Thalictrum, pigamon: planting, cultivation and association
Contents
How to plant, grow, and companion plant thalictrum in the garden
- Floriferous and spectacular, it is an imposing yet graceful perennial resembling a giant gypsophila
- Its opulent and airy flowering in pink, lilac, yellow, or white brightens shaded corners in spring and especially in summer
- It has beautiful lush foliage, finely cut in soft green or glaucous, similar to that of columbine
- Perfectly hardy and perennial, once well-rooted in rich, cool soil, it requires very little care
- Emblematic of soft gardens or English mixed-borders, it is our favourite perennial for natural scenes!
A word from our expert
Known as Pigamon or Columbine-leaved Pigamon, the Thalictrum is a floriferous perennial with delicate, finely dissected foliage in soft green or blue-grey, remarkable for the poetry and abundance of its flowering.
Its airy and ethereal inflorescences that reach heights of over two metres for some beautiful cultivars like Thalictrum delavayi ‘Splendide’ illuminate shaded areas of the garden. Resembling clouds of dishevelled stars, its tiny flowers create a mist of lilac, pink, white, or yellow from May to September, depending on the varieties. The Thalictrum delavayi, the most emblematic of the Pigamons, and the Thalictrum aquilegifolium, are two remarkably floriferous species.
Thalictrum delavayi Splendide: a variety that lives up to its name
Immense specimens like Thalictrum ‘Elin’ and ground-cover species like Thalictrum kiushianum, the Pigamon fits into all settings. The giants of the genus will play the dazzling role of a midground or background plant, creating an evanescent mist. The diminutive species will form lush flowering carpets for cool rockeries and walls.
Its tall, feathery silhouettes, highly prized in England, are great classics of blurred, natural gardens, adding a poetic and expressive touch to cottage gardens and mixed borders.
It is a must-have for rose gardens, providing nuances, lightness, and transparency. The Thalictrum is the ideal companion for old roses, with which it creates opulent and romantic spring and summer scenes.
Well established under the canopy of deciduous trees, in rich, cool but well-drained soil, and sheltered from the wind, the Pigamon forms generous clumps in just a few years alongside Japanese Anemones, Bleeding Hearts, Astilbes, Astrantias, Lilies, Foxgloves, or even hardy geraniums. It creates a happy contrast when associated with less flexible plants like Hostas or ferns.
Cut, its light flower stems make very pretty fresh or dried bouquets with a rustic spirit.
Romantic, airy, spectacular, discover the Thalictrum, this large, easy-to-grow floriferous perennial that brightens up the garden!
Botany
Botanical data
- Latin name Thalictrum
- Family Ranunculaceae
- Common name Pigamon, Delavay Pigamon, Columbine-leaved Pigamon
- Flowering May, June to July
- Height from 10 cm for dwarf species to over 2.50 m for the tallest
- Exposure partial shade, shade
- Soil type neutral to acidic (heather soil)
- Hardiness -15 °C
Thalictrum, also known as Pigamon, is a herbaceous perennial plant from the same family as buttercups: the Ranunculaceae. Native to cool, moist mountainous areas, it is most commonly found in temperate regions of the Northern Hemisphere, in America, Europe, and Asia, primarily in China and Japan. In the wild, it grows at altitude, in cool, shaded areas, by torrents, in forests, in meadows, and on grassy slopes.
Vigorous, Pigamon can be planted throughout France, except in very windy regions and Mediterranean climates. Most prefer regions with cool, humid summers. The apparent lightness and delicacy of Thalictrum is deceptive: it is a robust perennial with ironclad health. Perfectly hardy, Pigamon withstands frost and copes well with negative temperatures down to -15 °C, but only for a short duration.
In Greek, Thalictrum means “that greens quickly”, referring to its propensity to develop abundant foliage very quickly.
More than 130 species of rhizomatous or tuberous perennials make up this genus. From immense specimens to ground-cover species, every Thalictrum finds its place in the garden. The most emblematic of the Pigamons cultivated in our latitudes is the Thalictrum delavayi and Thalictrum aquilegifolium, two remarkably floriferous species. Some hybrids, like the Thalictrum ‘Elin’, are giants that can reach nearly 3 meters in height. Among the most commonly cultivated species, Thalictrum rochebrunianum is one of the most imposing. The Thalictrum actaeifolium and the Thalictrum flavum have the particularity of bearing fragrant flowers, not to mention the adorable ground covers like the Thalictrum kiushianum that does not exceed 10 cm.
