Wizard of Oz Dahlia

Wizard of Oz dahlia: overview

Wizard of Oz is a specialty decorative dahlia developed for the cut-flower market, featuring large, multi-petaled blooms on long, sturdy stems. It grows best in full sun with 6–8 hours of direct light daily, produces peak blooms from late July through fall frost, and performs across USDA zones 3–11 when given appropriate overwintering treatment.

Floret Flowers, the Washington State specialty cut-flower farm that pioneered many popular dahlia varieties available to US home gardeners, lists Wizard of Oz among their curated dahlia library. The variety reflects Floret’s emphasis on large, fully-petaled blooms with strong stem length—attributes that make a dahlia work both in the vase and in the garden.

Dahlias as a genus are native to Mexico and Central America. All US garden dahlias grow from tuberous roots—similar in form to sweet potato tubers—that are planted in spring and either dug for winter storage or left in ground in mild climates.

Planting Wizard of Oz dahlias

When to plant by zone

Soil temperature at 4 inches must exceed 60°F before planting. Cold soil delays tuber development and invites rot. Use a soil thermometer rather than relying on calendar dates—soil temperatures vary significantly by yard and microclimate.

Check last frost date by zip code to establish your spring planting window, and planting zones if you are unsure of your USDA zone.

Site selection

Sunlight: Dahlias need full sun—6 hours minimum, 8+ hours ideal. Less than 6 hours produces weak stems and reduced blooming. The Wizard of Oz variety, like most large decorative types, depends on strong light to produce the stem strength needed for cutting.

Soil: Well-draining, fertile soil with a pH of 6.5–7.0. Dahlias grown in waterlogged soil rot at the tuber. If your soil holds water, raise the planting area 6–8 inches or plant in raised beds. Add compost at 3–4 inches worked into the top 12 inches before planting.

Wind protection: Tall dahlias snap in wind. Plant near a fence or hedge that blocks prevailing winds, or stake at planting time.

Planting depth and spacing

Plant tubers horizontally, 4–6 inches deep, with the eye (the pointed bud on the crown) facing up. Set stakes or cages at planting time—driving stakes after the plant grows risks spearing the tuber. Space plants 18–24 inches apart in rows or 24 inches on center in blocks.

Water once at planting, then withhold supplemental water until you see shoots emerging—usually 2–3 weeks. Overwatering dormant tubers causes rot before shoots appear.

The pinching method for more blooms

Pinching is the single most impactful technique for dahlia production. When the central growing tip is removed, the plant redirects energy into lateral shoots—producing 3–4 branches where one would have grown. Each branch becomes a separate flowering stem.

Pinching instructions:

1. When the main stem reaches 12 inches tall and has 3–4 sets of leaves, locate the growing tip (the soft cluster of leaves at the very top).
2. Using your fingers or bypass pruners, remove the growing tip just above the top set of leaves.
3. The plant will produce 2–4 lateral branches from the leaf axils below the cut over the next 7–10 days.
4. Allow all lateral branches to develop and flower. Do not pinch again.

This technique is similar to what gardeners do with zinnias to encourage branching—see pinching zinnias for a visual walkthrough of the same approach applied to that species.

An unpinched dahlia produces 1–2 main stems. A pinched one produces 4–6 stems. Over the whole season, pinching typically doubles or triples total bloom count per plant.

Watering and fertilizing dahlias

Watering: Begin regular watering after shoots emerge. Once growing, dahlias need 1–2 inches of water per week in moderate weather, 2–3 inches during peak summer heat above 90°F. Water at soil level—avoid overhead watering, which promotes powdery mildew and botrytis on large-petaled varieties.

Fertilizing: Apply a low-nitrogen, high-phosphorus-and-potassium fertilizer once plants begin to bud. A formula of 5-10-10 or tomato fertilizer (similar NPK ratio) applied every 3–4 weeks from bud set through August promotes large blooms and firm stems. Avoid high-nitrogen fertilizers after bud set—excess nitrogen pushes leafy growth at the expense of flowers.

Bloom schedule and deadheading

Wizard of Oz dahlias, like most large decorative types, are mid-to-late-season bloomers—90–120 days from planting. Expect the first open flowers in late July to early August in zones 5–7.

Deadheading: Remove spent blooms promptly to encourage continuous flowering. For cut-flower production, cutting is preferable to deadheading—every stem you cut for a vase also removes a fading bloom from the plant. This promotes faster cycling of new flower buds.

