When To Plant Lobelia In The UK


Lobelia has long been the UK’s favourite edging plant for summer bedding schemes. The trailing variety is also one of the most popular hanging basket plants too.

It is often paired with alyssum and the traditional varieties were blue or violet, but the colour range has now been extended to reds and pinks.

Usually, it is sold in a six-pack bedding tray and available for the public to purchase sometime in April. But lobelia shouldn’t be planted then as there is the danger that a frost could kill this tender annual plant off before the season has already started.

Lobelia is best planted outside in the UK in late May or early June with the rest of your summer annuals when the risk of frost should be long gone.

Where To Plant Lobelia


Lobelia can be planted in full sun or partial shade where the soil is moist but well-drained.

Unlike most summer bedding plants, lobelia doesn’t mind the cooler conditions that we receive here in the UK.

Watering Lobelia

Lobelia requires frequent watering during the summer months as their short roots stay close to the surface of the soil.

Water your lobelia slowly saturating the soil to a depth of around six to eight inches, then allow the top two inches of the soil to dry before watering again.

Lobelia planted in poorly drained, soggy soil may get root-rot or other fungal diseases.

Feeding Lobelia


Lobel will benefit from a balanced liquid feed every two weeks when first planted. Then switch to a high potash feed in the height of the summer feeding every two weeks.

Deadheading Lobelia

To make sure flowering doesn’t get disrupted deadhead your lobelia frequently. Tips should be pinched back to promote bushier growth.

When flowers are spent prune the entire plant back by half an inch to promote more blooms.

Why Is My Lobelia Turning Brown?


Lobelia doesn’t care for intense heat or drought and is not designed to function under extreme conditions, so more often than not the leaves will turn brown and curl up from the outer edge inwards when too hot.

Growing Lobelia From Seed

  • Lobelia seeds can be sown from January to April to give you a summer display.
  • Sow singly or in small groups spaced around half an inch apart in trays of good seed compost.
  • Press the seeds gently into the surface and germinate at a temperature between 15-20°C (6-68°F).
  • Do not cover the seeds in compost and keep in a light yet shaded position, maintaining moisture.
  • Germination should take between 10 to 20 days.
  • Transplant seedlings when large enough to handle, spacing them 2 inches (5cm) apart in trays of potting compost and grow on.
  • Acclimatise to outside conditions 2 to 3 weeks before planting outside in your garden when the risk of frost has passed.

Lobelia Facts

Native to South Africa and its name derives from Matthias de Lobel a sixteenth-century Flemish botanist.

Lobelia is classed as a herb and was once smoked by Native Americans to treat asthma. It is also known as pukeweed, doctors used to prescribe it to induce vomiting.