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Flowers, Xeriscape Gardens

Lobelia Laxiflora Care: Growing Mexican Bush Lobelia


7 min read

Lobelia laxiflora is a sprawling perennial with medium green leaves and colorful tubular flowers. Also known as Mexican Lobelia, the plant is native to Mexico, Central America, and Southern Arizona.

As a care-free perennial plant with bright orange and red flowers, it grows best in warm and dry regions – a perfect plant for xeriscape gardens. As gardeners, we love these species as they’re beautiful, easy-to-grow, and attract colorful hummingbirds.

Quick Care Guide

Flower of the Lobelia laxiflora, perfect for hummingbirds
Flower of the Lobelia laxiflora, perfect for hummingbirds. Source: jerryoldenettel
Common NameMexican bush lobelia, Mexican cardinal flower, Sierra Madre lobelia, loose flowers, drooping lobelia
Scientific Name Lobelia laxiflora
FamilyCampanulaceae
Height & Spread2-3′ tall and 4-6 wide
LightFull Sun
SoilWell-draining, rocky, deep
WaterLow
Pests & DiseasesAphids, spider mites, whiteflies

All About Lobelia Laxiflora

Lobelia laxiflora is commonly referred to as Mexican bush lobelia, Mexican cardinal flower, Sierra Madre lobelia, loose flowers, and drooping lobelia. This plant is a member of the family Campanulaceae, or the bellflower family.

This lobelia is native to South America, Central America, and southern parts of North America, as far north as Arizona. In most of its native areas, particularly in Mexico, the plant grows best in alpine regions in full sun meadows or partial shade forest floors.

The perennial herb with green leaves can grow up to 2-3″ tall with arching stems that bear gracefully long and narrow leaves. The inflorescence grows up to 16″ long and blooms in late spring and summer. The dainty blooms have a tubular base with narrow corolla from which the anthers protrude. Its flowering season is May through August.

Mexican lobelia is a specific host for the hummingbird mite, which feeds on the nectar and pollen of the plant. The lifespan of the flower — about a week — gives the hummingbird mite just enough time to feed, lay eggs, and complete its cycle of reproduction.

Lobelia Laxiflora Varieties

While Lobelia laxiflora is its own species, it belongs to the Campanulaceae family and there are many different kinds of Lobelia that are quite similar to the laxiflora.

  • Lobelia cardinalis, for example, is known for its dark-red tubular flowers and rich green foliage.
  • Lobelia erinus is also a famous species that produces tiny purple blooms and is native to South Africa.
  • Lobelia inflata or the Indian Tobacco has toothed, ovate leaves that grow up to 3″. It has beautiful violet flowers tinted with yellow that appear in mid-summer.

Lobelia Laxiflora Care

Mexican Cardinal Flower along Sierra del Sur
Mexican Cardinal Flower along Sierra del Sur. Source: jerryoldenettel

As a carefree plant that grows well in sunny areas, Lobelia laxiflora requires the same care and maintenance as other herbaceous plants. The following are the optimal conditions it needs to grow.

Light and Temperature

The plant should be grown under full sun or partial shade, preferably through a south or west-facing window if grown indoors. Avoid a north facing window.

It’s suited for USDA Hardiness Zones 9-11. In areas with cooler climates or slightly harsh winters, the plant will require overwintering by planting in a container and putting under cover. The plant can withstand short periods of temperatures down to 20°F.

Water and Humidity

Younger plants need deep watering throughout the summer. However, once the plant has established, it is drought-tolerant and won’t require frequent watering.

In fact, excessive water causes the plant to rapid spreading and it may become aggressive in the garden. Less water keeps the growth in check while allowing the blooms to flourish.

Soil

The plant needs well-drained, moist soil for optimal growth. Sand and loam are the best choices with a slightly alkaline pH to keep the plant thriving through the seasons. Rich potting soil with organic compost and a pH of 6-7.5 is an optimal choice. If mixing your own, feel free to add a bit of sand or perlite to the mix to loosen it up.

Fertilizer

The plant works best with liquid fertilizers that are high in phosphorous. Treat it with a high-quality fertilizer once a month to sustain optimal growth, dialing it back in winter.

Transplanting and Repotting Lobelia Laxiflora

The plant can be transplanted in spring right before the new growth starts. If you’re growing the plant inside a container, don’t transplant unless it requires a larger pot. You can either sow the seeds directly in the garden or start indoors and then transplant it later on.

To grow this indoors, choose a time about 10-12 weeks before the last frost in your area. Choose a small pot and spread the tiny seeds. Water thoroughly and place the pot in a well-lit, warm area.

The seedlings will pop up within 1-2 weeks, which is a good time to thin them out. Once the plant is at least 2-3″ tall, and the frost is completely gone, transplant it to your garden. Space them at least 5-6″ apart.

Mexican Bush Lobelia Propagation

The Mexican cardinal flower can be propagated in late spring when you’re grooming the plant. Measure and cut at least 4-5 inches of the branches while simultaneously removing the leaves.

Now, take a clay pot and prepare it nicely with well-drained potting soil. Hydrate the soil and then gently push the fresh cuttings about halfway into the container.

Lightly mist them at least twice a day and water the container every alternate day. Once they take root, it’s time to replant them in new pots.

When you’re sure that the last frost has died, carefully transplant the young roots to an outdoor ground.

Lobelia Laxiflora Pruning

Simply, pinch off any dying or wilting flowers to encourage new blossoms. And, cut down any dead stem or foliage following the first freeze.

Troubleshooting

When supported by a well-draining soil, sufficient water, and lots of sun, this perennial plant grows without any problems. However, it’s susceptible to a few pests and diseases.

Growing Problems

The only issue you might face outside pests and diseases is aggressive growth in the garden. Remember, this plant doesn’t need ton of water, and excessive irrigation may promote overgrowth, and overtaking of other nearby plants. Reduce watering if this has been an issue.

Pests

Spider mites, white flies, and some species of aphids are three pests that can threaten the growth of this plant. To eliminate spider mites, mix a few drops of rosemary oil in water and spray the mixture over the leaves. You can also use a insecticidal soap to kill the insects.

White flies can be easily blasted away with a jet of water. You can then follow up with an insecticidal soap over the stems and leaves to ensure the plant’s safety.

Aphids like new stems and soft leaves. Blast them with a strong stream of water as well. This will effectively kill the aphids.

Diseases

Although there are no specific diseases, in damp, mild condition, the crowns of the plant can rot. Therefore, it’s extremely important to ensure minimal water once the plant has established.

Frequently Asked Questions

Q: Is the Mexican cardinal flower a good plant for a pollinator garden?

A: Certainly. It is an excellent choice as its colorful flowering and bloom size attracts hummingbirds, butterflies, and other beneficial insects.

Q: Is the plant tolerant to drought?

A: Yes, this species is drought-tolerant with a long blooming season.

Q: Can it be grown in a container?

A: Yes, it can be grown inside a pot; however, make sure the soil remains well-drained and moist.

Q: How long will lobelia last?

A: Each of the Mexican lobelia flowers last for one week. These bloom May through August.

Q: Is lobelia OK in full sun?

A: Mexican lobelia loves full sun. Partial shade is also acceptable.

Q: Do lobelia come back every year?

A: Yes. All lobelias are perennials, including Mexican lobelia.

Q: What problems do lobelia have?

A: L. laxiflora can get out of hand in the garden if not kept in check.

Q: Should you deadhead lobelia?

A: You certainly can deadhead Mexican lobelia, and doing so will promote more blooms.

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