How to grow alstroemerias

What are alstroemerias?

Alstroemerias are fleshy-rooted herbaceous perennials, which means they grow from bulb-like tubers, producing new leafy stems every spring, flowering in summer and autumn, then dying down over winter. They live for many years, and although they look very exotic they are generally hardy, so can be left in the ground over winter.

They originate from South America, hence their common name of Peruvian lilies. They have been widely bred to produce a stunning range of flower colours, with petals often dotted, blotched or streaked with additional hues.

The lily-like flowers are held in clusters at the top of leafy stems, which are produced in succession from early summer to late autumn. These can range in height from just 15cm (6in) up to 1m (3 ¼ft) or more.

Choosing the right alstroemerias

As long as you can provide a warm, sheltered, sunny spot in free-draining soil, alstroemerias should be happy in your garden. The flowers attract bees and other pollinating insects, so alstroemerias are perfect for a wildlife-friendly garden.

There is a wide range of cultivars to choose from, with flower colours that will match or contrast with your existing plants. They grow to various heights to suit all positions in borders and even containers:

• Flowers – the vibrant lily-like blooms come in shades of purple, pink, red, orange, yellow or white, often blotched, speckled or striped with additional colours. This diversity means there are choices to fit most colour schemes and styles of garden, from bold exotic plantings to romantic cottage-style borders. They mingle well with other perennials and will extend your flowering displays well into autumn
• Foliage – the leaves come in various colours too, from bronze, grey-green to variegated
  

  Variegated means having leaves or other plant parts with streaks, blotches or patches of different colours. Typically, these would be a combination of two colours, such as green and gold or green and white.

  cream and green
• Plant size – they generally grow to between 50cm (20in) and 1m (3¼ft) tall, but there are taller and shorter options too, to suit all positions in a border. The compact cultivars (from 15cm/6in tall) also work well in containers. Check plant labels for height and spread before buying

There are 15 alstroemerias with an RHS Award of Garden Merit, which shows they performed well in RHS trials, so are reliable choices.

To browse photos and descriptions of alstroemerias, go to RHS Find a Plant. You can search by flower colour, height, growing conditions, RHS Award of Garden Merit and more, to help narrow down your choices.

How and what to buy

• Alstroemerias are widely available in garden centres and nurseries, and from online suppliers by mail order
• They are mainly sold as small plants in spring or larger plants in flower in summer and autumn
• It is best to buy container-grown plants rather than dry tubers (similar to bulbs
  

  These are fleshy, rounded, underground storage organs, usually sold and planted while dormant. Examples include daffodils, tulips, hyacinths, lilies, onions and garlic. The term is often used to cover other underground storage organs, including corms, tubers and rhizomes.

  ), as the latter often fail to grow
• Online suppliers sometimes offer bare-root
  

  These have been lifted from the ground while dormant, with little or no soil around their roots. Various plants may be available bare root, including fruit trees, hedging plants and some perennials. They are generally cheaper than plants in containers, but are only available in winter/early spring, while dormant

  plants and plug plants
  

  Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

  , which need potting up and growing on
  

  Transferring young plants from one container to a slightly larger one, where they will have more room to grow and fresh potting compost. This encourages continuous, healthy growth.

  , before they can be planted outside. See our guide to buying plants by mail order

Use RHS Find a Plant to track down stockists of specific cultivars.

RHS guide to buying healthy plants

Where to plant

In borders

• Alstroemerias like a warm, sunny, sheltered spot. They will tolerate light shade, but flower best in sun. Avoid planting in a particularly cold or exposed location. See our guide to assessing your garden conditions
• They are happy in most soil types, as long as the soil is free draining and not prone to waterlogging – the roots may rot in damp conditions, especially in winter
• Avoid planting taller types in a windy site, as the flower stems may get damaged

In containers

• Fill a large container with peat-free John Innes No 2 compost, with added grit (20% by volume) to ensure good drainage
• Move the container to a frost-free location over winter

When to plant

• The best time to plant alstroemerias is in spring or autumn, when the soil is relatively warm and damp, so the roots establish quickly
• If you buy alstroemerias in flower in summer, plant them straight away and take care to water them regularly for the rest of the summer, to help them settle in

How to plant

Alstroemerias are quick and easy to plant in borders and containers. Simply follow our guides below.

Perennials: planting

Growing plants in containers

Watering

Alstroemerias are generally drought tolerant, so shouldn't need extra water once established.

Plants in containers need watering as needed throughout the growing season

The period of time when an individual plant is in active growth. This will depend on the local climate and light levels, and can vary between different plants, although it is broadly from spring to autumn.

, as the compost

Can refer to either home-made garden compost or seed/potting compost:

• Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

will dry out quickly, especially in summer.

Container maintenance

Feeding

It is beneficial to feed plants in containers, as they have less access to nutrients

To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth.

than plants growing in border soil. Feed with a high potassium fertiliser in summer, such as tomato feed

A potassium-rich liquid feed to encourage flowering and fruiting in various plants, not just tomatoes. Take care to follow the instructions on the packet.

, following the instructions recommended on the packaging.

How to feed plants

Supporting tall plants

It is best to support all but the compact alstroemerias, using either twiggy pea sticks or stakes. This will prevent the flower-laden stems breaking in windy weather or heavy rain.

Perennials: cutting back

Harvesting flowers

Alstroemerias make particularly long-lived cut flowers, staying fresh for a couple of weeks in a vase:

• To pick, grasp the stem gently, low down and pull upwards – a quick tug. This severs the stem below ground and stimulates another bud
  

  A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers.

