Grewia occidentalis

Growing Guide: How to Care for Grewia occidentalis and Encourage Abundant Flowering

This exotic, purple-flowering bonsai is one of the most rewarding indoor bonsai plants. Although it originates from warm subtropical regions, it adapts surprisingly well to indoor cultivation. If you provide it with plenty of light, balanced watering, and high-quality nutrients, it will reward you with vigorous growth, rapid trunk thickening, and regular production of new buds.

Location, Light, and Careful Watering

For the Lavender Star to bloom profusely, it needs as much sunlight as possible. The ideal location is a very bright windowsill facing south, east, or west. A lack of light causes the branches to stretch and significantly reduces flower production. During the summer months, it is extremely beneficial for the Star of Bethlehem to be placed outdoors in the garden or on a balcony in full sun.

Adjust watering according to the season and light intensity. Keep the soil slightly moist, but never allow the tree to stand in waterlogged soil for extended periods, as this could damage the root system. Water generously when the soil surface begins to lighten slightly. During the winter, when the apartment is heated, Grewia occidentalis will appreciate occasional misting of the crown.

Substrate, Repotting, and Fertilization for Flowering

For proper root system development and protection against rot, Grewia bonsai require a highly permeable growing medium:

• Substrate: We recommend using our specially blended soil and bonsai substrates. For routine repotting, the ready-to-use universal Bonsai Master 2-liter mix is ideal. For larger trees and more demanding growers, the Bonsai Master AK mineral substrate (3–3.7 mm), 14 liters, based on Japanese Akadama, is an excellent choice, as it ensures a constant supply of oxygen to the roots.
• Repotting: We usually repot young trees after 1–2 years, ideally at the start of active growth or after flowering, always depending on the condition of the roots and how quickly the substrate dries out, while trimming the root ball appropriately by about one-quarter.
• Fertilization: Flowering bonsai have high nutrient requirements. From spring through fall, apply high-quality bonsai fertilizer every 14 days (during bud set, choose fertilizers with higher phosphorus and potassium content to promote flowering). In winter, fertilize once a month.

Frequently Asked Questions About Lavender Star (FAQ)

How do you prune and shape the Lavender Star?

Shaping Grewia occidentalis is relatively simple, and it tolerates pruning very well. We shorten new shoots with pruning shears just past the second or third pair of leaves, after the internodes have lengthened slightly. However, if you want to achieve an abundance of flowers, let the twigs grow slightly in the spring, as buds form on new growth. To shape the plant into the desired style (most commonly the loosely upright Moyogi style), you can use aluminum wire to gently wire the semi-woody branches.

Why isn’t my Lavender Star blooming or is it dropping its buds?

The most common cause of a lack of flowers is a lack of direct sunlight or irregular fertilization with a low phosphorus content. If buds form but fall off before blooming, the culprit is usually sharp fluctuations in substrate moisture (the root ball drying out followed by sudden overwatering) or an icy draft from ventilation during the winter months.

How to overwinter the Lavender Star in an apartment?

Since this is a heat-loving indoor bonsai, the temperature in its location should not drop below 12 °C for extended periods during the winter (the ideal winter temperature is 15–20 °C). Place it by the brightest window possible. As the heating season begins, slightly reduce watering depending on the room temperature, but never let the potting mix dry out completely.