Thalictrum aquilegifolium – Botanical plate
The large Thalictrum have an upright and airy habit, forming wide, vigorous clumps that can reach 60 cm in spread. They are perfect for planting in the middle or back of borders in semi-shaded areas, under trees, or in prairie gardens. The smaller ones make good plants for cool rockeries.
A bit slow to establish, Pigamon needs about two years to grow and then express its full potential. However, it is worth the wait because the longer it grows, the more beautiful it becomes. Once well-rooted, this rhizomatous perennial grows quickly to form dense clumps. Almost indestructible, it has a long lifespan.
In April, from its robust base emerge, slowly at first, very finely divided leaves and large, slender yet sturdy stems, more or less ribbed, very branched, blue-green or purplish-brown, almost black depending on the varieties.
Very quickly, as soon as the temperature warms up, it forms in just a few weeks a large, light, flowering mass made up of a cloud of small flowers.
Spectacular, the feathery flowering gives this large perennial the appearance of a giant gypsophila. From June to mid-September, flexible, very airy flower spikes can rise up to 2.50 m high for the Thalictrum ‘Elin’, bearing large panicles or loose corymbs, highly branched, containing countless fluffy balls that open into small star-shaped flowers (1 to 3 cm). Pink, yellow, lilac, pure white, or deep violet, they seem suspended in the air, like arachnid constellations, attached to their very fine peduncles. Lacking petals, each flower has simple or semi-double sepals that surround clusters of stamens that are sometimes so prominent that they give the flowers the appearance of fluffy pom-poms reminiscent of gypsophila or mimosa.
Thalictrum delavayi Hewitt’s double
The flowers are sometimes bicoloured with white or pink sepals and contrasting purple or lilac stamens with white tips, green-touched whites, or yellows. The sepals fall more or less quickly at the beginning of flowering, leaving the clouds of star-like stamens to provide the colour. Some cultivars, such as the Thalictrum delavayi ‘Hewitt’s Double’, do not have stamens but double flowers, resembling tiny soft, velvety roses.
The flowering lasts a good month. While Thalictrum delavayi blooms from summer until the end of autumn, the Thalictrum aquilegifolium offers a spring flowering, in May-June.
Fragrance is not the main asset of Thalictrum flowers; however, some species like Thalictrum flavum and Thalictrum actaeifolium are fragrant and exude a light bergamot scent. Particularly melliferous, they attract pollinating insects.
Each pollinated flower produces a small winged fruit. When planted in favourable conditions, in heavy, cool soil, Thalictrum (notably T. aquilegifolium) tends to naturalise by self-seeding spontaneously. As soon as they are mature, the brown seeds disperse, carried by the wind.
The cloud-like inflorescences of Pigamons make lovely airy bouquets both dry or fresh: in a vase, the flowers last a good week after being cut. They are perfect for rustic and romantic bouquets, combined with roses, lilies, or umbellifers.
A lovely foliage reminiscent of that of Columbines
The foliage, of rare elegance, is as interesting as the flowering. Deciduous, it disappears in winter and only reappears late in spring, allowing for the association of Thalictrum with bulbous plants that will occupy the space early in the season. Finely cut and light, it resembles that of certain ferns like capillary, but even more that of columbines: a resemblance that has earned Thalictrum aquilegifolium the nickname “Columbine-leaved Pigamon”. Very fine in appearance and delicate, the toothed leaves, divided into rounded and flat leaflets with 3 to 5 lobes, measure from 10 to 40 cm depending on the species. As they spread, they bring a certain opulence to the plant. The foliage takes on beautiful shades of green, from lime to glaucous with a slight bluish and silvery hue.
While it resembles Gypsophila paniculata, Thalictrum prefers the cool environments of woodland edges; it enjoys bright exposures but without direct sunlight during the hottest hours. Therefore, it should be given a spot exposed to morning or evening sun, under the canopy of deciduous trees. In contrast, Thalictrum does not like too dense shadows that would limit its flowering: do not place it in competition with shrubs that could deprive it of light and offer it too dry a soil in summer. It is better to give it a place sheltered from dry, strong winds that could dry out the foliage and flatten the tall flower spikes.
