Gratiola officinalis - Hedge Hyssop, Pond Marginal Plant

Gratiola officinalis, known as hedge hyssop and sometimes sold as "summer snowflake", is a low plant with narrow, toothed leaves in opposite pairs. From June to August it carries small white flowers, often tinged or veined pink.

Hedge hyssop at a glance

Botanical name	Gratiola officinalis
Common name	Hedge hyssop, gratiole
Plant type	Low, clump-forming perennial; dies back in winter
Height and spread	About 25–40 cm tall, up to 50 cm wide
Flowers	White, often tinged or veined pink to purple-red, June to August
Position	Full sun or part shade
Soil	Boggy or wet soil, or very shallow water
Pond depth	0–5 cm of water over the crown
Hardiness	RHS H5 – hardy in a cold winter (-15 to -10°C)
Native to	Central and southern Europe (not UK native)

Where to plant hedge hyssop

The very shallow edge of a pond, 0–5 cm deep
Bog gardens and wet soil
Small ponds, where its low size suits

Is it poisonous?

Yes. All parts are poisonous. It was once used as a herbal purgative, and in excess it can cause kidney damage, bowel bleeding and miscarriage. Do not eat it or use it as a herb, keep it away from children and pets, and take particular care if you are pregnant.

How to plant and care for it

Plant in spring or summer in wet soil or very shallow water. It is generally free of pests and diseases.

Which size should I buy?

Bare-root plants (7 cm, 9 cm, 1 litre and 3 litre) arrive without a pot or compost and are the most economical way to plant a group. Potted plants (9 cm, 1 litre and 3 litre) arrive growing in our peat-free compost and give a faster display. Packs of 3 come in 7 cm, 9 cm, 1 litre and 3 litre bare-root sizes and cost less per plant. The 2x Pot & Compost option is two plants supplied with pots and compost.