<em>Tiarella</em> and <em>Heucherella</em>: planting and growing

Description and botany

Tiarella and Heucherella both belong to family Saxifragaceae. They are cousins of Heuchera, with which these two perennial plants hybridise easily. Heucherella is in fact the result of hybridization between Heuchera and Tiarella: X Heucherella is a hybrid genus created in 1912, combining best characteristic of both parents: decorative foliage and a dense, long flowering.

Genus Tiarella includes seven herbaceous, rootstock-bearing perennial plants with ornamental foliage native to cool understories and to banks of streams in North America and Asia. In gardens one mainly encounters Tiarella cordifolia, the heart-leaved tiarelle, which spreads by rootstock without ever becoming invasive, and Tiarella wherryi, without stolons and with slower growth.

About thirty varieties of Heucherella currently exist, not counting new cultivars that appear year after year.

Most tiarellas and heucherellas have a spreading habit. Some varieties (‘Tiarella Running Tiger‘) spread rapidly by leafy stolons that root like strawberry runners, producing new plants until forming large groundcover mats 10 to 90 cm high and equally wide at maturity.

Smallest varieties measure under 20 cm in leaf height, while larger cultivars reach at least 50 cm in height. Some, such as ‘Heucherella Redstone Falls‘, produce gracefully trailing stolons.

Tiarella wherryi or Wherry’s Tiarella is distinguished by an upright habit and forms clumps that are more spreading than tall, not exceeding 45 cm in height at maturity for a little more in width.

Tiarellas and their hybrids, the heucherellas, belong to those perennial plants notable for very decorative foliage with colours and textures incredibly varied. However, it is not always easy to tell these two plants apart because they are so close; differences depend on genus and cultivar.

Some Tiarella leaves: T. ‘Appalachian Trail’, T. polyphylla and T. cordifolia ‘Mint Chocolate’

From a thick stem emerge in spring rosettes of evergreen to semi-evergreen leaves depending on winter severity. Basal leaves are ovate, heart-shaped or rounded, about 5 to 15 cm long. They are simple or divided into 3 to 7 lobes of varying depth or palmate with a dentate margin and sometimes long petiolate, resembling maple leaves. Leaves of Heucherella, smaller but equally colourful as those of Heuchera, have same elegance as Tiarella leaves.

Very dissected, all display very vivid, warm tones, solid, variegated or marbled that shift gently with temperature, often more colourful in spring and autumn.

Silky or glossy, from tender green to emerald green sometimes shaded with red or bronze-purple, they show, depending on cultivar, a central maculation or strongly marked, contrasting veins, often purple on bright green lamina. Foliage often takes coppery autumn tones before turning to a deep red that spreads over almost entire lamina as cold sets in.

Some Heucherella leaves: H. ‘Copper Cascade’, H. ‘Solar Eclipse’, H. ‘Tapestry’, H. ‘Stoplight’

New hybrids offer remarkable colours ranging from chartreuse green to gold or silver, through apricot orange, coppery red, pink veined with purple or black-glazed purple. They develop into cinnamon, copper-orange, dusty pink or ruby tones by mid-summer. Strong venation often enhances leaf pattern beautifully.

In spring, fine pubescent scapes, sometimes reddish-brown, emerge from the tangle of small leaves. From April to August, sometimes into autumn for Heucherella depending on climate, star-shaped or bell-shaped small flowers 1 to 10 mm in diameter gathered in light panicles or in loose clusters, open up on stems sometimes reaching 50 cm above leaves, forming a frothy floral display. Stems are shorter on tiarellas.

This pretty cone-like frothy flowering is mainly springtime, February to June for Tiarellas, and summer to autumn for Heucherella. But both flower abundantly.

These small airy spikes in white, creamy white or pink later develop into shiny black capsule fruits.

They make excellent cut flowers for delicate fresh bouquets.

Easy to grow and with good hardiness beyond -15°C, Tiarella and Heucherella are excellent perennials for cool, shaded areas of the garden, providing a very airy aspect from spring to summer.