Very easy to cultivate and low-maintenance, it does require, however, to bloom well, a soil rich in organic matter, well-drained, and free of lime. While it tolerates a bit of all soil types (except for very poor, dry, and stony soils), its preference typically goes to woodland soil, neutral or acidic. It enjoys light soils, even heavy ones, but that remain cool and kept sufficiently moist with good mulch during the growing season. A cool soil allows it to develop vigorously.
Thalictrum aquilegifolium in woodland
The immense specimens like Thalictrum ‘Elin’ are rarely used in isolation but are planted at the back of borders, associated with other perennials with strong growth or with shrubs that will act as supports, preventing their clumps from flopping unattractively. Ground-cover species, such as Thalictrum kiushianum, are reserved for cool rockeries and flowering walls.
Thalictrum kiusianum and Pachysandra terminalis: a lovely combination for tree base
The specific name delavayi was given to Thalictrum in honour of Father Jean-Marie Delavay, a Christian missionary who, in the 19th century, collected one of the largest botanical collections in China for the National Museum of Natural History in Paris.
Main species and varieties
The genus Thalictrum comprises around 130 species with varying sizes and flower colours. From diminutive Thalictrum to giant Pigamons, each finds its place in the garden. Thalictrum delavayi is the most emblematic of the Pigamons, and along with Thalictrum aquilegifolium, it ranks among the most floriferous in the genus. Both feature numerous interesting cultivars. Among the most commonly cultivated species, Thalictrum rochebrunianum is one of the most impressive. While most Pigamons are unscented, some emit a light fragrance. The tall Thalictrum make excellent backgrounds or fillers for semi-shaded areas, while dwarf Pigamons like Thalictrum kiushianum are great for cool rockeries, slowly forming a charming, floriferous carpet.
Thalictrum delavayi - Meadow-rue
- Flowering time July to September
- Height at maturity 1,70 m
Thalictrum aquilegiifolium - Meadow-rue
- Flowering time July, August
- Height at maturity 1,20 m
Thalictrum flavum subsp. glaucum - Meadow-rue
- Flowering time July, August
- Height at maturity 1 m
Thalictrum kiusianum - Meadow-rue
- Flowering time May to October
- Height at maturity 15 cm
Giant Pigamons:
Thalictrum Elin - Meadow-rue
- Flowering time July, August
- Height at maturity 2,50 m
Thalictrum delavayi Splendide - Meadow-rue
- Flowering time July to November
- Height at maturity 1,75 m
Thalictrum delavayi Splendide Album - Meadow-rue
- Flowering time August, September
- Height at maturity 1,50 m
Thalictrum delavayi Hewitts double - Meadow-rue
- Flowering time July to October
- Height at maturity 1 m
Thalictrum rochebrunianum - Meadow-rue
- Flowering time August, September
- Height at maturity 1,50 m
Thalictrum aquilegifolium Album - Meadow-rue
- Flowering time July, August
- Height at maturity 1,20 m
Thalictrum Black Stockings - Meadow-rue
- Flowering time July, August
- Height at maturity 1 m
Thalictrum actaeifolium Perfume Star - Meadow-rue
- Flowering time July, August
- Height at maturity 80 cm
Thalictrum delavayi Album - Meadow-rue
- Flowering time August, September
- Height at maturity 1,50 m
Thalictrum delavayi Splendide - Meadow-rue
- Flowering time July to November
- Height at maturity 1,75 m
Thalictrum Elin - Meadow-rue
- Flowering time July, August
- Height at maturity 2,50 m
Thalictrum delavayi Splendide Album - Meadow-rue
- Flowering time August, September
- Height at maturity 1,50 m
Discover other Thalictrum - Meadow Rue
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Planting and maintenance
When to plant?
Thalictrum can be planted in spring from March to May after the frosts, or in autumn from September to November, after the heat of summer.
Where to plant?
Despite its appearance as a beautiful perennial that is very easy to grow, Thalictrum has a few requirements: it dislikes hot and drying exposures, dry and violent winds, and competition from roots.
Vigorous, Thalictrum grows almost everywhere in France, except in dry and very windy regions and in Mediterranean climates, as it fears scorching sun. The Pigamon will withstand summer heat in temperate regions, provided the soil remains consistently moist and cool.
With excellent hardiness, it withstands frost and can tolerate temperatures below -15 °C but only for a short duration.
