Repotting guide

When & how to repot Calendula 'Radio' (Calendula officinalis 'Radio')

Also called Radio pot marigold, quilled marigold.

More about calendula 'radio'

About Calendula 'Radio'

Calendula officinalis 'Radio' · also called Radio pot marigold, quilled marigold · flowering

Calendula 'Radio' is a striking pot marigold with fully double, quilled orange petals that radiate like spokes, giving a spiky cactus-flowered look. An easy hardy annual, it flowers fast from seed in full sun and cool conditions, attracting pollinators. The edible petals suit salads and cottage borders; deadheading keeps it blooming for months.

Mature size: 40-60 cm tall, 30-40 cm spread

How to tell calendula 'radio' needs repotting

Repotting on a calendar is less reliable than reading the plant. For calendula 'radio', watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot calendula 'radio'

Every 2–3 years, into bone-dry mix. Calendula 'Radio''s growth habit — bushy, fast-growing upright annual that branches freely and reflowers readily when deadheaded. — sets the pace. Calendula 'Radio' is a striking pot marigold with fully double, quilled orange petals that radiate like spokes, giving a spiky cactus-flowered look. An easy hardy annual, it flowers fast from seed in full sun and cool conditions, attracting pollinators. The edible petals suit salads and cottage borders; deadheading keeps it blooming for months.

What size pot to step calendula 'radio' up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Calendula 'Radio' stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot calendula 'radio'

Spring or summer, while calendula 'radio' is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting calendula 'radio'

Repot dry. Do not water calendula 'radio' for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty average, well-drained soil, ph 6.0-7.0 ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set calendula 'radio' at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep calendula 'radio' completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for calendula 'radio'

Calendula 'Radio' wants average, well-drained soil, ph 6.0-7.0. Undemanding; thrives in ordinary garden soil and even poor ground. Good drainage matters more than fertility, and overly rich soil favours leaf over flower. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting calendula 'radio' — frequently asked questions

How often should you repot calendula 'radio'?

Every 2–3 years, into bone-dry mix for calendula 'radio'. Repot calendula 'radio' every 2–3 years into a snug pot of average, well-drained soil, ph 6.0-7.0, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does calendula 'radio' need?

When is the best time of year to repot calendula 'radio'?

Should you water calendula 'radio' after repotting?

No — not straight away. Repot calendula 'radio' into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise calendula 'radio' after repotting?

Not immediately. Wait about 3 weeks after repotting calendula 'radio'. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.