Dahlia Tuber Growing Guide

At Good One Flowers, we believe growing dahlias should be joyful and rewarding. With proper care, these stunning blooms will provide armloads of flowers from midsummer until frost. Whether you’re planting your first tuber or you’re a full-fledged dahlia addict, this guide will help you grow with confidence.

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Choosing the Right Location

Plant dahlias in full sun (at least 6–8 hours daily). The more sun they receive, the more blooms you’ll enjoy. Avoid low areas where water collects, as tubers can quickly rot in soggy soil.

Soil Preparation

Dahlias thrive in rich, well-draining soil. Amend with compost or well-rotted manure before planting. Loosen heavy clay soil and avoid adding sand alone, which can create compaction.

A simple soil test will help you understand exactly what your garden needs and prevent over-amending.

Planting Tubers

Wait until all danger of frost has passed and the soil has warmed before planting. In Michigan (Zone 6a), this is typically mid to late May.

Plant tubers 3–6 inches deep with the eye facing upward. Space plants 12–18 inches apart depending on variety.

If you want earlier blooms, you can pot them up 4–8 weeks before planting outside. It also helps satisfy that need to get your hands in the dirt sooner!

Watering

Do not water immediately after planting unless the soil is very dry. Once sprouts appear, begin regular watering.

Dahlias prefer deep watering rather than light, frequent watering. Consistent moisture throughout the growing season encourages strong plants and abundant blooms.

Many growers use soaker hoses or drip irrigation systems to ensure steady, deep watering.

Staking & Support

Install stakes or support at planting time to avoid damaging tubers later. Tall varieties benefit from sturdy staking or a corral system.

Most home gardeners use sturdy metal stakes. True dahlia addicts often prefer the corral method to support an entire row at once.

Pinching for More Blooms

When plants reach 8–12 inches tall, pinch the center growing tip. This encourages branching and results in more flowers per plant.

I know it’s hard to do, but it’s essential if you want lots of blooms!

Fertilizing

Use a balanced, low-nitrogen fertilizer once plants are established. Avoid high-nitrogen feeds that promote excess foliage instead of blooms.

Fertilize every three weeks for in-ground plants and every two weeks for container-grown dahlias.

Pest Management

Protect young plants from slugs and snails early in the season. Monitor regularly for pests and maintain good garden sanitation.

Sluggo is a reliable organic option for early-season protection. Stock up early — the slugs will!

End of Season Care

After the first frost blackens the foliage, cut stems back to 4–6 inches and carefully lift the tubers.

Allow them to dry before storing in a cool, frost-free location (ideally 40–50°F) for the winter.

A Final Note from Good One Flowers

Growing dahlias is part science, part patience, and part pure joy. Don’t be afraid to experiment, learn, and embrace the process. Before you know it, you may just find yourself becoming a dahlia addict too.

Happy growing! 

Stephanie