A conspicuous flowering in spring as well as shapely foliage make the Indian rhubarb an attractive water plant all year round.
Profile of Indian rhubarb:
Scientific name: Darmera peltata
Plant family: saxifrage family (Saxifragaceae)
Other names: umbrella plant
Sowing time: spring
Planting time: spring and autumn
Flowering period: April to May
Location: sunny to partially shady
Soil quality: loamy to clayey, moderately nutritious, humus rich
These information are for temperate climate!
Use in: flowerbeds, borders, single planting, group planting, pond planting, flower garden, water garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 5 (-26 °C / -15 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of Indian rhubarb
Plant order, origin and occurrence of Indian rhubarb
The Indian rhubarb (Darmera peltata) is a perennial herbaceous plant native to Oregon and California in the western USA. In its natural habitat, the Indian rhubarb colonizes stream and river banks in mountainous regions. In Great Britain and Ireland, too, the perennial can be found in the wild, as it is naturalized there. It belongs to the saxifrage family (Saxifragaceae).
Characteristics of Indian rhubarb
The Indian rhubarb survives the winter underground, where it forms a strong dark brown rhizome. Its growth height is very variable, from 50 to 120 centimeters (20 to 48 in), and actually varies depending on location and climate.
Only after flowering the leaves of Darmera peltata sprout from the rhizome. Its leaf stem is located exactly in the middle of the leaf and the leaf blade has the round, shield-shaped appearance that gives the plant its name. The rounded leaf edge is lobed and because of its size of up to 60 centimeters (24 in) in diameter, the Indian rhubarb is considered a particularly beautiful leaf ornamental. A further attraction is the intensive leaf coloring in autumn. Starting from yellow to orange to a bright red-brown, the perennial then shows an attractive color change.
From April to May the up to 70 centimeter (28 in) high scapes of the Indian rhubarb shoot out of the earth. They are leafless, but glandularly hairy, about as thick as a finger and carry an umbel-like inflorescence at their end. The radially constructed single flowers have five white and pink petals.
After fertilization, follicle fruits form.
Indian rhubarb – cultivation and care
The Indian rhubarb likes to stand at permanently damp to wet places near the shore. It tolerates water depths of up to 5 centimeters (2 in) without problems. The optimal planting place is sunny to partially shady.
It is important that the soil is always moist; clayey, humus rich substrates are particularly suitable. In the garden, dry soil must be mixed with larger amounts of clay and peat. This basically increases the soil moisture and prevents the substrate from drying out too quickly in summer. A small amount of lime in the soil is tolerated and does not have a negative effect on the development of the plant. Due to its size, this unusual plant can only be cultivated in planters to a limited extent.
Planting Indian rhubarb
The best planting times for the Indian rhubarb are in spring and autumn. Keep at least 50 to 60 centimeters (20 to 24 in) planting distance between the individual plants, as the perennial is very vigorous in the right location. Ideal is a place in low water depth or in the constantly humid swamp zone.
Planting in a garden pond
A garden pond should blend harmoniously into the landscape. The Indian rhubarb is versatile and with its impressive growth height visually separates the shore area. An adequate and beautiful substitute for bamboo and reed. Darmera peltata can cope with a maximum water depth of up to 5 cm (2 in). However, the sales pot is not suitable for permanent pond planting.
A special plastic basket for water plants offers a better hold. The container inhibits the strong reproduction urge of the Indian rhubarb. Advantageous if you want to cultivate the plant specifically on the bank zone of the garden pond and do not want the ornamental plant to spread on its own.
- the plastic basket must be 2 to 3 cm (1 in) larger than the root ball
- Insert Indian rhubarb
- fill the spaces between with pond or plant soil
- insert into the pond zone and weigh down with pebbles
Expanded clay or pebbles in fish ponds effectively prevent the floating plants from washing the substrate out of the planters. Koi in particular are active in fine soils and dig up freshly planted plants during this activity.
Planting in bed
Only minimal effort is required to maintain Darmera peltata as a decorative backdrop in flower beds. The perennial herbaceous plant also shows to advantage in the swampy area of herb spirals.
Once the Indian rhubarb has grown, it can easily survive frosty temperatures. For this reason, the ideal planting time is between May and August. Enough time for the plant to prepare itself for the cold season.
- remove root remains and stones from the soil
- dig a planting hole
- loosen surrounding substrate sufficiently
- sprinkle compost into the planting hole
- enrich the excavated soil with clay if required
- insert ornamental plant up to the upper root neck
- fill substrate back and press firmly
- water vigorously
The plant, which originates from North America, likes moisture and wet feet do not harm it. In the garden pond the Indian rhubarb is planted in a water depth of about 5 cm (2 in). As a decorative border of ornamental beds and flower beds, the soil around the perennial needs regular watering.
On hot summer days it is recommended to check the moisture content of the substrate several times a day. If the root ball dries out completely, this inevitably means the death of the plant. A thick layer of bark mulch reduces the evaporation rate in the midday heat and keeps the moisture in the soil.
- water in the morning or afternoon
- shade the root region with low growing ground cover
- use stale water from the rain barrel
The Indian rhubarb is a light feeder, its need for nutrients is correspondingly low. The plant has no use for soils freshly prepared with manure. The roots are not able to deal with the high dose of minerals and “burn”. In the garden pond, the plant is fertilized by the nutrients and suspended matter dissolved in the water.
In the bed, an organic fertilizer, for example in the form of horn shavings or compost, is added. The material should be spread in spring and late summer and worked into the soil. Care should be taken not to damage the scale-like rhizomes growing just below the surface.
The leaves should be left on the plant until the winter. Only when they become unsightly and at the latest before the new budding of the flower in spring it is recommended to cut them back at the base.
If the Indian rhubarb spreads too much, you can pull its rhizome out of the ground in spring and share it with the spade.
The rhizome of the Indian rhubarb can be divided to obtain young plants. It is best to divide the perennial in the spring so that the freshly planted rhizomes can sprout again immediately. However, it is easier to grow by sowing. Darmera peltata needs light to germ, its seeds only need to be lightly covered with soil. Sowing is best done in spring.
Diseases and pests
If the water supply is insufficient, the leaves of the Indian rhubarb quickly become unsightly, otherwise the perennial proves to be insusceptible to plant diseases and pests for the water garden.
In autumn, Darmera peltata shows itself once again from its most beautiful side. The large, shield-shaped leaves first turn yellow, become orange and finally take on a bright red-brown coloration. Special precautions for the cold season are unnecessary and need not be taken.
Older plants can easily survive temperatures of -26 °C / -15 °F. In ornamental beds, it is recommended to cover the ground with a thick layer of brushwood or bark mulch. This warms the substrate and simultaneously supplies the soil with important nutrients and minerals.
Use in the garden
The Indian rhubarb is a leafy perennial that feels most at home in the constantly damp bank area at the edge of a pond or stream, because its water supply is secured here. Set individually or in small groups, it provides special eye-catchers all season long. As a companion, riparian perennials with less conspicuous foliage, but attractive flower decorations are ideal. Meadowsweet (Filipendula ulmaria), hemp agrimony (Eupatorium cannabinum) and purple loosestrife (Lythrum salicaria) are a good choice. You can also combine Darmera peltata as a border or in a bed with other ornamental perennials, but then regular watering is essential.
For those who do not have so much space available, the variety Darmera peltata ‘Nana’ offers a maximum growth height of 50 centimeters (20 in) and hence remains significantly lower than the actual species.