Lobelia cardinalis
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Lobelia cardinalis

زهرا · Cardinal Flower · Scarlet lobelia · Red Cardinal Flower · Cardinal Lobelia

Tier 1 Difficulty: medium Water: moderate Light: full_sun Toxicity: high
Water every
7 days
0
Soil pH
6–7
Hardiness
Zone 3–9
Click count
1,240
Observations
1,972

Description

Source: leafsnap

Lobelia cardinalis, the cardinal flower (syn. L. fulgens), is a species of flowering plant in the bellflower family Campanulaceae native to the Americas, from southeastern Canada south through the eastern and southwestern United States, Mexico and Central America to northern Colombia.

🌳 One interesting function of the cardinal flower in ecosystems is serving as a vital nectar source for hummingbirds. The tube-shaped flowers are specifically adapted to fit the long beaks of hummingbirds, making the cardinal flower an evolutionary partner in the birds’ quest for nectar. Consequently, the cardinal flower not only aids in its own pollination but also helps sustain the local hummingbird population, which has both ecological and horticultural value.

🎭 Difference

Care Guide

💧 Water Every week

The cardinal flower flourishes in moist environments and consistently needs water. Although it can tolerate moderate drought, watering it weekly encourages lush growth. As an herbaceous perennial, it benefits from natural rainfall, which enhances its water cycle and supports vibrant blooms during the growing season.

Suggested frequency: Every week
FAQ
How should I water my Cardinal flower?

When watering the Cardinal flower, it is best to use filtered water at room temperature or slightly warmer. Tap water may contain harmful particles for the plant's health. Since the Cardinal flower comes from a warm environment, it is important to avoid using cold water to prevent shocking its system. It is also recommended to avoid overhead watering as it can lead to foliage complications. Instead, apply filtered room temperature water directly to the soil until it is completely soaked. This assists in moisturizing the roots and allowing them to spread through the soil and absorb necessary nutrients.

What do I do if I give my Cardinal flower too much or too little water?

Both overwatering and underwatering can harm your Cardinal flower's health, but overwatering is more commonly problematic. Too much water can cause the stems and leaves to wilt and turn yellow. Prolonged overwatering can also lead to diseases like root rot, mold, and mildew, which can kill the plant. While underwatering is less common, it is still possible for the Cardinal flower. In such cases, the leaves may become brittle and brown. It is important to quickly identify signs of overwatering when caring for your Cardinal flower. Some diseases caused by overwatering, such as root rot, may not be reversible if you delay action. If you observe early signs of overwatering, reduce your watering schedule immediately. Additionally, check the soil quality where your Cardinal flower is growing. If the soil drains poorly, replace it with a loose, well-draining potting mix. Conversely, if you notice signs of insufficient watering, simply water more regularly until the signs improve.

How much should I water my Cardinal flower?

If your Cardinal flower is in a pot, the best way to check if it needs water is by putting your finger in the soil. If the top two to three inches of soil are dry, then it's time to water the plant. If your Cardinal flower is planted in the ground, you can use the same method to check the soil. When the top few inches of soil have dried out, it's time to water it. Normally, you would water it about once a week in spring and early fall. In very hot weather, you may need to water it twice a week or even more. However, keep in mind that mature Cardinal flowers that are well-established can tolerate drought quite well.

How much water does my Cardinal flower require?

To properly water your Cardinal flower, don't hold back on the amount of water you give. Make sure the top two to three inches of soil are dry before watering. Give it a good, deep watering that completely soaks the soil. Add enough water to allow excess water to drain out of the pot's bottom drainage holes. If you don't see any excess water draining, you probably didn't give it enough water. However, be careful not to let water accumulate in the soil, as that can harm the plant. On the other hand, if water isn't draining properly, it could mean you have poorly draining soil, which is not good for the plant's health. If the plant is outside, it should receive about 1 inch of rain per week.

How do I water my Cardinal flower as it grows?

The water needs of the Cardinal flower can vary depending on its growth stages. When the plant is in its early years or has been recently transplanted, it requires more water than usual. During these stages, the Cardinal flower directs a lot of energy towards developing new roots, which need extra moisture to support future growth. Once the plant has matured after a few seasons, it will require less water. Additionally, during the bloom period, the Cardinal flower may need increased watering as flower development requires a significant amount of moisture.

☀️ Light Full sun

Cardinal flower does best when exposed to a full day's light, though it can tolerate some periods of reduced illumination. It originates from open woodland, reflecting its preference for abundant light. While it can survive under weaker light, its best health and growth occur with strong light. However, excessive light exposure can produce negative effects.