They thrive in all cool to moist, well-drained soils. These two perennial plants prefer shade to partial shade and dislike very hot exposures.

Tiarellas and Heucherella rank among best groundcover perennials: indispensable in a shady garden to dress roots of trees and shrubs, in borders, moist rock gardens or shaded edging, or even in pots or containers sheltered from strong sun.

Tiarellas are used in herbal medicine for their tonic and diuretic properties.

Main species and varieties

Most popular

Our favourites

Tiarella cordifolia

Spring flowering, perfect for covering large areas in fresh soil.

• Flowering time May to July
• Height at maturity 20 cm

See the product sheet

Heucherella Sweet Tea

A vigorous variety with remarkable apricot-orange leaves that take on a coppery-orange tinge in summer. Perfect in perennial beds and borders. Also a good groundcover. Can also be grown in a container on the terrace.

• Flowering time June, July
• Height at maturity 60 cm

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Heucherella Stoplight

Leaves yellow to tangy green, crinkled and marbled with brown-red. This excellent groundcover will also thrive in containers.

• Flowering time June, July
• Height at maturity 40 cm

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Tiarella Running Tiger

A new introduction with dark green leaves maculate with brown, spreading to form large tapetum groundcovers. Also cascades gracefully over a low wall or when hung in a basket.

• Flowering time May to August
• Height at maturity 30 cm

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Heucherella Golden Zebra

Sumptuous leaves that change colour with the seasons, topped by an airy, early flowering. Covers soil in perennial beds, borders or in containers.

• Flowering time June, July
• Height at maturity 40 cm

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Tiarella wherryi

A lovely perennial for cool shade that forms a low clump. A plant perfectly suited to ornament damp woodlands or cool rockeries.

• Flowering time June to August
• Height at maturity 30 cm

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Heucherella Brass Lantern

A recent introduction, highly ornamental and vigorous, in copper and amber tones, olive green in winter. Well suited to part-shade beds and colourful woodland settings.

• Flowering time July to September
• Height at maturity 35 cm

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Heucherella Redstone Falls

This is the first stoloniferous heucherella to have coppery-red leaves! Heucherellas of the 'Falls' series cascade. Ideal placed at the edge of a low wall or hung in a basket.

• Flowering time June, July
• Height at maturity 30 cm

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Tiarella Ninja

Long flowering and attractive dark evergreen leaves that will persist until autumn. Perfect for covering large areas.

• Flowering time May to July
• Height at maturity 30 cm

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Heucherella Copper Cascade

A festival of colours for this new variety! Highly appreciated in hanging baskets or containers.

• Flowering time July, August
• Height at maturity 30 cm

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Tiarella Sugar and Spice

An early flowering. Chic and graphic for spring compositions on a terrace, balcony or windowsill.

• Flowering time June, July
• Height at maturity 20 cm

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Heucherella Honey Rose

A remarkable recent introduction for shade and part-shade in beds or at the foot of trees.

• Flowering time July to September
• Height at maturity 35 cm

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Tiarella cordifolia Pink Brushes

Will brighten slightly shaded areas of the garden! This plant spreads by stolons and can quickly cover a large area.

• Flowering time June to August
• Height at maturity 30 cm

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Tiarella Sugar and Spice

An excellent, very floriferous and vigorous groundcover. Colours difficult areas such as shaded beds.

• Flowering time June, July
• Height at maturity 20 cm

See the product sheet

Heucherella Solar Power

Golden foliage marbled with brown like no other. Makes a good groundcover thanks to its tapetum habit.

• Flowering time June, July
• Height at maturity 35 cm

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Heucherella Citrus shock

An exclusive variety that forms a low, evergreen cushion of acid light-green leaves suffused with red. For cool, shaded areas of the garden, under trees.

• Flowering time July, August
• Height at maturity 35 cm

See the product sheet

Planting

Where to plant Tiarella and Heucherella?

