H1c - Tender, cool

Tender plants that enjoy summer outdoors but need cool, frost-free cover through winter because ordinary British frosts can seriously damage or kill them.

What it means

H1c plants need winter temperatures of 5 to 10 degrees C, so a cool conservatory, frost-free greenhouse or bright porch is suitable. They can spend the summer in borders, containers or sheltered patios, but should not be left outside through a British winter. Most lowland UK gardens experience colder conditions. The RHS rating indicates a plant's minimum cold tolerance, not the climate of a particular district.

Example plants

Common H1c choices include tomatoes, basil, busy lizzies, begonias and many other summer bedding plants. Dahlias are frequently grown as tender seasonal plants, although their tubers may be stored dormant and frost-free. Tender fuchsias, coleus and some ornamental peppers also belong in this broad growing approach. Always check the label, as hardiness can differ markedly between related plants.

Protecting these plants

Move H1c container plants inside before the first frost, ideally while they are still actively growing and undamaged. Keep them in bright, cool frost-free conditions and water sparingly during winter. Lift tender border plants where appropriate, remove loose soil and store dormant parts dry and frost-free. Replant or harden off gradually after cold nights have passed in late spring.

RHS hardiness ratings describe a plant's cold tolerance, not a geographic zone. Local conditions vary; the RHS or a local garden centre can advise. Page updated 18 Sep 2026.