Perennial Impatiens: Planting and Care

Description and Botany

The Impatiens or Impatiences or even perennial Balsams are herbaceous plants from the balsaminaceae family, much like our annual impatiens that adorn our terraces and balconies in planters or pots. The genus includes nearly 1000 botanical species, mostly tender perennials and annuals, along with numerous hybrids. They originate from New Guinea, Sri Lanka, Asia, Africa, and certain regions of the Himalayas. Most are frost-tender annuals and therefore generally prefer mild climates, but there are some perennial species with rhizomatous roots that offer good hardiness. Among these rare curiosities in cultivation, capable of surviving our moderately harsh winters, are the Impatiens omeiana or Mount Omei impatiens, a stunning ground cover, and the Impatiens tinctoria, a tall species from African tropical forests, hardy down to -12/-15°C with protective mulch.

Impatiens Noli tangere (botanical plate circa 1920)

The growth habit varies by species. The Impatiens omeiana forms a bushy clump 35-45 cm tall, with a spread of about 90 cm, while the Impatiens tinctoria can reach about 2, or even 3 m in height and 60 cm in width. Fast-growing, they form a bush with brittle, more or less branched and fleshy stems. The deciduous and abundant foliage emerges from the ground in spring and disappears in winter. It unfolds into lance-shaped leaves, pointed at the tip, with serrated edges. The Impatiens omeiana is remarkable for its lush, exotic-looking foliage. The leaf blade has prominent veins and is a glossy dark green, sometimes with bluish or silvery-white highlights in the case of the Impatiens omeiana ‘Ice Storm’.

The abundant flowering occurs from August to November. They generally bloom until the first frost. At the top of the flower stems, they bear clusters of 3 to 9 small orchid-like flowers. Suspended on a long, thin peduncle that makes them mobile, they are very elongated and tubular. The irregular corolla consists of 3 sepals, with the posterior one extended into a spur. They have a very distinctive appearance, quite different from the flat flowers of New Guinea impatiens. They emit a light gardenia-like fragrance and are white with a purple throat or yellow, depending on the cultivar. Those of the Impatiens tinctoria can measure up to 7 cm. Once pollinated, the flowers turn into small fruits, dehiscent capsules that burst open when touched at maturity, projecting their seeds a distance away. These balsam species go dormant in winter and re-emerge in spring.

The Impatiens tinctoria is traditionally used for its dye pigments. The Impatiens omeiana is an endangered species in its native habitat.

On the left, Impatiens tinctoria (©Scott Zona) and on the right, Impatiens omeiana and Cordyalis (© Peganum)

Main species and varieties

Impatiens omeiana Ice Storm

This cultivar stands out with its finely powdered silver foliage, as if frosted. Highly ornamental in cool and shaded areas.

• Periodo di fioritura October, November
• Altezza a maturità 45 cm

View product sheet

Impatiens tinctoria

A giant for autumn! It produces large, beautiful, stylised flowers in late summer and autumn.

• Periodo di fioritura October to December
• Altezza a maturità 2 m

View product sheet

Planting

Where to Plant?

More cold-resistant than their annual counterparts, perennial impatiens can withstand temperatures as low as -15°C, provided they have a good protective mulch. All impatiens require a cool, even moist, rich, and humus-rich soil: they are plants suited to cool woodland settings. They thrive in shade or partial shade and need soil that remains consistently moist to wet in spring and summer, but always well-drained, especially during winter. In cooler, rainier regions, they can tolerate light morning sun if the soil remains sufficiently moist. In soils that retain too much moisture or are clay-heavy, their rhizomes risk rotting. This perennial spreads via its rhizomatous rootstock: ensure enough space around the plant, as they dislike root competition. They are ideal under deciduous trees, in cool flower beds, rockeries, borders, or near water features. They are perfect for shaded urban gardens where sunlight is scarce. Impatiens can also be grown in outdoor containers or in dimly lit indoor spaces.

Impatiens tinctoria (© S. Rae)

When to Plant?

Perennial balsams are best planted in autumn, from October to November, to encourage root establishment before winter, or in spring, from March to May, avoiding frost and drought periods.