Ideal: Full sun
FAQ
What are the sunlight requirements for a Cardinal flower?

The Cardinal flower, or Lobelia cardinalis, thrives under various light conditions but shows optimal growth with ample sunlight. It requires full sun, meaning above 6 hours of sunlight daily, but can also grow under partial sun, which is about 3-6 hours of sunlight. The plant's native environment being open woodlands, indicates its preference for significant light exposure, though it can manage with less. It's essential to observe the movement of sunlight in your garden to choose the best spot for your plants, providing them with the ideal balance of light and shade.

How does artificial lighting affect the growth of indoor Cardinal flowers?

Indoor Cardinal flowers may require artificial lighting to supplement natural sunlight, especially in spaces with limited light exposure or during less sunny seasons like winter. Adequate lighting is crucial for optimal growth. LED lights are a popular choice, as they can be customized to provide specific wavelengths needed by the plants. Full sun plants need 30-50W/sq ft, partial sun plants 20-30W/sq ft, and full shade plants 10-20W/sq ft of artificial light. The light source should be placed 12-36 inches above the plant for 8-12 hours per day to mimic natural sunlight.

What are the signs of inadequate lighting for a Cardinal flower?

Signs of inadequate lighting in Cardinal flowers include smaller new leaves, leggy or sparse growth, faster leaf drop, slower or halted growth, lighter-colored new leaves, chlorosis, sunscald, leaf curling, wilting, and leaf scorching. These symptoms indicate that the plant is not receiving enough light, leading to poor health and growth. Conversely, chlorosis and sunscald can occur from too much direct sunlight. Observing these signs can guide adjustments in the plant's exposure to light for better health.

What solutions can be applied to address lighting issues for Cardinal flowers?

To address lighting issues for Cardinal flowers, gradual adjustments to light exposure are recommended. For indoor plants, move them to a sunnier location each week until they receive at least 6 hours of direct sunlight daily, utilizing south-facing windows and keeping curtains open. If the plant is large or hard to move, consider using artificial light sources for at least 8 hours daily. Outdoors, adjust plants gradually to sunnier spots to prevent sunburn. Removing obstacles that block sunlight and transplanting smaller plants to brighter locations can also help. It's important to note that parts of the plant affected by lack of light may not recover, but increased light exposure can ensure new growth is healthy.

🌡️ Temperature 0–35°C

The cardinal flower naturally grows near water in temperate regions and favors temperatures of 32 to 95 ℉ (0 to 35 ℃). In summer, the plant may benefit from a slight drop in temperature or from being shaded from intense sun. In winter, it can tolerate freezing temperatures but might need protection during particularly severe cold snaps.

Ideal temperature: 0–35°C
FAQ
What is the native growth environment of the cardinal flower?

The cardinal flower, Lobelia cardinalis, flourishes in environments close to water sources within temperate regions. It prefers temperatures ranging from 32 to 95°F (0 to 35°C). During the hot summer months, the plant may benefit from a slight decrease in temperature or some shading from the intense sun. Conversely, in winter, while the cardinal flower shows strong cold resistance and generally does not need special frost protection measures, it can adapt to freezing temperatures. However, in the case of severe cold snaps where temperatures are expected to drop significantly, it's important to provide additional protection by covering the plant with insulating materials like soil or straw. Furthermore, watering the plant abundantly before the first freeze of autumn is recommended to ensure that the soil remains moist and enters the frozen state, which helps prevent drought and water scarcity during the winter and early spring.

How does the cardinal flower respond to low temperatures?

The cardinal flower is notably cold-tolerant and thrives best when the temperature is maintained above its specified minimum acceptable level. During the winter months, it's crucial to keep the plant above this minimum threshold to avoid negative impacts. If temperatures drop below a critical limit, though there might not be any noticeable changes in the plant during the winter, it could result in decreased sprouting or potentially no sprouting at all come springtime. In response to such occurrences, removing any parts that have failed to sprout during spring is advised as a remedial action.

What should be done if the cardinal flower experiences high temperatures?

During the summer, it is important to ensure that the cardinal flower is kept below its maximum temperature tolerance. Exceeding this temperature can lead to the plant's leaves becoming lighter in color, curling, becoming susceptible to sunburn, or, in severe cases, causing the entire plant to wilt and dry out. To mitigate these effects, any sunburned or dried-up parts of the plant should be trimmed away. Moving the plant to a location that provides shade during the midday and afternoon sun, or using a shade cloth, can help protect the plant from excessive heat. Additionally, watering the plant in the morning and evening to maintain soil moisture can be beneficial in keeping the plant healthy under high temperature conditions.

