Lobelia plants provide colour to the garden, whether you plant a mounding or trailing variety. Most annual lobelias are short plants with small blue flowers, making them suitable for hanging baskets, borders and mass bed planting. There are also pink, white and purple lobelias, which gives you a choice of colours to complement your other garden plants. Lobelia is fairly low-maintenance, requiring similar care as other flowering annuals in the garden.
Plant lobelia in a bed that receives at least six hours of bright sunlight a day. Hang baskets and set pots in south- or east-facing areas so the lobelia receives the required amount of light. Choose areas with afternoon shade to protect the plants from the heat of summer.
Water lobelia when the top 1 inch of soil begins to feel dry in the bed or pot. Moisten beds to a 6-inch depth one to two times a week. Water potted lobelia until the excess moisture drains out the bottom drainage holes. Potted lobelia may require daily watering during hot weather.
Spread a 2-inch layer of wood chips or other organic mulch over the soil and around the plants in garden beds. Mulch prevents weed growth while also preserving moisture between each watering.
Fertilise potted lobelia every six weeks with a general-purpose, soluble fertiliser. Fertilise bedding plants with a 10-10-10 analysis fertiliser in spring and again at midsummer at the rate recommended on the label.
Remove the spent blossoms from the lobelias to encourage further flowering and to keep the plants neat and attractive. Pinch off the spent blooms beneath the flower heads and dispose of them. Pinch back overgrown branches to the desired height to maintain even mounds of foliage and flowers.
Lobelia doesn't require watering if there is more than 1 inch of rainfall during the week.