How to grow and care for Mirabilis jalapa
Advice on growing and caring for Mirabilis jalapa, the four o'clock plant.
Mirabilis jalapa is a night-scented plant that blooms over a long period in summer. Ideal for growing in pots and borders, it bears trumpet-shaped flowers in a range of colours including pink, red, yellow, and white, on small bushy plants. These open in late afternoon or early evening, which gives it one of its common names, ‘four o’clock plant’. Another popular name is marvel of Peru, due to its Central and South American origins. Widely naturalised worldwide in frost-free countries, Mirabilis jalapa can be invasive, but in the UK there are no such issues as it only survives winter in the mildest areas.
How to grow Mirabilis jalapa
Grow Mirabilis jalapa from seed or buy dormant tubers, from late winter to mid spring. Plant out after the last frosts, in a sunny, sheltered site. Water regularly and feed monthly. In most of the UK, Mirabilis jalapa is borderline hardy and best treated as an annual, discarded when flowering finishes. Alternatively, lift the tuberous roots in autumn and store frost-free to replant the following spring.
Where to grow Mirabilis jalapa
The sweet evening scent and long flowering period of Mirabilis jalapa makes it ideal for patio pots or beds. Site in full sun and fertile soil that drains freely. Mirabilis jalapa grows to around 45-90 cm tall. Best planted in groups or clumps of three to five plants.
How to plant Mirabilis jalapa
The easiest way to grow Mirabilis jalapa is to buy dormant tubers, sold in winter to early spring. For flowers from early to mid-summer, plant in large pots and keep under cover until all risk of frost has past, before moving outside. Alternatively, plant outdoors in mid- to late-spring for a later flowering start. Plant tubers 8-10cm deep and spaced 15-20cm apart in a good multi-purpose potting compost. Plants raised indoors need to be gradually hardened off or acclimatised to the outdoors by standing out for increasing periods of time.
How to care for Mirabilis jalapa
Plants in the ground need little attention apart from a monthly feed with liquid fertiliser high in potash, such as tomato food. Those in pots need regular watering as well as a monthly feed, though take care not to over-water or the fleshy roots could rot.
To overwinter Mirabilis jalapa, continue feeding and watering for several weeks after flowering, still taking care not to over-water, until the leaves start to die back. Allow the growth to die completely before cutting off the stems just above the ground and digging up the roots. Store in trays of compost kept barely moist, in a cool frost-free place. In late winter, repot the roots into moist compost and place in a warm spot to start into growth.
How to prune Mirabilis jalapa
No regular pruning required.
How to propagate Mirabilis jalapa
Collect the black seeds from spent flowers in late summer, and store them in a paper envelope to sow the following season. Sow seed indoors in late winter to early spring, in a heated propagator set to 18ºC. Mirabilis jalapa seeds need light to germinate, so cover with ½ cm of perlite or vermiculite, rather than compost. Once seedlings have germinated and have formed true leaves, transplant to individual 8cm pots and grow on, still using bottom heat if you need to, until well established.
Alternatively, dig up, divide and replant the tubers in spring.
Pests and diseases
Mirabilis jalapa is easy to grow and trouble-free. Aphids may be a problem, particularly on plants growing indoors. Inspect leaf undersides regularly and also look out for aphid honeydew on the surface beneath the plant. A variety of treatments can be used to combat aphids, though often hand-squashing is all that’s necessary if spotted early.
Advice on buying Mirabilis jalapa
- The dormant tubers of Mirabilis jalapa bulbs, as the tubers are sometimes referred to, are available along with spring-flowering bulbs in some nurseries and garden centres, although are not widely available
- Some online suppliers also supply the tubers but specialist nurseries may have more choice
- Check the tubers are firm and free from rot
Where to buy Mirabilis jalapa online
Frequently asked questions
Is Mirabilis jalapa annual or perennial?
Mirabilis jalapa is perennial in frost-free environments but is usually treated as an annual in the UK, where winter temperatures are rarely sufficiently mild for plants to survive outdoors. To keep this plant over winter it is necessary to lift, dry, and store the tubers in a frost-free place to replant the following year.