuber before backfilling.

• Gently tap the pot to settle compost around the tuber and ensure good contact.

🌿 Feed and Label

Sprinkle a small amount of Root Well or similar mycorrhizal fungi and beneficial bacteria across the soil surface to promote healthy root growth. Don’t forget to label your dahlias, especially if you’re growing multiple varieties!

💧 Watering and Temperature

• Water lightly—moist but not soggy is key.

• Keep pots in a warm place (15–20°C / 60–70°F).

• If frost is forecast, bring them indoors or cover them—tubers are vulnerable to cold snaps.

🌼 Can You Plant Directly in Beds?

Yes—but only after the last frost, typically from mid-to-late May in the UK. Until then, starting in pots gives them a safer, more controlled environment to get established.

By potting up your dahlia tubers now and keeping them cozy, you’ll give them the best possible head start. Keep an eye out for growth, protect them from the cold, and get ready for a garden full of colour later in the year!