Everything you need to grow, tend, and fall in love with dahlias — from first planting to final tuber storage. Grown knowledge, straight from our fields.
Dahlias are planted as tubers in spring, once the soil has warmed and the threat of frost has passed. In most growing zones this means late April through May. Dahlias need warmth — a cold, wet spring is the fastest way to rot a tuber before it ever sprouts.
Choose a location with at least 6–8 hours of direct sunlight and well-draining soil. Dahlias do not like wet feet. If your soil is heavy clay, amend with compost or raise the bed.
Plant tubers 4–6 inches deep with the eye (growing point) facing upward. Deeper in sandy soil, shallower in heavy soil.
Space dinnerplate varieties 18–24 inches apart. Smaller varieties can be planted 12–15 inches apart. Crowding leads to poor airflow and disease.
Do not water immediately after planting. Wait until you see sprouts emerging (usually 3–5 weeks). Excess moisture before growth starts can rot the tuber.
Set stakes at planting time — pushing them in later risks spearing through the tuber. Use sturdy 4–5 ft stakes for tall varieties.
Watch for frost: If a late frost is forecasted after your dahlias have sprouted, cover them with row cover or a bucket overnight. A hard frost will kill young growth down to the soil.
When your dahlia reaches 12 inches tall with 3–4 sets of leaves, remove the central growing tip just above the second set of leaves. This one small cut redirects all of the plant's energy outward — instead of racing toward one bloom, it branches into multiple stems, each capable of producing its own flower.
On our farm, every single dahlia gets pinched without exception. The difference in stem count and season length is night and day. An unpinched plant might give you 8–10 stems all season. A pinched plant? Easily 30–40. More stems means more bouquets, longer harvests, and flowers that keep coming until frost.
A note from me: I know it feels terrifying to cut the head off of your babies. You've been watching them grow, you're so proud of that first little stem pushing up — and then someone tells you to just… snip it. I promise you, from the bottom of my heart, you will not regret it. The first time I pinched my dahlias I nearly cried. By August I had buckets overflowing. Trust the process.
At 12 inches tall with 3–4 leaf pairs. Earlier is better — waiting too long means less branching and a later start to the season.
Use clean snips or your fingernails. Remove the central tip just above the second set of leaves. One confident cut — don't hesitate.
Within 1–2 weeks, new shoots emerge from the leaf axils. Each becomes a productive stem. A single pinch can turn one stem into four or more.
More stems means more market bouquets, longer harvests into fall, and better flower quality. It's the single highest-return task of the whole season.
Dahlias are heavy feeders, but the wrong fertiliser at the wrong time will give you lush foliage and no flowers. The key is to match nutrients to growth phase — nitrogen early, phosphorus and potassium as blooms develop.
We start every season with a generous application of compost worked into the bed. Throughout the growing season, we feed every two weeks with a balanced low-nitrogen fertiliser once buds form.
A light balanced feed (5-5-5 or similar) when plants reach 12 inches. Avoid high nitrogen at this stage — it pushes leaves over flowers.
Switch to a low-nitrogen, high-phosphorus fertiliser (0-10-10 or similar). Phosphorus supports root development and bloom production.
Water deeply 2–3 times per week in hot weather. Let the top inch of soil dry slightly between waterings. Consistent moisture = consistent blooms.
A 2–3 inch layer of mulch around plants retains moisture, suppresses weeds, and keeps roots cool. Keep it a few inches away from the stem.
Avoid over-fertilising: Too much nitrogen late in the season will push soft, hollow stems that don't vase well. Less is often more once your plants are established and blooming.
Harvesting dahlias at the right stage makes an enormous difference in vase life. Cut too early and the bloom won't open. Cut too late and it will barely last a day. The sweet spot is when the bloom is fully open but the petals on the back still feel firm.
We harvest every morning before the heat sets in, plunging stems immediately into cool water and moving them to a cool, dark space for a minimum of 4 hours before arranging.
Harvest in the early morning or evening when temperatures are coolest. Midday harvesting dramatically reduces vase life.
Squeeze the stem just below the bloom. It should feel firm and resistant — not soft or hollow. If it's hollow, give it another day.
Cut stems as long as possible — back to a leaf node. Longer stems allow for recutting when arranging and give the bloom more water uptake.
Get cut stems into water within seconds of cutting. Some growers carry a bucket right to the plant. Dahlias wilt shockingly fast out of water.
Leave harvested dahlias in a bucket of cool water in a cool, dark place for at least 4 hours (overnight is ideal) before arranging.
Properly harvested and conditioned dahlias will last 6–10 days in the vase. Change the water every 1–2 days and recut stems at an angle.
In most climates, dahlia tubers must be dug before the first hard frost and stored over winter. In zones 8 and above, you may be able to leave them in the ground with a heavy mulch layer — but we always dig ours for inspection and division.
After a killing frost blackens the foliage, wait 1–2 weeks before digging (this cures the skin on the tubers). Then carefully lift the clump with a fork, working from the outside in.
After the first killing frost blackens the foliage. Wait 1–2 weeks to let the tuber skins cure, then dig before a hard ground freeze.
Use a garden fork and start 12 inches from the stem. Work around the clump, loosening the soil before lifting. Never pull by the stem — it snaps the neck.
Shake off excess soil. Do not wash tubers unless you plan to divide immediately — moisture promotes rot in storage.
Divide clumps so each tuber has at least one "eye" (growth point) near the neck. Use a sharp, clean knife. A tuber with no eye will not grow.
Store in a cool (40–50°F), dark, frost-free location. Nestle tubers in dry peat moss, vermiculite, or perlite in a box or bag. Check monthly for rot.
Label every variety before you forget. A permanent marker directly on the tuber or a tied tag is essential — they all look the same by spring.
Watch for rot in storage: Check tubers every 3–4 weeks. If you find soft or mouldy spots, cut them away with a clean knife and dust the cut surface with sulphur powder or cinnamon. Remove any fully rotted tubers immediately.
We're always happy to chat about growing dahlias — check our FAQ or reach out directly.