Leucophyllum: Planting, Growing and Caring

Botany

The Leucophyllum genus comprises 19 species native to Mexico and the southwestern United States. They grow in desert areas, earning them the nickname “Desert Sage”. They are still very little known and rarely cultivated in France, despite being highly decorative with their silvery foliage and colourful flowers, in addition to being easy to grow.

Although nicknamed “Desert Sage” or “Rio Bravo Sage”, Leucophyllum is not a true sage (Salvia) and does not belong to the same botanical family (Lamiaceae). In fact, it is part of the figwort family, the Scrophulariaceae. These are mostly herbaceous plants, sometimes shrubby, with irregular flowers, usually tubular and bilabiate. This family includes buddleias, diascias, nemesias, verbascums…

The name Leucophyllum comes from the Greek leukos: white and phyllos: leaf, referring to its silvery foliage. The Leucophyllum langmaniae is nicknamed “Rio Bravo Sage”, referring to its geographical origin: the Rio Bravo, also called Rio Grande, is the river that marks the border between Texas and Mexico.

Surprisingly, Leucophyllum seems able to predict rain: it generally flowers just before rainfall, probably because it senses humidity in the air. In English, it is even nicknamed Barometer bush.

Leucophyllum forms a compact, dense and rounded bush, 1 m to 1.50 m tall with a spread of about 1 m at maturity. In the garden, it can be used for low hedges or in shrub borders, and it tolerates pruning very well.

It flowers in late summer or early autumn, and is then covered with countless small flowers, which appear in the axil of the leaves. They come in pink, mauve, purple or white shades, depending on the variety. The flowers have a tubular or funnel shape that opens into five lobes (corresponding to the five fused petals), arranged in two lips (two upper lobes close together, and three below). They measure 2 to 3 cm in all directions.

Generally, the flowers appear in successive waves, depending on rainfall. However, if summer is marked by a prolonged dry period, flowering will be single and brief, but more spectacular!

The flowers are melliferous, they are appreciated by pollinating insects that come to forage.

After flowering, Leucophyllum produces small capsules, dry fruits that open at ripeness to release the seeds they contain.

The flowering of Leucophyllum frutescens, Leucophyllum langmaniae and Leucophyllum laevigatum (photos: Forest and Kim Starr / Stan Shebs)

In addition to its flowering, Leucophyllum is appreciated for its very dense foliage with a beautiful silvery hue, very luminous. This colour is due to the countless small white hairs that cover the leaves. Living in desert regions, the silvery foliage of Leucophyllum is an adaptation to heat and drought: it reflects light rays and traps moisture in the small hairs covering the epidermis, which limits water loss.

The leaves have a rather ordinary shape, they are ovate to oblong, and measure about 2.5 cm long.

The Leucophyllum frutescens is evergreen, retaining its foliage all year round, even in winter.

In addition to being ornamental, its leaves can be consumed as an infusion. They are said to have hepatoprotective properties.

The silvery foliage of Leucophyllum frutescens (right photo: Forest and Kim Starr)

The main varieties of Leucophyllum

The Most Popular Varieties

Leucophyllum frutescens

This is the most widely cultivated species. It is a dense, rounded bush with stunning silvery evergreen foliage, bearing countless mauve-pink flowers from late summer to early autumn.

• Flowering time October, November
• Height at maturity 1,50 m

See the product sheet

Leucophyllum langmaniae

Also known as Rio Bravo Sage, this bush has a more compact habit than the previous species. From late summer onwards, it becomes covered in a multitude of lavender-coloured flowers.

• Flowering time September to November
• Height at maturity 90 cm

See the product sheet

Planting

Where to plant?

A plant of warm and dry climate, the Leucophyllum will thrive if placed in a sunny, south-facing spot. It is also important that the soil is very well-drained, sandy or stony, and preferably rather chalky. If your soil tends to retain water, do not hesitate to add some coarse sand or gravel, and plant it at the top of a slope, on a mound or bank, so that water drains away easily. The Leucophyllum can be planted in a rockery or atop a stone wall, and it is perfect for dry gardens without watering. Tolerant of salt and sea spray, it can easily be planted by the seaside. Finally, it is also suitable for creating a low hedge, alongside other bushes, or at the back of a flower bed, as long as the soil is well-drained. It can also be grown in a large pot with a well-draining substrate and placed on a terrace or balcony.

