Updated at: 11-05-2022 - By: Sienna Lewis

Prune lobelia properly by keeping three things in mind. However, it’s important to note that you must thoroughly investigate the lobelia species before purchasing it. A greenhouse provides a more stable habitat for plants than a garden does, thus trimming should not be the end of plant care.

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Pruning, on the other hand, is necessary to maintain the health of the plants and to keep the area tidy. In the absence of maintenance, lobelias can quickly take over an area. Remember that lobelia can be harmful, especially if you have children or dogs close.

Things You Will Need

  • shears for pruning
  • Soak the dishes with dish soap.
  • Household disinfectant
  • a towel made of paper

How to Deadhead Lobelia

According to the Ohio State University Extension, deadheading plants not only improves the appearance of the garden, but it also encourages more blooming throughout the season. When the plant is in full bloom, remove the deadheads. To deadhead, either remove the faded flower stalks one at a time or prune the entire plant in the middle of the summer. The latter method is the most efficient.

If you’re deadheading individual stems of flowers, make sure they don’t protrude above the foliage. If it rains, snip the grass at an angle so that water will run off the cut. Instead, shear the entire plant in half once its flowers have stopped blossoming and dried up in midsummer. Due of the limited lifespan of the lobelia perennial, many gardeners leave a few flower stalks in place to set seed for the following season’s collection and sowing.

How to Cut Back Lobelia

Every year, the lobelia dies back due to the frost. Overwintering lobelia in the garden depends on the dead growth, which looks unsightly but serves a vital purpose. Frost-damaged growth should be left in place over the winter to safeguard the lobelia’s roots, according to Cornell University and Oregon State University Extension. A new growth can be removed next spring, when it heats up and new growth begins to develop at plant bases.

Take a 45-degree angle and snip off the old growth as close to the root as possible with sterilized and sharp pruning shears, taking care not to cut off any new foliage that is just beginning to emerge from the base of the old stalk. Remove any dried leaves that dropped off while pruning by gently raking your fingers through the newly sprung leaves. Dead leaves and stems should also be raked away from the plant’s base. Consider any new offsets that may be forming around the base of the plant, as these can be separated and replanted in the fall.

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How to Clean Pruning Shears

When it comes to garden upkeep, cleaning and maintaining tools like pruning shears are two of the most critical yet often forgotten duties. Because a sharp edge is less likely to damage the plant’s stems, and because clean shears are less prone to transfer diseases, pruning shears should be kept sharp, clean, and sanitary. Every couple of years, if possible, have the blades professionally sharpened or replace the shears if they have pitted, nicked, or really dull edges.

Rinse pruning shears in hot water with a tiny amount of dishwashing soap after each use. Thoroughly clean the hinges and any other areas where plant debris could accumulate. Use hot water to clean the shears. Undiluted household disinfectant should be used to disinfect the freshly cleaned blades. Shears can be reused after disinfectant has been removed with a paper towel.

How To Prune Lobelia For Beginners


When pruning lobelia, the first thing you need to master is pinching. Especially if you’ve just planted the plant, you don’t need to immediately trim or cut back the plant To stimulate branching, pinch the tips of a fresh plant and watch it grow into a bush.

The top leaves of your newly planted lobelia can be pinched off until the second bud appears on each stalk. Squeeze the tip of the stem with your fingertips. This way, additional branches with flowers will sprout from these places, creating a fuller lobelia plant.

Early spring is the ideal time to pinch lobelia plants. Pinch back any newly emerging stems that are six inches or longer. Otherwise, you should wait until newly planted lobelias have established roots before pinching them.


In addition to pinching, you’ll need to trim your lobelia plant at some point, and scissors are an excellent tool for the job. Keep the plant clean and well-groomed by performing this maintenance task on a regular basis. In contrast to pinching, you don’t have to wait until spring to trim lobelia; you may do it all year round.

As an exception, some varieties of the plant, particularly the spiky ones, should be completely faded before you cut their stems. Use withering petals as a signal to cut your plant in half, or remove the faded blossoms, if you prefer. As with pinching, cutting near to a leaf or a bud encourages a broader look.

Cutting back

Cutting the lobelia back is the final step in pruning. Trimming, on the other hand, is a light pruning that may be done at any time of the year to maintain the plant looking tidy. After the plant has finished blooming, or after each flowering phase, you can perform this procedure.

To enhance and extend blooming, cut back lobelias to remove spent flowers that will release seeds. Pruning heavily benefits the plant’s health as well as its look. To stimulate fall blooming, some gardeners even leave some species of lobelia in the garden during the summer and then prune them back.

Caring For Lobelia

After pinching, pruning, and cutting back the lobelia, there is still a lot of work to be done. Placement of lobelias is just as important as learning how to prune them appropriately. In the greenhouse, this can be easily accomplished because the inside conditions are stable and can be adjusted to match the weather outside.

When the final frost is 12 weeks away, you can start growing lobelias in the greenhouse and wait until there is no risk of frost before transferring them to the garden. The recommended distance between plants is six inches, and a location in direct sunlight should promote development.

A wet and healthy soil is ideal for successfully growing Lobelia. However, if the weather is really hot, you can fertilize the plants once a month to increase blooms. You just have to watch out for overwatering and exposing the lobelia to high and harsh temperatures.

Best Lobelia Varieties To Grow

If you’re cultivating lobelia, you’ll need to know what kind of lobelia you’re dealing with and what it needs. Edging lobelias, large blue lobelias, cardinal lobelias, and a hybrid of the last two are among the most common. If you have edging lobelias, you may not need to deadhead them because of their habit of trailing.

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Blue lobelias, on the other hand, are known for their long blooming periods, and the great blue lobelia is one of the most popular varieties. The scarlet-red blossoms of the cardinal lobelias make them popular as well. Finally, both of these hybrids have a wide range of colors and an extended bloom period throughout the summer.

Consider the fact that lobelias come in a variety of forms, including annuals and perennials. Also, you can discover sensitive annuals, mounding lobelias, and half-hardy annuals. Lobelia plants come in a variety of colors, including lilac and tropical.


Lobelia plants’ beauty and health are greatly influenced by their upkeep. As a result, if you want to keep your lobelia plants happy, you’ll need to learn how to prune them. If you don’t already have them in a greenhouse or other controlled environment, make sure you squeeze, trim, or cut back any plants you already have to get the most out of them.

Keep in mind that some lobelia varieties self-clean, so deadheading isn’t always necessary. Maintaining a tidy appearance by cutting back on the plants’ growth is good to their flowering and health. Pinch back newly planted lobelias to encourage branching and fuller development.