Yucca

Overview

Official Plant Name	Yucca (various sub-species)
Common Name(s)	Adam’s Needle and Thread, Spanish Dagger
Plant Type	Shrub / Tree / Perennial / Houseplant
Native Area	Americas & Caribbean
Hardiness Rating	Varies – some tender, some hardy
Toxicity	None
Foliage	Evergreen, spiky leaves
Flowers	Some have cream-white flowers
When To Plant (Outdoors)	April, May, June, September, October
Flowering Months	July, August

Yuccas are interesting, architectural plants which are grown as houseplants or outdoors in UK gardens.

There are a number of different yucca types that can be interesting plant choices for UK gardeners.

Tender yuccas can be grown as houseplants, in greenhouses or conservatories – while there are also hardier yuccas which can be grown outdoors in summer; some even year-round outdoors in the right locations.

What is Yucca?

Yucca is a genus of perennial shrubs and trees in the Asparagaceae family, and the Agavoideae subfamily.

There are around 40-50 species within this genus, which are notable for their tough, evergreen, sword-like foliage and tall flower panicles of bell-shaped blooms.

Yuccas are incredibly adaptable as a genus, and species have evolved to cope with a wide range of climates and ecological conditions.

They can be found in varied habitats, from deserts and badlands, to prairies and grassland, to mountainous regions and coastal sands throughout a range of semi-arid environments in subtropical and semi-temperate zones.

Why Grow Yucca?

Yucca is a popular plant for ornamental use in gardens (or as houseplants) because it has such a strong architectural form.

Hardier types can add a dramatic accent to a suitable garden, while houseplants can be a great addition within interior décor.

When in flower, yucca can be attractive to pollinators in a garden. And in warmer, milder regions, some varieties form fruits which are popular with garden birds.

Types of Yucca to Grow

Some hardy yucca varieties which can sometimes be grown outdoors in the UK include:

Yucca filamentosa

This is a small stemless shrub which forms clumps of deep green leaves which are edges with curled filaments.

The clumps grow to around 75cm height, with a spread of around 1.5m. In late summer, flowers are borne on panicles that can reach up to 2m in height.

This is a good choice for dry, hot borders and courtyard gardens. The hardiness rating of this yucca is H5.

Yucca flaccida

Yucca flaccida such as ‘Ivory’ or ‘Golden Sword’ (both of which have received an RHS AGM) are also good choices for courtyard gardens or other sunny, relatively dry spots in the ground or in containers.

The former has white flowers on panicles around 1.5m high, while the latter has lance-like leaves with golden stripes down their centres, and creamy white flowers on panicles around 1.5m high.

Both form clumps of leaves around 55cm high and up to 1.5m wide.

This variety is also rated H5 hardy.

Yucca gloriosa

Also known as Spanish dagger, this is also a hardy yucca suitable for borders or courtyard garden cultivation.

It is a larger single-stemmed shrub that can reach 2m in height and width.

From late summer to autumn, flowers are born on panicles 2.5m high. The flowers are creamish, sometimes with a purplish tint.

There is also a variegated version ‘Variegata’ with leaves striped and edged with creamish-yellow hues. Again, this is H5 hardy.

And more tender Yucca grown in the UK include:

Yucca aloifolia

This tender yucca can grow to 8m in height and 4-5m in width, though is usually kept smaller and grown in containers in the UK.

It is great for a cool conservatory, or as a houseplant – surviving temperatures down to a minimum of around 7°C. The hardiness rating is H3.

It has sharp, pointy leaves, and forms white or purple-tinged flowers.

Yucca elephantipes

Another large tender yucca, this plant can grow to around 10m in height, and can spread to 5-8m.

Smaller examples are often grown indoors, in containers – sometimes to be taken outdoors during the summer months – though this plant can only cope with temperatures down to around 10°C.

It has a hardiness rating of H2.

Where to Grow Yucca

Hardier yucca (such as the first three options mentioned above) are H5 hardy and can be grown in full sun in a south or east-facing spot, in well-drained chalk, loam or sandy soil.

The plants can grow in locations which are sheltered or exposed, but will appreciate being placed in as hot and sunny a spot as possible.

Tender yucca, though they can be placed outside in a warm and sunny spot in summer, are usually grown as houseplants, or in a cool conservatory.

Outdoors, yucca can work well in architectural planting alongside other spiky and architectural plants, to give a warm, sunny garden in the UK an exotic feel.

Yucca also work well as climate-change conscious planting in arid conditions, in dry climate planting known as xeriscaping schemes for more (or increasingly) drought-prone areas.

Planting Yucca

When choosing a yucca to plant, one of your first and most important decisions will be whether you would like to opt for a tender or a hardy yucca.

You will need to decide whether you will grow outdoors in a suitable spot, or will be growing under cover in a container.

If you are planting outdoors, make sure that you choose a spot with as much sun as possible, and where necessary, amend the soil to improve drainage before you place your new plant.

Dig your planting hole big enough to accommodate the root system, with stones, gravel or grit for drainage at the base. Make sure the plant is rested at the same level in the soil that it was in its pot and that water can drain away freely.

If you are growing in a container, make sure that this is of sufficient size to accommodate the plant you have purchased. And make sure the container allows water to drain freely from the base.

Fill your container with John Innes No. 2 compost (or equivalent) with 20-30% added grit by volume to improve drainage.

Hardy yuccas outdoors should usually be planted between May and September. Yuccas to be grown as houseplants can be planted up into new containers at any time of year.

Plant Care Guidelines

Caring for Hardy Yucca Growing Outdoors

Hardy yucca grown outdoors can be moderately low-maintenance plants, which, when placed in the right spot, will require little ongoing care.

Water freely during dry periods in summer, but curtail watering in autumn and cease over the winter months.

While you may feed with an organic liquid plant feed over the summer months, this is not usually required when yucca are grown in moderately fertile soil.

Mulching around perennial plants in your garden each spring with organic matter can help retain moisture in a dry and sunny spot, and maintain fertility over time.

Pruning is not usually required on most yucca. However, to keep things looking neat you may remove damaged leaves and spent flower spikes from your yucca in the spring.

This is also true for young or tender yucca grown in containers/indoors.

Caring for Tender Yucca as Houseplants

Tender yucca are suitable for indoors cultivation, though pots may also be placed outdoors during the summer months.

Water yucca freely over the summer months, remembering that plants grown in containers will typically require more water and dry out more easily than those grown in the ground.

However, from the end of September, you should water yucca only sparingly. Water well, but only when the top 5cm of the potting mix has dried out.

It is also a good idea to feed container-grown yucca with a balanced, organic liquid plant feed once a fortnight over the growing season, from April to September when growing in containers.

If you have placed a container-grown yucca outside over the summer, make sure you move it indoors before temperatures fall below around 7-10°C at night.

Move them indoors or into a cool conservatory where the minimum temperatures can be maintained.