When to plant?

We recommend planting the Leucophyllum in spring, around April, unless you live in the south of France, in a warm and dry climate: in this case, it is preferable to plant it in autumn, so it benefits from milder temperatures to establish itself.

How to plant?

In the ground:

1. Dig a planting hole, at least twice the size of the root ball.
2. Optionally mix some coarse sand and gravel into the planting soil to improve drainage.
3. Plant the Leucophyllum, placing it right in the centre.
4. Fill in by replacing the substrate all around, then lightly firm the soil.
5. Water generously.
6. You can spread a layer of mineral mulch around the base.
7. Continue to water it regularly in the months following planting, until it is well established.

In a pot:

1. Choose a large pot with drainage holes.
2. Place a small layer of gravel, pot shards, or clay pebbles at the bottom.
3. Then add a well-draining substrate, such as a mix of compost, coarse sand, and garden soil.
4. Carefully remove the Leucophyllum from its original pot and place it in the new pot, centred.
5. Fill in by adding more substrate.
6. Lightly firm the soil.
7. All that remains is to water it.

Leucophyllum frutescens

Maintenance

We recommend watering the Leucophyllum during its first year of cultivation, until it is well established and develops its root system. Thereafter, water only during prolonged dry spells.

Naturally forming a dense, rounded habit, the Leucophyllum can easily go without pruning. However, if you wish to maintain a compact and regular shape, you may carry out light pruning in autumn, after flowering.

Once well established (after two to three years), the Leucophyllum can tolerate temperatures of around -10°C to -12°C, provided the soil is well-drained. In case of severe cold spells, especially in the first few years, temporarily cover it with winter fleece and remove it as soon as temperatures rise.

If growing the Leucophyllum in a pot, we advise occasional watering, as the substrate will dry out faster than in the ground. In winter, you can move the pot to a sheltered, bright but unheated location.

The Leucophyllum is rarely affected by diseases and parasitic pests.

Propagation

Propagation by cuttings

Leucophyllum can be easily propagated from herbaceous or semi-woody stem cuttings in summer.

1. Select and take a healthy stem cutting, about 10 cm long. Cut just below a node (the point where leaves attach to the stem).
2. Remove leaves from the lower part of the cutting, keeping only a few at the tip.
3. Prepare a pot by filling it with a light, well-draining growing medium, ideally a mix of compost and coarse sand, then water.
4. Dip the base of the cutting into plant hormone rooting powder.
5. Make a small hole in the growing medium using a thin stick or pencil, then insert the cutting.
6. Optionally place a plastic bottle over the pot to create a humid environment (closed-case propagation). Ensure occasional watering and prevent the cutting from touching the walls to avoid rotting.
7. Place the pot in a sheltered spot with bright, indirect light.

To learn more, feel free to consult our complete guide to propagation by cuttings

Association

Leucophyllum will integrate easily into a Mediterranean-style garden, especially as it tolerates salt and sea spray without issue, making it ideal for coastal planting. It pairs beautifully with other drought-tolerant plants such as lavender, euphorbia, rosemary, delosperma, and helianthemum. It particularly complements the flowering of Polygala myrtifolia, which shares its lovely mauve blooms. Also consider agapanthus, myrtle, Ceanothus ‘Autumnal Blue’, and Escallonia ‘Crimson Spire’… Finally, add a touch of exoticism with the finely cut foliage of a palm such as Chamaerops humilis ‘Cerifera’.

Polygala myrtifolia, Leucophyllum langmaniae, Chamaerops humilis ‘Cerifera’, Agave americana ‘Variegata’, Euphorbia myrsinites (photo: Guilhem Vellut), and Nerium oleander

Leucophyllum can also be simply incorporated into a dry garden or rockery, alongside sedum, houseleeks, opuntia, eryngium, and agave. Add lightness by interspersing clumps of ornamental grasses (Stipa tenuifolia, Pennisetum, Festuca glauca…). Also consider the colourful blooms of pinks, mullein, and catmint. You can also highlight Leucophyllum by pairing it with other silver foliage, such as Stachys byzantina, Salvia argentea, and Senecio cineraria.