Thalictrum thrives in a rather shady and well-cleared spot, sheltered from strong winds: it will flourish in partial shade, out of direct sunlight, under deciduous trees that provide a beneficial coolness. It prefers an open situation, which encourages it to reach its full height. Too dense shadows would limit its flowering: do not place it in competition with bushes that would deprive it of light. It also dislikes root competition: so be sure to give it some space!
It has a formidable enemy: the wind. A too windy location poses a threat to these tall perennials. These lofty, feathery silhouettes are graceful as long as they stand upright! They should be given a spot sheltered from dry and violent winds that could dry out the foliage and cause the clumps to flop.
While it integrates into all settings, it truly shines as a middle or background plant in borders. The tallest varieties (Thalictrum ‘Elin’, Thalictrum delavayi ‘Splendide’, Thalictrum rochebrudianum) should be planted at the back of borders, providing a vaporous relief and striking verticality. Planting them lower down will allow for full enjoyment of their flowering.
Ground-cover species like Thalictrum kiusianum, are perfect for shady rockeries and cool flower beds.
How to plant Thalictrum?
Thalictrum is slow to establish but once well established, after two years, it is very perennial. The secret to growing this vigorous perennial lies in the planting.
- The soil should be cool to moist, but well-drained (excess water in winter can be fatal), slightly acidic, and rich in organic matter. It does not like dry and poor soils where it will never be lush. It prefers rather heavy to light soils kept sufficiently moist with good mulch during the growing season.
- It tolerates slightly clayey soils but fears overly heavy soils. Do not hesitate to mix well-rotted compost into the soil, about 5 to 10 L, at the bottom of each hole before placing the root ball.
- Keep the soil cool at the base of the Thalictrum with mulch, especially during summer: this guarantees prolonged flowering.
- Once the young plants are established, they should not be disturbed. It is only in the second year that they will begin to thicken and flower properly.
- If you love the delicately cut and lush foliage of Thalictrum, so do gastropods! As the foliage disappears in winter, it is wise to mark the location of the plants with a small stake, to monitor snails and slugs in spring that devour the young shoots. Fern manure can help combat their attacks.
- Plant 2 to 5 plants per square metre, spaced at least 50 cm apart. Thalictrum dislikes root competition: avoid planting too close to bushes. It is a very airy plant that remains transparent; it is better to plant in numbers for a beautiful effect in a border.
- For giant pigamons, staking is sometimes essential, especially if they are planted in isolation. Keep this in mind: it will prevent the stems from breaking at the slightest gust of wind: a strong gust and your border will look like a battlefield after the storm! Another solution to prevent its flower spikes from collapsing in the middle of the border is to plant the Pigamon with other plants and shrubs, which it can lean on.
- A living mulch made of ground covers like Pachysandra, periwinkles, or bugle will keep the base cool.
- Water regularly the first summer to encourage rooting.
Maintenance
Once established in ideal growing conditions, Thalictrum is not demanding. Very resistant to diseases, it requires little care and proves to be a beautiful, trouble-free perennial with robust health! Provided the soil remains cool and sufficiently nourishing.
- Every winter, spread a good layer of fallen leaves; as it decomposes, this plant mulch will turn into humus.
- Fertilise each spring with compost to improve drainage in winter and facilitate root development.
- Stake large specimens that are very sensitive to wind if necessary.
- During dry and hot periods, mulch and water very regularly in the evening. It withstands summer heat, provided that watering is daily.
- Pruning is not necessary: simply remove faded flowers regularly to prolong flowering and prevent excessive self-seeding.
- At the end of autumn, cut back the deflowered stems by half.
- Avoid cutting the plant back to the ground in autumn: as its foliage does not reappear until spring, you risk forgetting it!
Possible diseases
Pigamons have only one known enemy: gastropods. Easy to care for, it does not suffer from diseases, except perhaps powdery mildew during dry spells. Watch for slug attacks at the start of the growing season!
Sowing
Dividing clumps is possible but tricky, as the risk of damaging the root is considerable. We do not recommend it, especially since Thalictrum is very easy to sow.
Indeed, sowing is the simplest method: this perennial is very easy to grow from seeds. While some varieties, such as Thalictrum delavayi ‘Hewitt’s Double’, which is sterile, as well as hybrids, do not propagate by sowing, most meadow rue produce seeds that germinate easily. Sowing should be done in autumn with fresh seeds from the year, harvested as soon as they turn brown, before they dry out, or with seeds sold in packets.