Cold-hardy (sometimes to -20°C), and more tolerant of cold than of drought, Tiarellas and Heucherellas are better suited to cool temperate climate. For these plants that appreciate cool conditions, growing will be difficult in Mediterranean climate.

They need a soil rich and humus-bearing, remaining cool in summer but always well drained, especially during winter. In heavy soils that retain too much moisture their roots may rot; it is preferable to plant them on a raised mound or slope.

They thrive in partial shade, most of all avoiding hot, sunny exposures that can scorch their attractive foliage. They still need a few hours of sun each day to ensure good flowering.

Once well established, Heucherellas can however tolerate dry shade under canopy of trees and bushes.

Stoloniferous varieties will quickly occupy available space, being able to rapidly cover a large surface.

Clumps increase in size over time but remain always very easy to control.

They are also useful to limit weed proliferation and will advantageously replace short grass meadow in hard-to-access areas of garden. These perennial groundcover plants will save time weeding or will take over from somewhat sad spring bulbs after flowering.

These saxifragaceae are perfect to bring colour and brightness to cool shade, at edge of light wood. Their use depends on size of cultivars: small (10 to 15 cm tall), medium (20 to 45 cm) or giant (50 to 90 cm tall in flower). They show their full value in role of groundcover in understorey to dress shaded areas, slopes, as bank plants, to rapidly colonise bush massifs or crown a low wall even in winter.

Tapetum of Heucherella ‘Sunrise Falls’ with superb lemon-yellow foliage in spring then purplish in autumn!

They also compose window boxes, pots, bowls or hanging baskets in shade from which they will escape gracefully!

When to plant Tiarella and Heucherella?

Planting of Tiarellas and Heucherellas is done in autumn from September to November to promote rooting before winter or in spring in cold regions from March to April, outside periods of frost and drought.

How to plant Tiarellas and Heucherellas?

Easy to grow, they do well in ground or in containers.

In ground

These perennial plants with strong tapetum habit will flourish more in soil rich in humus. Add a good shovelful of well-rotted compost or manure at planting. In heavy soil, add coarse river sand to improve drainage.

Space plants about 30 to 40 cm apart and allow 6 to 9 buckets or plug plants per m2 to form a dense tapetum. Plant our plug plants if possible on receipt.

To colonise a neglected corner of garden, under trees or bushes for example, or to advantageously replace short grass meadow in lightly trafficked, shaded areas, you can also plant Tiarellas and Heucherellas en masse. You will be worry-free for many years!

• Dig a hole 3 to 5 times wider than the rootball
• Loosen soil well
• Place plant in centre of hole without burying collar too deeply, keeping it slightly below soil surface
• Cover rootball with mix of compost, garden soil and compost
• Firm down
• Optionally apply organic mulch
• Water copiously then regularly until established

In pot

• In container, spread a layer of clay balls to one quarter of height
• Plant Tiarella and Heucherella, collar level with substrate, in a well-drained potting mix for flowering plants (eg geranium compost)
• Keep rootball always slightly moist

Hanging basket of Heucherella ‘Redstone Falls’

More tips for planting our plug plants on our blog!

Maintenance, pruning and care

Tiarellas and heucherellas (x Heucherella) require very little care to stay attractive in all seasons. They have only a few essential needs.

They tolerate any well-drained soil, provided they are not short of water in summer.

In pots as in open ground, make sure to keep sufficient moisture at the base. The soil should always remain fairly cool throughout summer. Mulch the stumps in spring to keep the roots cool during summer. In regions with harsh winters, renew this vegetal mulch (flax chippings…) in autumn to protect them from severe frosts.

In pots, reduce watering in winter and do not let water stagnate in saucers. It can also be useful to mulch plants in pots.

If rainfall is scarce, water regularly during the first year after planting, then once or twice a week during hot spells or prolonged drought. Afterwards, these plants will become more tolerant of short periods of drought.