  , so you get another flush of blooms. You can then trim your picked stem to the required length
• However, in the first summer after planting, flower stalks are best cut rather than pulled, until the plant is firmly rooted in

Deadheading

Once all the flowers in a cluster have faded, remove the whole stem with a gentle tug, the same as picking. This encourages further flower stems to sprout, keeps the plant looking good, and prevents it wasting energy on producing seeds at the expense of more flowers.

Deadheading plants

Overwintering

Plants in borders

Most alstroemerias are hardy and should survive the winter outdoors once their roots are well established and have grown deep into the ground.

However, for the first couple of years after planting, apply a thick layer of mulch in autumn to the soil around the plant, to help insulate the roots. Composted bark

Bark is the outermost layer of woody plants (trees, shrubs and woody climbers). It is several cells thick and provides protection against physical damage, disease and environmental stresses. Bark comes in a wide variety of colours and patterns, and these can help gardeners when identifying plants. The fissures and crevices of bark on older plants also creates valuable habitat for many garden creatures as well as lichens and small plants.

is an ideal mulch

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

, in a layer about 20cm (8in) deep.

Preventing winter damage

Plants in containers

• These should be moved to a frost-free location over winter, as the roots are more exposed to low temperatures than when growing in the ground
• This will also help to stop the compost getting saturated with excess winter rainfall, which can cause the roots to rot
• A sheltered porch or greenhouse would be ideal overwintering locations

Caring for older plants

Plants in containers should be re-potted every other year, into a container that is only slightly larger. See our guide to looking after plants in containers.

Established clumps in borders can be divided every few years to keep them vigorous and flowering strongly. See Propagating below.

Alstroemerias need little pruning. During the growing season

The period of time when an individual plant is in active growth. This will depend on the local climate and light levels, and can vary between different plants, although it is broadly from spring to autumn.

just remove the spent flower stems right at the base to encourage more to grow, then remove any remaining old stems in early spring before the new shoots appear.

Perennials: cutting back

The quickest and easiest way to make new plants is by dividing mature clumps. The resulting plants will be exactly the same as the parent plant.

Alstroemerias can be tricky to grow from seed, and if using collected seeds the resulting plants may differ from the parents. Plants grown from seed will take several years to reach flowering size.

By division

Established plants

Established plants have been in their current location for two or three years and so have well-developed root systems able to support strong growth with healthy foliage and flowers.

can be divided in April. However, the roots are fragile, so lift and divide plants with care, and replant the new divisions immediately. See our step-by-step guides below.

Perennials: dividing

By seed

Alstroemerias can be tricky to grow from seed, and even with careful attention germination

Germination is the process by which a seed develops into a new plant. It starts with the seed coat absorbing water, expanding and splitting, which allows oxygen and water into the seed so its food reserves can be broken down and used by the embryo for growth. The first root (called the radicle) pushes into the soil to anchor the new plant in place and start absorbing water and nutrients. The first shoot (called the plumule) then grows upwards, out of the soil, towards the light.

is not reliable.

However, it is easy to collect seeds from your own plants if you don’t deadhead them – just bear in mind that the resulting plants may differ from the parent. You can also buy packeted seeds, but the choice is limited.

• Seeds are best sown in autumn
• Pods can be collected from the plants as they turn brown and kept in a sealed paper bag until they explode. The seeds should then be sown immediately
• Sow in peat-free seed compost
  

  Seed compost is a free-draining compost formulated for germinating seed. It often contains a mix of fine materials including sterilised loam, coir, coarse sand or grit. It contains low levels of nutrients, as high levels could damage seedlings.

  in 8cm (3in) pots, covering the seed with a thin layer of compost
  

  Can refer to either home-made garden compost or seed/potting compost:

  
  • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

  . Keep the pots in a propagator
  

  A propagator is a portable, lightweight structure usually plastic, with a vented or unvented lid to provide a humid, slightly warmer atmosphere. It is useful to help seeds germinate and root cuttings. It may have adjustable, thermostatic temperature control.

  or cover with a glass pane to maintain humidity
  

  The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting.

• Keep indoors at 20ºC (68ºF) for three weeks
• Then place in a coldframe or cold greenhouse at 5ºC (40ºF) for three weeks
• After this, bring back indoors at 20ºC (68ºF)
• Germination can be erratic
• The roots are fragile, so don’t separate the seedlings
  

  A seedling is a young plant grown from seed.

  – keep in clumps when potting on
  

  Moving a plant from one pot into a slightly larger one, once its roots have filled the current pot. Most container plants need potting on every few years. If you leave a plant in the same pot for too long, its roots will become overcrowded (pot bound), hindering growth.

  and planting out

The resulting plants should flower in two or three years.

When grown in the right conditions, alstroemerias are generally trouble free. However, do look out for the following issues:

• Winter cold – especially when newly planted, alstroemerias may suffer in freezing temperatures. Until they have put down deep roots, it is best to protect them with a thick layer of mulch over the root zone in autumn
• Rotting – in damp conditions, the roots are prone to rotting, so grow in free-draining soil or compost
  

  Can refer to either home-made garden compost or seed/potting compost:

  
  • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

  . Bring container plants under cover over winter, so they don’t sit in cold, wet compost
• Viruses – may occasionally be a problem
• Slugs and snails – may attack the young shoots in spring

If you’re a member of the RHS, you can use our online Gardening Advice Service, via MyRHS, for any gardening queries.