Complete Advice for Growing Lobelia
Planting, Ongoing Care, Pests & Diseases and FAQ
Dainty looking, easy to grow flowers of annual lobelia are used to great effect as fillers and spillers in beds, borders, hanging baskets and container displays. Perennial lobelia have larger flowers and are a great filler for your containers or boarders growing up to 1 meter high!
The best known have bright blue flowers with tiny white centres, but purple, pink and white-flowering types are widely used too.
Annual Lobelia have two main varieties - Bush/Upright Lobelia used as a compact but free flowering edging plant producing compact globes of flowers and Trailing Lobelia ideal for using in hanging baskets and window boxes and trailing to a length of between 10-50 cm.
Planting Lobelias
Where to plant Lobelia?
Lobelia require a sunny/part shady spot in a well-drained fertile soil or compost that maintains moisture, they look great in hanging baskets, boarders and containers a like. Lobelia will florish all summer long until the first frosts. Annual lobelias can be discarded after the first frosts to make way for your winter flowering annuals.
Perennial Lobeila will die back, however, new growth will start to appear again the following spring. We advise growing your perennails in full sun to get best results, however they will tolerant some shade. As some perennail lobelias can grow up to a meter high, these are best to be planting in your garden boarders and containers.
When to plant Lobelia?
Lobelia plug plants will need growing on, when you recieve your lobelia plug plants give them a drink of water as they do not like drying out! Using a good quality peat free compost, transfer the individual plugs into 6, 9 or 12 cell trays, see here for out ranges of pots and trays. For packs of 20/40 and our wholesale 350 plug plants gently remove the small plugs from the tray by pushing up from the bottom of the tray using a pencil.Check plants regularly and do not allow the compost to dry out completely. Lobelia plug plants need to be grown in a bright, warm frost free place like a greenhouse or windowsill indoors before planting outside in May/June depending on frost warnings in your area. If your perennial Lobelia have flowered early and are fading by the end of june, cut these hard back to around 18cm (5"), this will encourage these to flower once again in the same year!
How to plant Lobelia.
For annual Lobelia once they are ready to plant outside, space at approx 4-6" (10-15cm) apart in a moist soil if planting into a container or garden boarder. For a 12" or 14" hanging basket 3-5 plants should be sufficient when used with other plants. When planting perennial lobelia we recommend spacing approx. 30-36cm (12-14') apart.
Ongoing care for Lobelia
Lobelia are used in many hanging basket displays which are generally placed in a sunny position. If you can give them some afternoon shade especially in prolonged hot weather, this will keep the basket from becoming too dry and the lobelia plants from scorching, especially if the basket is beginning to dry out. Morning sun and afternoon shade is ideal for Lobelia.
Watering Lobelia
Daily watering is recommended in summer to keep hanging basket flowers including lobelia blooming throughout the summer months.
Trailing and bush varieties of lobelia have shallow roots, so because their roots are near the surface of the soil, watering is essential to stop them drying out. Once they are depleted of moisture, lobelia will wilt and quickly dry out. Stems and flowers will shrivel and brown. If this happens mid-season it is worth cutting back by a third and seeing if the plant will revive.
Feeding Lobelia
Aim to give lobelia plants a feed every fortnight using such as a liquid feed like Neudorff Organic Plant Feed as instructed on the product, throughout the growing season as they are hungry plants.
Deadheading Lobelia
Lobelia are self-cleaning and do not require deadheading. Pruning is not necessary unless some light cutting back to tidy up the plant is needed for trailing varieties that may become straggly in mid-summer.
Staking Lobelia
Annual lobelia, either the trailing or the upright, bush variety are compact plants that do not need staking. Some of the taller perennial lobelia might need some staking toward the end of the season just for some additional support.
Dividing Lobelia
Dividing is not necessary. Annual Lobelia are shallow rooted, fine stemmed plants that are bred to remain compact throughout the growing season. Perennial Lobelia as best not to be divided, however if you chose to divide the best time would be spring rather than autumn.
Overwintering Lobelia
At the end of the flowering season annual Lobelia are easily removed and can be placed on the compost heap to rot down. Perennial lobelia are best to be cut back in the autumn and given a mulch to protect the crown of the plant over the winter months.
Pests and Diseases
Tips to help stop common pests and Dieases.
Starting with the best plant hygiene is always key when growing on your plug plants. Disinfecting your used pots, trays and gardening tools before you start with a solution like our Natural Citrus Cleaner will help fend off any unwanted pests and diseases from the get go.
Common Pests that eat Lobelias.
Lobelia erinus is generally free of pests. Deer and rabbits do not tend to eat lobelia. Lobelia may be susceptible to slugs and snails, although this isn't the first plants they will go for!
Common Diseases that can affect Lobelias.
Whilst growing on lobelia plug plants in the greenhouse, ensure that air can flow freely around the plug plants to prevent damping off on the stems above and below the soil surface. Maintaining an even soil temperature can help to alleviate this issue.
Lobelia can suffer from root rot if the soil is too wet or waterlogged. Water lobelia from the base where possible and try not to let water get onto the foliage.
Freuently Asked Questions
What are the common Problems that can affect Lobelia?
Lack of correct watering is the most common problem with lobelia. If left for too long without water at the roots, the whole plant can perish. Lobelias have shallow roots and will not search out water from deeper within the compost or soil.
Trailing lobelia are used in many hanging basket displays and can suffer from lack of water if strong winds dry out the compost. Being shallow rooted they will be the first plants to react to compost drying out so keep an eye on them and water baskets regularly.
Why is my Lobelia plant wilting?
This is caused by lack of water resulting in the soil/compost drying out. The key is to water moderately but regularly.
Why have the leaves and stems on my Lobelia turned brown?
Prolonged sun exposure along with lack of water will be the probable cause. Cut back the affected area to encourage new growth. In some cases where damage is severe the plant may need to be discarded altogether.
Can I overwinter Lobelia?
Lobelia erinus is treated as an annual bedding plant in the UK and may be discarded at the end of summer after flowering. Place plants onto the compost heap to rot down. Perennial Lobelia, like the varieties you can find here can be over wintered (see advice above).
Are Annual Lobelia scented?
Although producing many beautiful flowers, lobelia are not scented.