Sophora microphylla — an easy houseplant, prefers full sun light
SPECIMEN · FROM THE LIBRARY
Sophora microphylla

Sophora Microphylla

Updated · 123 observations
ON THIS PLANT

Sophora microphylla, common name kōwhai, is a species of flowering plant in the family Fabaceae, native to New Zealand. Growing to 8 m (26 ft) tall and broad, it is an evergreen shrub or small tree. Each leaf is 10 cm (4 in) long with up to 40 pairs of shiny oval leaflets. In early spring it produces many racemes of pea-like yellow flowers.Other common names include weeping kōwhai and small-leaved kōwhai. It is also referred to as South Island Kowhai although this name is misleading since it is widely distributed all over New Zealand including the North Island, though less common in Northland. The specific epithet microphylla means "small-leaved". S. microphylla has smaller leaves (around 3–6 mm long by 2–5 mm wide) and flowers (1.8-5.0 cm long), than the other well known species Sophora tetraptera (large-leaved kōwhai). When young S. microphylla has a divaricating and bushy growth habit with many interlacing branches, which begins to disappear as the tree ages.The cultivar Sun King 'Hilsop' has gained the Royal Horticultural Society's Award of Garden Merit.Its nectar is toxic to the honeybee.

A note from PlantMom

Kōwhai is resistant to disease and is usually not susceptible to illnesses. Regarding upkeep, this plant is fairly low maintenance. When grown outdoors it needs little watering, and larger plants usually do not need pruning. Smaller plants, however, should be pruned after they have finished blooming. Kōwhait is suitable for anyone with an outdoor area, such as a garden or deck, and does not require much care experience.

— PlantMom
CARE GUIDE

How to keep Sophora Microphylla.

Light

Kōwhai grows best with plentiful light, reflecting its natural habitat. Increased sun exposure encourages more vigorous, healthy growth. By contrast, insufficient light can impair its development and overall wellbeing.

Water

Kōwhai thrives in drier conditions and is drought-tolerant, requiring water only every two weeks. It is mainly grown outdoors, where it can benefit from natural rainfall. Being a deciduous plant, kōwhai needs less water during its dormant period, helping it conserve resources for the growing season.

Temperature

Kōwhai originates from temperate regions and does best in temperatures ranging from 68 to 100 °F (20 to 38 ℃). As the four distinct seasons draw near, it's advisable to slowly acclimate the plant to the changing temperatures.

Fertilizer

The best time to fertilize a Kōwhai is in early spring as it breaks dormancy. This encourages overall growth and flower development. Applying fertilizer improves foliage, stems, and branches, and supports large, vibrant, long-lasting blooms. It helps transport nutrients from the roots to the flowers and enhances the plant’s health and resistance to disease.

Pruning

Kōwhai, which boasts vibrant yellow flowers, benefits from pruning between early and late winter. Focus on removing dead wood and thinning out dense areas to improve airflow. Regular, light trimming encourages more blooms and reduces the risk of disease, promoting a healthy and attractive plant.

CHARACTERISTICS

Botanical profile.

Plant Type
Tree, Shrub
Life Cycle
Perennial
Genus
Sophora
Family
Fabaceae
Hardiness Zone
9-11
Mature Height
3.05 m
Mature Spread
3.05 m
Leaf Color
Green
Leaf Type
Evergreen
Flower Color
Yellow
Flower Size
2.54 cm
Bloom Time
Late winter, Early spring, Mid spring
Planting Time
Spring
Harvest Time
Late spring, Early summer, Mid summer
Native Area
New Zealand
ALSO KNOWN AS

Other names.

en Kowhai
FREQUENTLY ASKED

Reader questions.

How should I water my Kōwhai plant?

Your Kōwhai is not particularly fussy about how you water it. You can use any common watering tool - like a watering can, hose, or even a cup - to dampen its soil. Regardless of what tool you choose, it's important to apply the water directly to the soil and make sure all areas are evenly moistened to provide water to all parts of the root system. Using filtered water is helpful, as tap water can contain harmful particles. It's also better to use water at room temperature or slightly above, as extreme temperatures can be a bit jarring for the Kōwhai. However, the Kōwhai generally responds well to any type of water you provide.

Why should I use fertilizer for my Kōwhai plant?

Fertilization is crucial for the overall health of a Kōwhai. By providing the necessary energy and nutrients, proper fertilization promotes the growth of healthy foliage and strong stems and branches. Additionally, gardeners highly value the flowers of a Kōwhai, and fertilization benefits them too. With the right fertilizer, the plant produces large, vibrant, and long-lasting flowers. This happens because the appropriate fertilizer facilitates the transfer of fuel from the roots to the flowers through the stems. Moreover, adequate fertilization contributes to the plant's overall health, strengthening its ability to fend off diseases.

What are the sun requirements for Kōwhai?

Kōwhai requires full sun, defined as more than 6 hours of sunlight daily, but it can also tolerate partial sun, which means about 3-6 hours of sunlight. It's important to observe how sunlight moves through your garden to find spots that offer the right balance of light and shade, ensuring your plants thrive.

