Preslia cervina
Blue water spearmint, Hart's pennyroyal, Holt's pennyroyal
Also known as Mentha cervina
- Height × spread
- 0.4m × 1m
- Position
- Full sun
- Hardiness
- Colder than -20C (RHS H7)
- Flowers
- Summer
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
An aromatic plant that is valued for its herbal properties as much as for its use as a marginal plant for ponds or streams. It has stout upright stems that carry very long linear leaves that stretch out more or less horizontally. It flowers in midsummer when it produces clover-like heads of lilac flowers, the individual blooms whorled around the upright stems. They are loved by butterflies. It is happy in moist or boggy soil and can take water up to 10cm deep. It is best cut hard back once it has finished flowering. It will continue to spread if it is happy. The leaves are aromatic with the same minty fragrance as pennyroyal (Mentha pulegium), and can be used the same way.
- Flower colour
- Lilac, Purple, White
- Foliage colour
- Green
- Variegated
- No
- Scent
- No
- Shape
- Dome
- Height
- 0.4m
- Spread
- 1m
- Season of interest
- Spring, Summer, Autumn
- Flowers in
- Summer
- Evergreen
- Evergreen
- Garden style
- Water garden
- Sun or shade
- Likes full sun, tolerates part shade, tolerates light shade
- Soil type
- Chalk, Loam (normal)
- Soil pH
- All types
- Drainage
- Moisture retentive soil
- Hardiness
- Colder than -20C (RHS H7)
- Borders & containers
- Borders
- Water depth
- Up to 25cm
- Use for
- Deer resistant, Rabbit resistant, Butterfly attraction
- Hazards
- No
Spring
Spring · Outdoors
Feed with aquatic plant food
As the plant is grown in water, feed with an aquatic feed as directed on the packet. Do not exceed the amounts given as this can affect the water.
Spring-Autumn · Outdoors
Water frequently to keep the soil moist
The plant thrives in moist or boggy soil, doesn't tolerate dryness and should be watered frequently, not only after a period of drought, but if the soil begins to dry out spring to autumn. Check plants in pots more frequently, especially in hot weather.
Spring · Planting
Divide when too large
The plant can be divided in alternate years. Clumps may be divided into two or more pieces. Rhizomes can be cut whilst small bulbs or offsets are detached. The new plants can be grown in a container or planted in the ground.
Summer
Summer · Planting
Prune after flowering
When the plant has finished flowering, cut the trailing stems back by half their length or more to retain a compact and appealing habit.
Planting & general
Compost · Planting
Compost for aquatic plants
Use aquatic plant compost for pond plants (other composts contain nitrates that cause problems in ponds). Pond plants are generally planted in baskets and weighted to keep in position.