Peak bloom in most US climates occurs in August through October, when dahlias benefit from cooling nights. They keep blooming until hard frost (28°F or colder). A light frost may damage blooms but rarely kills the plant.

Cutting and using Wizard of Oz dahlias

Dahlias are among the most rewarding cut flowers for the home garden. The large, fully-petaled blooms of the Wizard of Oz type create a focal point in any arrangement.

Cutting technique for maximum vase life:

1. Cut stems in the early morning when they are fully hydrated.
2. Choose blooms that are fully open—dahlia buds do not continue to open once cut.
3. Cut stems at 45 degrees, 12–18 inches long for arranging.
4. Immediately place the cut end in boiling water for 10 seconds. This seals the stem and prevents an air bubble from blocking water uptake—a technique called “conditioning.”
5. Move to a cool bucket of fresh water and allow to rest in a cool location for 2 hours before arranging.

Properly conditioned dahlias last 5–7 days in a vase. Without conditioning, vase life is typically 2–3 days. See attract pollinators to your garden for companion plantings that attract beneficial insects alongside dahlias.

End-of-season: digging and storing tubers

In zones 3–7, dahlia tubers must be dug and stored before the ground freezes. Wait until after the first light frost (26–30°F), which blackens the foliage—this signals the plant has moved sugars from the leaves into the tubers. Digging too early, before the plant has gone through light frost, results in less plump, less viable tubers.

Digging and storing steps:

1. Cut back the foliage to 4–6 inches above ground.
2. Insert a spading fork 12 inches away from the stem and lever up the tuber clump gently. Tubers are fragile—a broken neck where the tuber meets the stem means that tuber cannot sprout.
3. Shake off excess soil but do not wash the tubers.
4. Let tubers cure in a dry, sheltered area (garage, shed) for 5–7 days. This toughens the skin.
5. Pack cured tubers in slightly damp peat moss, vermiculite, or wood shavings in a cardboard box or plastic crate.
6. Store at 40–50°F with good air circulation. Temperatures below 35°F damage tubers; temperatures above 55°F promote sprouting in storage.
7. Check monthly through winter and discard any tubers that show soft spots or mold.

In zones 8–11, tubers may be left in the ground with a 4-inch mulch layer for frost protection. Plants in zone 8 sometimes need to be cut back and mulched heavily during rare hard frost events.

Dividing tubers for more plants

Each spring before planting, a dahlia clump dug the previous fall will have multiple tubers attached at the crown. Dividing the clump multiplies your planting stock at no cost.

Use a sharp, clean knife to separate individual tubers from the crown. Each division must have:

• At least one clearly visible eye (a small pink or white bud at the base of the neck, near the crown)
• A complete neck connecting the eye to the tuber body

Tubers without eyes cannot sprout. Eyes are easiest to identify after 2–4 weeks of warm storage in late winter, when they begin to swell and show pink or green color.

Common problems with dahlias

Powdery mildew: A white coating on leaves, common in late summer when nights cool but days remain warm. Improve air circulation by spacing plants 24 inches apart. Spray affected plants with a diluted baking soda solution (1 tablespoon per gallon of water) or a sulfur-based fungicide.

Slugs and earwigs: Both target dahlia foliage and flowers at night. Use a beer trap (shallow dish buried to soil level, filled with beer) or an iron phosphate-based bait around plants.

Stem rot: A rapid collapse at the base. Usually caused by planting in poorly drained soil or overwatering early in the season. Prevention through drainage improvement is the only reliable control.

Aphids: Check the underside of young leaves. A strong blast of water dislodges most colonies. Avoid systemic pesticides on dahlias grown for cut flowers or in pollinator gardens—dahlias are valuable foraging plants for bees.

Finding Wizard of Oz dahlia tubers

Wizard of Oz is a specialty variety available from Floret’s dahlia library online. Because specialty dahlia inventory is often limited, order in fall or early winter for spring delivery—popular varieties sell out by February at most suppliers. See Floret Flowers dahlia library for current availability and variety descriptions. For general dahlia care from a US university perspective, Iowa State University Extension dahlias guide covers the full cycle from planting through storage.

For more design ideas using dahlias alongside other summer bloomers, full sun flowers shows how dahlias integrate with annuals and perennials in beds and borders.