What are the ideal temperature conditions for Kōwhai?

Kōwhai thrives in temperate climates, ideally with temperatures ranging from 68 to 100 °F (20 to 38 °C). It is extremely heat-loving and not tolerant of cold temperatures. As the seasons change, it's important to gradually acclimate Kōwhai to the changing temperatures. During winter, maintaining temperatures above 20°C and avoiding any exposure to temperatures approaching 0°C are crucial for the plant's health.

What do I need to do if I give my Kōwhai too much or too little water?

When it comes to outdoor plants, especially newly planted ones or seedlings, they are prone to not getting enough water. It's important to remember to water them regularly for a few months while they are still small or newly planted. Once the roots are established, Kōwhai plants can rely on rain most of the time. However, when Kōwhai plants are in pots, overwatering is more likely to happen. If you accidentally overwater your Kōwhai, there are steps you can take to fix it. First, stop watering the plant immediately to minimize the impact of overwatering. Then, remove the Kōwhai from its pot to check the roots. If the roots don't show any signs of root rot, you can put the plant back in its container. But if there are signs of root rot, trim the affected roots and consider applying a fungicide to prevent further damage. Finally, repot the Kōwhai in well-draining soil. On the other hand, if your Kōwhai is underwatered, the solution is simple. Just water the plant more frequently. When a Kōwhai plant is underwatered, its leaves may droop, dry out, and fall off. However, they will quickly regain their fullness after sufficient watering. Make sure to adjust your watering frequency as soon as you notice your Kōwhai is underwatered.

When should I fertilize my Kōwhai plant?

Fertilizing a Kōwhai is most effective in early spring when the plant is exiting dormant phase and preparing for bud opening. This provides ample energy for growth and flower development. However, it's not the only suitable time for feeding. Another feeding in the fall can benefit the plant, though it doesn't have to be as large as the first. Some gardeners prefer to fertilize during planting, but it's not always necessary.

Why is light essential for Kōwhai's growth?

Light is crucial for Kōwhai's growth, mirroring its natural habitat's conditions. Adequate sunlight exposure encourages healthy growth, while insufficient light may impede the plant's development and health. For indoor Kōwhai or in scenarios where natural light is lacking, especially during winter or in dimmer spaces, artificial lighting becomes essential for maintaining optimal growth.

How should I care for Kōwhai during winter?

In the autumn, as temperatures start to drop, it's recommended to bring outdoor-grown Kōwhai indoors and place it near a bright window, ensuring it's not too close to heaters. This helps to maintain an optimal growth temperature above 20°C and protects the plant from cold damage. Ensuring the plant is not exposed to freezing temperatures is critical for its survival during the colder months.

How often should I give water to my Kōwhai plant?

If your area doesn't get much rainfall, you may need to water your outdoor plants every 2 weeks in the spring and fall, and more often in the summer. In the winter, you may not need to water at all since the plants grow slower and require less water. However, if you have a young or newly planted Kōwhai, you should water more frequently to help it establish and grow. For potted plants, you have two options for determining watering frequency. One is to follow a set schedule, either weekly or every other week, but this may not always be suitable for your Kōwhai's specific conditions. The other option is to check the soil moisture and wait until the top two to four inches have dried out before watering again. This method may be more effective, especially during the summer when the plant needs more water.

When is it not a good idea to add fertilizer to my Kōwhai plant?

During the winter, Kōwhai plants are in a dormant phase and do not require fertilization like other plants. They do not need much energy from the soil to grow during this time. Fertilizing them in winter can lead to overfertilization and its negative effects. The optimal feeding times for Kōwhai plants are early spring and fall. Therefore, during most of spring and summer, they do not need fertilizer. Additionally, it is advisable to abstain from feeding if the plant is exposed to excessively hot or dry conditions.

How can artificial lighting support plant growth?

Indoor plants, including Kōwhai, demand adequate lighting for optimal growth. When natural sunlight is insufficient, artificial lights offer a vital alternative. LED lights are preferred for their ability to provide specific light wavelengths needed by plants. Full sun plants require 30-50W/sq ft, partial sun plants need 20-30W/sq ft, and full shade plants need 10-20W/sq ft of artificial light. The light source should be placed 12-36 inches above the plant, mimicking natural sunlight, and most plants will need 8-12 hours of light per day.

What should I do if Kōwhai is exposed to low temperatures?

If Kōwhai is exposed to low temperatures, especially below -5°C, and shows signs of frost damage such as leaves lightening in color or turning brown or black, immediate action is required. Trim off the frost-damaged parts and move the plant indoors to a warm environment, preferably near a south-facing window for ample sunlight. Avoid placing the plant near heaters or air conditioning vents to prevent air dryness.

PLATES
Sophora microphylla leaf
PLATE 01 · leaf
Sophora microphylla leaf
PLATE 02 · leaf
Sophora microphylla flower
PLATE 03 · flower
Sophora microphylla flower
PLATE 04 · flower
Sophora microphylla fruit
PLATE 05 · fruit
Sophora microphylla fruit
PLATE 06 · fruit
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