If you enjoy teaming up different annual combinations in containers, lobelia will quickly become a favourite. Here’s some tips on growing lobelia in your garden so it looks its best.
1. Pick a type that works for you
- Lobelias grow to 15 centimetres (six inches) tall, but varieties vary in growth habit.
- Some form rounded mounds, while others are more intent on spreading, making them suitable for cascading over the edges of containers.
- If you want to use lobelia to edge a bed, choose a mounding variety.
- Choose a cascading variety for containers, baskets, or for planting at the top of a stone wall.
2. Give them plenty of friends
- Petunias have similar weather preferences, so the two make an unbeatable combination in beds or containers.
- Yellow dwarf marigolds are also excellent companions.
- Lobelia is a great way to hem a patchwork of snapdragons or zinnias.
- Weave lobelia among silver-leaved dusty miller for a neat, trouble-free edging in foundation beds.
3. Start with bedding plants
- Lobelias need an eight to ten week start from seeds before they reach transplanting size. So in this case, bedding plants are a good buy.
- Keep the soil in their containers moist until you plant them.
- Set the bedding plants in the garden after your last spring frost date, spacing them 15 centimetres (six inches) apart.
- Lobelias grow best in a cool spot with partial shade in areas where days are often above 25°C.
- Before planting lobelias in beds, mix a balanced, organic or controlled-release fertilizer into the soil.
- Fertilize pot-grown lobelias every two weeks during the growing season, using an all-purpose plant food.
4. Rejuvinate them in the midsummer
- In midsummer, you can rejuvenate lobelia by cutting the plants back by half their height. Reapply fertilizer and water them well.
- This is worth a try in all climates, but it may not succeed in hot, humid areas, where lobelias often wither away in July.
5. Propagate for the next season
- Lobelias are easy to propagate. Just root 10 centimetres (four inches) long stem cuttings taken at any time.
- Remove leaves from the lower five centimetres (two inches) of stem. Insert the cuttings halfway into moistened potting soil.
- Set the containers in a shady spot. Keep the soil moist until new growth indicates that they’re rooted.
- Plants can be cut back and wintered over indoors on a sunny windowsill. Here, they’ll keep on blooming and be ready to go out to the garden the next spring.
Lobelia is the perfect plant for the edge of anything, and can add splashes of blue to your garden. For best results, take care of them while they’re getting settled and mix them in with different flowers. This will give your garden a whole new palette.