How to Plant?

In the ground:

These perennials will thrive in humus-rich soil. Add a generous shovel of well-rotted compost or manure at planting time. In heavy soil, incorporate river sand to improve drainage.

• Soak the root ball in a basin of water to rehydrate it
• Dig a hole 3 to 5 times wider than the root ball
• Loosen the soil and add a layer of coarse sand at the bottom for drainage
• Place the plant in the centre of the hole
• Fill with a mix of potting soil, garden soil, and compost
• Firm the soil
• Apply a layer of mulch
• Water thoroughly and regularly until established

In pots:

The substrate must be well-drained yet rich and moisture-retentive. Impatiens are sensitive to excess moisture, which can cause root rot.

• In a container with drainage holes, add a 3 cm layer of clay pebbles
• Plant in a mix of potting soil, optionally blended with garden soil
• Keep the root ball slightly moist at all times
• Adding mulch will help retain moisture in the substrate during summer

Care, Pruning and Maintenance of Perennial Impatiens

Perennial impatiens cannot tolerate drought but appreciate soil that remains moist, so we recommend regular watering in summer, whether they are planted in the ground or in pots. Reduce watering during their dormant period. Since they disappear in autumn and only reappear in spring, mark their location. In pots, water very regularly as soon as the soil begins to dry on the surface, but avoid overwatering to prevent any risk of rot. Do not leave water in the saucers.

A layer of organic mulch (linseed flakes, fern fronds, dead leaves, or straw…) around the clump will help keep the soil moist for longer and reduce the frequency of watering and weeding. Mulch the base in spring to keep the roots cool during summer.

In regions with harsh winters, renew this mulch in autumn to protect the plant from severe frosts. Remove the mulch in late March or early April, just before the growing season resumes. If you are concerned about very severe frosts in colder regions, you can dig up the tubers in autumn and store them in dry sand over winter.

In poor soil, add a good layer of well-rotted compost, crushed horn or dried blood by lightly working it into the soil around the base of the plants each year in early spring.

Remove faded flowers regularly to encourage impatiens to rebloom.

The giant Impatiens tinctoria can be pruned once a year in May-June, which will stimulate the growth of new stems and promote abundant late flowering.

Impatiens tinctoria (© Juniperus_scopulorum)

Diseases and potential pests

In case of excessive humidity, botrytis may affect flower buds. If you notice infestations of red spider mites (common in greenhouse-grown plants), spray the foliage to eliminate them.

Multiplication

Perennial impatiens can be propagated by division in spring or autumn. Choose a well-established plant that has been in place for several years.

• Using a garden fork, lift a portion of the clump by levering it out
• With a clean, sharp blade, take pieces of rhizome, each with a leaf bud
• Replant immediately in the ground or in a pot with moist soil
• Water generously

Propagation by softwood cuttings in June is also possible:

• Cut stems about 10 centimetres long
• Place them in a glass of water
• Once roots appear, transplant the cuttings into potting compost
• Move them to their final position when they are strong enough

Pair

Perennial Impatiens easily find their place in shade gardens, in borders or woodland settings. They brighten up even the coolest corners at a time when most other woodland flowers have faded. The Impatiens omeiana forms an excellent exotic-looking ground cover in woodland settings, under trees. You can pair it with other shade-loving ground cover perennials such as Heuchera, small ferns, and hostas, which thrive in similar growing conditions and create a stunning effect in dappled shade. Japanese anemones will accompany its flowering until the onset of winter, as will the Tricyrtis ‘Hirta’, also known as the Toad Lily, with its exotic and refined appearance.

Impatiens omeiana, Heuchera ‘Mint Marquess’, Hosta plantaginea, and Dryopteris Filix Mas fern

With its lush and generous foliage, Impatiens tinctoria has a distinctly exotic look that allows it to create a tropical-style garden when paired with other luxuriant foliage such as gunneras, majestic ferns, Rodgersia, and banana trees (Musa basjoo).

Impatiens tinctoria (© Scott Zona), Musa ‘Basjoo’, Rodgersia pinnata ‘Superba’, and Dryopteris ‘Wallichiana’ fern