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, its 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.
With its vibrant yellow trumpet-shaped blooms, alamanda makes a beautiful addition to tropical gardens. To keep your alamanda plant looking its best and flowering abundantly, proper fertilization is important. But there are some dos and don’ts to keep in mind when feeding this tropical flowering vine. Let’s go over when and how to fertilize alamanda for optimal growth and performance.
Alamanda scientifically known as Allamanda cathartica is a shrub or vine native to Brazil. It produces shiny green leaves and stunning yellow flowers that gave rise to its other common name – golden trumpet vine. There are around 10 alamanda species, but A. cathartica is the most popular ornamental type grown for its floral display.
With its tropical origins, alamanda thrives in warm climates and bright sunlight. It can tolerate some drought once established but grows best with adequate water and humidity. This plant can reach heights up to 20 feet as a vine, or it can be pruned into a more compact shrub form. Proper fertilization is key to fueling growth and abundant blooms.
Do Fertilize at the Right Time
Fertilizing at the optimal times helps ensure alamanda gets the nutrients it needs for the best performance.
Spring and summer – Fertilize actively growing and flowering plants every 2-4 weeks during the warmer months of spring and summer.
Fall preparation – Apply fertilizer monthly in fall to strengthen plants before cooler weather arrives.
Stop in winter – Discontinue fertilizer over winter when plants are dormant. Resume feeding as growth resumes in spring
After pruning – Give a dilute fertilizer dose after major pruning to aid regeneration of new shoots and leaves.
Do Use a Balanced, Water-Soluble Fertilizer
Look for a fertilizer with equal proportions of nitrogen (N) phosphorus (P) and potassium (K). This complete nutrition supports the leaves, roots, and flowers.
Nitrogen (N) – Fuels plant growth and green foliage.
Phosphorus (P) – Aids root, shoot, and flower development.
Potassium (K) – Important for disease resistance and drought tolerance.
A 10-10-10 or 20-20-20 NPK formula works well. Choose a water-soluble product for easy dilution and plant absorption. Apply according to label rates.
Do Fertilize Before Bloom Period
Alamanda produces flowers on new growth emerging in spring and summer. Fertilizing in early spring will provide nutrients needed for the flush of new growth that leads to flowering.
Give plants a good feeding 2-4 weeks prior to the expected bloom time. This fuels the plant for the high energy demands of producing abundant flowers.
Don’t Over-Fertilize
While regular feeding is beneficial, it’s possible to overdo it with fertilizer on alamanda plants. Using too much or applying too frequently can cause fertilizer burn.
Signs of over-fertilization include:
- Tip and margin leaf burn
- Poor flowering
- Root damage
- Stunted growth
Reduce the fertilizer concentration and application frequency if you see these issues. It’s better to under-feed than overdo it.
Do Allow Soil to Dry Between Waterings
After applying fertilizer, allow the soil to partially dry out before watering again. This gives the roots time to absorb nutrients.
Wet soil prevents oxygen from reaching the roots. Fertilizing overly moist soil can also burn the roots with concentrated chemicals.
Let the top inch or two of soil dry between waterings when using fertilizer. Slow-release products are less likely to cause burn.
Don’t Fertilize a Dry or Stressed Plant
If an alamanda plant is wilted from drought or has stopped active growth, do not fertilize it. Fertilizer on a distressed plant can damage roots and leaves.
Instead, correct any underwatering, drainage issues, disease problems, etc before feeding the plant again. Fertilize only when the plant is healthy enough for active growth.
Do Watch for Nutrient Deficiencies
Keep an eye out for signs of missing nutrients like:
- Yellowing leaves – Nitrogen deficiency
- Poor flowering – Lack of phosphorus
- Browning leaf tips – Potassium deficiency
Target fertilize to correct any deficiencies. For example, use a nitrogen-rich fertilizer to green up yellowing leaves.
Do Use Organic Mulch
Organic mulch like wood chips or bark around your alamanda plants provides nutrients as it decomposes. This mimics the natural mulch of a forest floor.
Mulch also conserves moisture and keeps soil evenly moist after fertilizing. 2-3 inches of mulch is ideal. Replenish as the mulch decomposes.
Do Scratch Fertilizer into the Soil Surface
Dry fertilizer that is simply sprinkled atop the soil can easily wash away with irrigation or rain. To help the nutrients penetrate into the soil, lightly scratch or till granular fertilizer into the top 1-2 inches of soil.
This also prevents fertilizer from contacting the leaves and causing burn. Once scratched in, water thoroughly to dissolve the fertilizer and carry it to the root zone.
Don’t Fertilize Near the Main Trunk
Avoid mounding fertilizer right around the main stem and trunk. This risks burning the living bark tissue.
Keep the fertilizer a few inches away from the trunk, and scratch it into the surrounding soil instead.
Do Adjust Frequency for Your Plant’s Needs
There’s no fixed fertilization schedule that suits every alamanda. The ideal frequency depends on factors like:
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Plant age – Younger plants need more fertilizer.
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Growth rate – Fast growers use more nutrients.
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Soil type – Lean soils require more fertilizer.
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Environment – Plants in full sun need more nutrients.
Adjust your fertilizing routine based on monitoring your plant’s specific needs and growth patterns.
Don’t Fertilize Blooming Plants
Hold off on fertilizing alamanda while it is actively flowering. The high phosphate in fertilizers can cause flower buds to drop.
Wait to fertilize until after the blooming period is finished. Focus on watering and trimming while the plant is covered in flowers.
Do Test Soil Nutrient Levels
Home soil test kits are an inexpensive way to analyze your soil’s pH and nutrient content. This helps determine what amendments your soil may need for optimal alamanda growth and performance.
Adjust fertilization, pH, and soil composition based on the test results. For example, add lime to raise low pH or more phosphorus if your soil is deficient.
Don’t Assume More Is Better
Using a very concentrated or high-rate fertilizer does not mean your alamanda will grow bigger and faster. Excess fertilizer can accumulate in the soil and cause damage.
Stick within the recommended concentration and application rate for whatever fertilizer you choose. More is often not better when it comes to fertilizing.
The Best Fertilizer for Alamanda Plants
There are lots of fertilizer options out there. Look for these characteristics in choosing the best formula for your alamanda:
- Balanced NPK ratio like 10-10-10 or 20-20-20
- Soluble powder or liquid for quick uptake
- Organic if possible – compost, worm castings, etc
- Contains micronutrients – iron, magnesium, zinc, etc
- Follow label instructions for dilution and timing
With a quality complete fertilizer and proper application schedule, you can optimize your alamanda’s growth and flowers.
Fertilizing is important for alamanda’s performance, but it’s easy to overdo it. Follow the dos and don’ts – fertilize regularly at the right times with a balanced formula, but don’t over-fertilize or feed stressed plants. Customize the frequency and concentration to your specific growing conditions. With careful fertilization, you can keep your alamanda plants looking lush, healthy, and floriferous year after year.
How to Grow Allamanda Indoors
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.
Watering
Water liberally throughout the summer, making sure your growing pot has good drainage. Its also helpful to mist every other day or so to provide adequate humidity. In the winter months, reduce watering but dont let the plant dry out, and make an effort to keep the root ball warm.
Fertilizing Our Garden! // Garden Answer
FAQ
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