How to Grow and Care for Allamanda Indoors

Allamanda, also known as golden trumpet, is typically grown as a shrub outdoors in warm, moist climates but it can be grown as a houseplant for its showy blooms. This tropical plant needs significant warmth and moisture indoors to thrive, as well. When grown indoors, opt for the Allamanda cathartica variety, which features large buttery yellow flowers with a brown throat and an exhilarating fragrance that hides among large, glossy leaves. When this rapidly growing plant is in full bloom, it's likely to be covered with these 4-inch flowers and will be the pride of your houseplant collection. Allamanda is toxic to humans and animals.

Can You Grow Allamanda Inside?

Allamanda is not a very forgiving plant in the home environment. Plants that are exposed to cold drafts or denied adequate water tend to drop leaves with impunity. Also, they will not bloom unless there's adequate warmth. For these reasons, many people in colder latitudes reserve allamanda for the greenhouse or conservatory instead of the inside of a home with dry winter air.

How to Grow Allamanda Indoors

Sunlight

Allamanda prefers strong light, including some direct sun. The plant can be adapted to full sun, or it can be grown successfully in an east-facing window with only a few hours of the morning sun.

Temperature and Humidity

Since allamanda likes warm, tropical temperatures, the most dangerous period for the plant is winter when even warm houses tend to become exceedingly dry. In these cases, it's essential to mist your plant frequently to help it keep its leaves—dropping leaves is not a good sign or a sign of natural growth cycles.

Watering

Water liberally throughout the summer, making sure your growing pot has good drainage. It's also helpful to mist every other day or so to provide adequate humidity. In the winter months, reduce watering but don't let the plant dry out, and make an effort to keep the root ball warm.

Fertilizer

Feed allamanda with a weak liquid fertilizer throughout the growing season. Cut fertilizer back to once a month or so in the winter.

Pruning and Maintenance

Prune allamanda in midspring before the plant flowers. To neaten the plant and keep it compact indoors, you can trim it back at any time without harming the plant. Pruning dead or unhealthy leaves allows for new growth so allamanda can grow bushier.

Container and Size

Plant allamanda for indoors in a large container that is at least 4 gallons. The pot must have many drainage holes. Choose an unglazed clay or terra-cotta pot so the container does not stay excessively moist. However, to increase the level of humidity in the air around the plant , place it on a pebble tray and water. Do not let the bottom of the pot become immersed in the water.

Potting Soil and Drainage

A rich, peat-based potting soil with excellent drainage is beneficial for growing allamanda indoors.

Potting and Replanting Allamanda

Repot allamanda in the spring when new growth emerges—this is also a good time to take cuttings. When you repot, place the plant into a larger pot and provide a plant support ring, trellis, or other means of support if necessary. Allamanda can be grown as a low shrub, but it does best if allowed to grow up a simple support and trail slightly, which seems to show off its blooms to maximum effect.

Moving Allamanda Outside for the Summer

Potted indoor allamanda plants can be moved outside for the summer when it's consistently warm. The pot needs to be gradually acclimated to the outdoors.

Considerations

Place the indoor pot of allamanda in full sun or partial shade in the warm weather. It will need between 4 to 6 hours of direct sunlight daily but it can take even more sun than that. Continue to water, fertilize, and prune allamanda even when it is outdoors.

When to Bring Allamanda Back Inside

Move the plant back inside when the nighttime temperature gets down to 40 degrees Fahrenheit.