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.

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 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), as the latter often fail to grow

• Online suppliers sometimes offer bare-root plants and plug plants, which need potting up and growing on, 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

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

• Alstroemerias like rich soil, so dig in plenty of organic matter, such as garden compost or well-rotted manure, before planting

• Avoid planting taller types in a windy site, as the flower stems may get damaged

In containers

• Fill a large container with 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.

Watering

Alstroemerias are generally drought tolerant, but it is worth watering them in dry periods to encourage further flowering.

Plants in containers need regular watering throughout the growing season, as the compost will dry out quickly, especially in summer.

Feeding

To encourage bountiful and continued flowering, feed weekly with high potash fertiliser, such as tomato feed, throughout the growing season.

It is particularly beneficial to feed plants in containers, as they have less access to nutrients than plants growing in border soil.

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.

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, 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. 

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 is an ideal mulch, in a layer about 20cm (8in) deep.

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 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. 

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 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.

By seed

Alstroemerias can be tricky to grow from seed, and even with careful attention germination 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 in 8cm (3in) pots and cover the seeds with a thin layer of vermiculite. Cover the pots with cling film or a plastic bag to maintain humidity

• 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 – keep in clumps when potting on 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. 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.