They prefer soil rich in humus. In poor soil, add each year at the start of spring a good layer of well-rotted compost, worked in lightly at the base of the plants.

Remove faded flower stems and wilted leaves as they appear.

At end of winter, around February–March, tidy the clump by removing leaves damaged by frost as new leaves begin to emerge.

If you want to limit spread, pull out excess stolons from stoloniferous varieties.

Divide clumps every 3–4 years in October or March to maintain vigour.

Repot every two or three years tiarellas and heucherellas grown in pots.

Possible diseases and pests

If heucherella has no enemies, its cousin tiarella can be more vulnerable to slugs and snails that love its young shoots in spring. Discover our natural solutions to keep these unwanted visitors away.

Potted specimens can be particularly sensitive to vine weevils, which devour roots and ‘notch’ the edges of leaves: destroy heavily infested young plants by burning and spray tansy decoctions as a preventive measure.

Likewise, it is relatively susceptible to powdery mildew during summer. For prevention: consult our page How to treat and prevent powdery mildew or white disease.

Abundant flowering of tiarellas

Multiplication

Heucherella and Tiarella are easily propagated by clump division or by separating rooted stolons in autumn or spring. Tiarella can reproduce by spontaneous sowing in the garden, which is not the case for Heucherella, which is sterile.

Clump division

Division helps to renew clumps when rhizomatous stems age.

• Using a garden fork, lever up part of the stump
• Divide it into several sections, each with a few roots and a leaf shoot
• Replant immediately in open ground or in a pot

Separating stolons

• Using a spade, cut away a rosette of leaves attached to the mother plant
• Dig up the stolon
• Replant immediately into moist soil so as to slightly bury the base of the seedling
• If carried out in autumn, pot up and overwinter in a frost-free place until spring

Using and combining them in the garden

Heucherellas and Tiarellas are indispensable in shade gardens, in pink or romantic gardens, in beds or woodland areas with their colourful foliage and soft pastel feathery inflorescences that brighten the smallest cool corner. With their graceful silhouette, they help lighten shade perennials that can be a little heavy or coarser foliage and provide a backdrop for more spectacular or taller flowers.

Excellent and very decorative groundcover in colourful woodland settings, under trees they combine easily with brunneras and lungworts and will be splendid in a family grouping with Heuchera.

An example of a woodland association: Geranium phaeum ‘Album’, Betula utilis var. jacquemontii, Tiarella cordifolia ‘Moorgrun’, Brunnera macrophylla ‘Jack Frost’ (or another silver-leaved variety), Saxifraga umbrosa and Astrantia ‘Star of Billion’ (or ‘White Giant’)

At the edge of a cool woodland, they are perfect with their shade companions such as ferns, ligularias, Cierges d’argent, Epimedium, shade hardy geraniums or filipendulas.

Classic partners for Tiarellas and Heucherellas, astilbes, alchemillas and hostas enjoy the same growing conditions and will make an impact in a bed with dappled shade.

Under trees, they are welcome among other ground-cover perennials for shade to create a carpet of subtle colours and textures with wood anemones, violets, creeping loosestrife, columbines, Asarum…

They form a classic fresh tableau with many spring bulbs such as snowdrops, hyacinths, daffodils, primroses and later tulips and colchicums.

An example of a border association: Galega orientalis, Lilium regale and Heucherella ‘Brass Lantern’

In a bed with romantic tones, they will grow between white or pink azaleas or cyclamens. At the front of a border, they combine nicely with columbines, bleeding hearts, pink geums and small violas.

Their foliage often turning reddish bronze in autumn harmonises well with a wide range of trees and bushes with late colouring such as maples, barberries and deciduous euonymus, smoke trees or grasses with autumn tints like Pennisetum setaceum ‘Rubrum’ and Miscanthus sinensis ‘Little Miss’.

In pots, new Heucherella hybrids make a striking display in mixed flowering containers alongside small airy grasses such as Carex and Stipa or with alyssums, campanulas, daffodils in spring and small cyclamens in winter.