When to plant Dahlias
Calendar windows
Dates shift with your latitude — they are calculated from your local last-spring-frost date, not from a fixed calendar.
At a glance
Killed by any frost — plant out only after the last one.
Practical notes
Tubers rot if planted into cold, wet ground, so wait until the frost risk has passed. Stake at planting time, not later — driving a stake in beside a grown plant spears the tuber.
Knowing when to pick
Cut flowers fully open — dahlias do not open further in the vase. The more you cut, the more it flowers; leave it uncut and it stops by August.
Storing the crop
Lift the tubers after the first frost blackens the foliage, dry them upside down, and store in dry compost at 5–10°C until spring.
Crop rotation
Quick and shallow-rooted — good gap-fillers between heavier crops.
Grows well with
Watch for
Full guide: dahlias diseases and pests (4) → with spread routes, compost verdicts and the prevention this list justifies.