- Sow immediately under a cold frame in a mixture of potting soil and garden soil. This cold treatment will encourage germination.
- Plant the seeds 6 mm deep.
- Allow two to three months for germination; they will sprout in spring.
- Transplant when the seedlings have hardened off, when they reach 5 cm tall.
- Protect young plants from slugs at the time of planting.
Pairing Thalictrum
A reliable choice for light shade borders, Thalictrum is perfect for brightening up cool areas and playing with shades and gradients. With its tall, airy silhouette, delicate and light foliage, and pastel inflorescences, it transforms a simple perennial bed into a poetic mixed border. It is the ideal companion for old roses, with which it creates opulent and romantic spring and summer scenes. It embodies the charm of English cottages and blurred gardens with a pastoral or vicarage feel, bringing height, exuberance, and lightness. It is a must-have in rose gardens.
Thalictrum splendide White against a backdrop of roses: a true wonder for romantic gardens
It thrives in a community alongside robust perennials that will precede or take over its flowering, such as Japanese Anemones, Bleeding Hearts, Aconite, Columbines, Astrantias, Foxgloves, or even hardy geraniums.
Whether tall or ground-covering, Thalictrum fits into all settings, and can either play the dazzling role of a mid-height or background plant creating an ethereal mist or serve as a flowering mossy carpet for cool rockeries.
It creates a happy contrast when associated with less flexible plants like Hostas or ferns and works wonderfully with heather soil shrubs like Hydrangeas with which it composes lush beds.
You can also create a beautiful combination with Lilies, Astilbes or even grasses or Uvularia grandiflora. Thalictrum, flowering in late summer and early autumn, pairs beautifully with Asters that accompany its flowering. And to keep the base of the Thalictrum fresh, consider ground covers like Sweet Woodruff, a carpet of Periwinkles or Pink Bugle.
Another example of association: Thalictrum delavayi Splendide Album with Echinacea Catharina, Aster lateriflorus Chloe, Hosta Sagae, and Adiantum aleuticum Imbricatum
Need more inspiration? Discover our advice sheet: “Thalictrum, Pigamon: 8 beautiful pairing ideas”.
Useful resources
- Collect Meadow Rue seeds! This perennial is one of the easiest to sow!
- Planting perennials properly is easy with our advice sheet
- Which plants to associate with Thalictrum? Pierre, our horticultural engineer, shares his valuable insights.
- Also discover our advice sheet on slow-to-establish plants
Frequently asked questions
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Planted two years ago, my Pigamon is not growing, is that normal?
Yes, don't worry. The Pigamon needs about two years to settle in properly and reach its full potential. It will struggle in the first few years. However, it is worth the wait because, as the years go by, it becomes more beautiful. Once well-rooted, this rhizomatous perennial grows quickly to form dense clumps. Your patience will be rewarded: once established, it is virtually indestructible!
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Can Thalictrum be planted alone?
Yes, it is possible, but the effect will be less striking than for a planting in numbers. It is when associated with other perennials that its beauty is revealed. The immense specimens are rarely used alone but are preferably planted in the medium or at the back of a border, alongside other perennials with strong growth such as Hostas or Japanese Anemones, or even shrubs like Hydrangeas, which will play a supporting role, preventing their clumps from flopping over unsightly.
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I have a shady rockery, which Thalictrum should I choose to flower it?
The genus Thalictrum includes giant specimens as well as ground-cover species, which are somewhat less known but remarkably floriferous. Thalictrum kiushianum will be stunning in cool rockeries, shaded borders, and flowering walls. Year after year, it will form a charming little tapetum that is very floriferous, offering a profusion of small, soft pink-lilac pompom flowers from April to June, and again in September.
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My garden is quite exposed to the wind; can I try growing the Pigamon?
The Pigamon has a formidable enemy: the wind! An overly exposed situation poses a threat to these large perennials. Reserve a spot sheltered from the dry and violent winds that could dry out the foliage and cause the clumps to flop. Another precaution, especially for the giant varieties, is staking. This is essential, particularly if, like in your garden, they are exposed to the wind. Otherwise, the stems would break at the slightest gust, and your flowerbed would resemble a battlefield after a storm! To avoid this, we also recommend planting the Thalictrum alongside other perennial plants or bushes, which it can lean on.
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