💨 Humidity normal (40-60%)

This plant will thrive in moderate humidity, which is probably the level in your home. However, misting it a few times a week can be very beneficial. Make sure the room has good ventilation.

Humidity: normal (40-60%)
🪴 Soil 6-7
Soil pH: 6-7
🌱 Fertilizer

The best time to fertilize a Cardinal flower is in early spring, as it comes out of dormancy and begins active growth. Fertilizing supplies essential nutrients for healthy development. Although the Cardinal flower has relatively low fertilizer requirements, giving it fertilizer once a year can improve its survival and encourage better, longer-lasting blooms.

FAQ
What will happen if I give my Cardinal flower too much fertilizer?

When caring for your Cardinal flower, remember that it doesn't require much fertilizer and can suffer if it receives too much. Overfertilizing can lead to fertilizer burn, where excessive fertilizer draws nutrients and moisture away from the roots, causing the plant to decline. It can also weaken the plant and make it more susceptible to disease. Overfertilization may result in fewer or no flowers, which is a significant disadvantage since the blooms are highly valued by gardeners.

Why should I put plant food on my Cardinal flower?

Fertilization is important for the Cardinal flower for a few reasons. It provides essential nutrients for the plant's growth both above and below the surface. While the Cardinal flower's fertilization requirements are generally minimal, periodic fertilization can benefit the plant, promoting its survival and enhancing the blooming period of its flowers. For optimal growth and appearance, regular annual fertilization is recommended.

What is the ideal time to fertilize my Cardinal flower plant?

The best time to fertilize a Cardinal flower is in late winter to early spring. This is when the plant transitions from dormancy to active growth, and fertilizing at this time promotes healthy growth for the season. While it's typically best to fertilize in early spring, fall is also acceptable. However, it's not recommended to fertilize in summer or winter.

When is the best time to not add fertilizer to my Cardinal flower?

To properly care for your Cardinal flower, it is best to fertilize it only during late winter and early spring. This plant has low fertilization needs, so a single annual feeding should suffice. Overfertilizing during spring, summer, and fall can cause complications, so it is important to avoid it. However, if you missed fertilizing in spring, it is acceptable to feed the plant in fall. Additionally, there is no need to fertilize the Cardinal flower in winter. During this time, the plant goes into a dormant growth phase and does not put forth new growth, making fertilization not recommended.

What kind of fertilizer does my Cardinal flower require?

To help your Cardinal flower thrive, you have a few options for fertilizers. A general-purpose fertilizer that has a balanced amount of the three main plant nutrients will work well. However, some specific nutrient blends can be even more beneficial. For example, many gardeners believe that higher levels of phosphorus support stronger roots and better flowers. Since the Cardinal flower is a flowering plant, using a fertilizer with more phosphorus may be the best choice. You can use either granular or liquid fertilizer, as long as it contains adequate nutrients. Apart from manufactured fertilizers, you can also improve the soil for your Cardinal flower using organic methods. Compost, manure, and similar materials can greatly enhance the growing medium and promote its healthiness.

🪴 Pot & Repot 2-3 years

When repotting Cardinal flower, select a pot 1-2 inches (2.5–5.1 cm) larger with good drainage. Use a well-draining potting mix. Repot in spring or fall, making sure the root ball is slightly lower than the rim of the flower pot. Water thoroughly after repotting and place in a warm spot with indirect sunlight.

Suggested frequency: 2-3 years
✂️ Pruning

Prune cardinal flowers from early to late spring to promote healthy growth and remove any dead stems. After the plant has finished flowering, cut it back to the base. This prepares the plant for the next season and prevents it from self-seeding. Regular pruning also improves air circulation and reduces the risk of disease, supporting vigorous flowering.

🌿 Propagating
🐛 Diseases & pets
☠️ Toxicity

Characteristics

Plant Type
Herb
Life Cycle
Perennial
Genus
Lobelia
Family
Campanulaceae
Hardiness Zone
3-9
Mature Height
0.61 m to 1.52 m
Mature Spread
30 cm to 61 cm
Leaf Color
Green, Red
Leaf Type
Deciduous
Flower Color
Red
Flower Size
2.54 cm to 7.62 cm
Bloom Time
Mid summer
Planting Time
Spring
Harvest Time
Mid summer
Native Area
Colombia, Belize, Honduras, Mexico, Guatemala, Nicaragua, Costa Rica, Panama

Tags (28)

Common Names (7)

ar زهرا
en Cardinal Flower
en Scarlet lobelia
en Red Cardinal Flower
en Cardinal Lobelia
en Lobélie du Cardinal (FR)
en Kardinals-Lobelie (DE)