Oxalis Triangularis is one of the most sought-after houseplants. Whether lime green (called Oxalis Regnelli), bicolor, deep purple or some shade in between (like Oxalis Sanne), lucky shamrocks make the perfect addition to any environment. Plus, they are very easy to grow!
Oxalis bulbs, also known as wood sorrels or shamrocks, are loved by gardeners for their cheery flowers and vivid foliage. Many people wonder when the best time is to plant these pleasant bulbs for optimal growth and blooms. The ideal planting time depends on several factors, including your USDA hardiness zone, the specific oxalis variety, and whether you intend to grow them indoors or outdoors.
How Do Oxalis Bulbs Grow?
Oxalis bulbs are unique because they have an opposite growth pattern from many other bulbs. While most bulbs grow actively in spring and summer and go dormant in winter, oxalis bulbs flourish in cooler weather and go dormant in summer heat. They behave more like an herbaceous perennial than a true bulb.
During their active growth in spring and fall, lush clover-like foliage emerges, followed by dainty flowers in shades of white, pink, yellow, or purple. The flowers usually have 5 petals and bloom open during the day and closed at night. When temperatures climb in early summer, the foliage dies back and the plant goes dormant until cooler weather returns.
Best Time to Plant Oxalis Outdoors
Most oxalis varieties thrive when planted outdoors in early spring, just before the last expected frost date in your area This gives them a chance to establish roots before summer dormancy hits Some gardeners also have success planting oxalis bulbs in fall, 6 to 8 weeks before the first frost date. Fall planting allows time for good root growth before winter dormancy.
Ideal outdoor planting times
- Spring – 6 to 8 weeks before last frost date
- Fall – 6 to 8 weeks before first frost date
If you live in zones 8 to 10 where winters are mild, you can plant oxalis anytime during the cool weather months for extended bloom seasons.
Best Time to Plant Oxalis Indoors
When growing oxalis as houseplants, timing isn’t as strict They can be planted anytime you want cheerful blooms to brighten your indoor space
Most gardeners recommend planting oxalis bulbs indoors around 6 to 8 weeks before you want them to bloom. This gives adequate time for root establishment and top growth to emerge before flowers arrive.
Indoors, oxalis can bloom year-round if given sufficient bright, indirect light. Move them outside in summer if temperatures exceed 80°F, which can induce dormancy. After a dormant period over summer, bring bulbs back inside in fall and water to restart growth.
Tips for Planting Oxalis Bulbs
Follow these tips to get your oxalis bulbs off to the right start:
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Soak bulbs in water overnight before planting to hydrate them.
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Plant bulbs pointed-side up and spaced 2 to 4 inches apart. Outdoor planting depth is 2 to 3 inches. Indoors, cover bulbs with 1 to 2 inches of soil.
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Use well-drained soil enriched with compost or organic matter.
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Water lightly after planting and whenever the top inch of soil is dry. Avoid overwatering.
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Give bulbs at least 4 hours of direct sunlight daily for best blooms. Provide some afternoon shade in hot climates.
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Fertilize monthly with a balanced liquid fertilizer while bulbs are actively growing.
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Stop fertilizing and reduce watering during summer dormancy to avoid rot.
Ideal Varieties for Indoor and Outdoor Growing
With over 500 oxalis species, there are many options to choose from. Here are a few top varieties for indoor and outdoor growing:
Outdoor Varieties
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Oxalis ‘Ione Hecker’ – Lavender-pink flowers on green foliage
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Oxalis luteola – Yellow flowers on clover-like leaves
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Oxalis tropaeoloides – Deep bronze foliage with yellow blooms
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Oxalis regnellii ‘Atropurpurea’ – Deep burgundy foliage with lavender flowers
Indoor Varieties
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Oxalis triangularis – Purple shamrock foliage with pink or white flowers
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Oxalis tetraphylla ‘Iron Cross’ – Deep green clover leaves with iron cross markings
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Oxalis purpurea ‘Alba’ – White flowers over purple-red leaves
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Oxalis massoniana – Lime green and cream variegated leaves with white or pink flowers
The ideal oxalis bulb planting time ranges from early spring to early fall, depending on your climate and whether you are growing them indoors or outside. Soak bulbs before planting, use well-drained soil, provide bright light, and water moderately for the best results. With their cheerful blooms and fascinating foliage, oxalis bulbs are one of the easiest and most rewarding bulbs to grow in any garden.
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As theyre easy growers both in-ground and in containers, feel free to use this plentiful plant for edging, container gardens, or as indoor windowsill accents. Oxalis love sunlight but appreciate some protection during the hottest part of the day. For example, south-facing windows are perfect for winter but may be too hot during the summer. In USDA zones 6 through 10, it can grow outdoors in borders or edgings but should be treated as a houseplant in cold winter areas.
Oxalis go dormant in the summer rather than the winter and prefer being planted in the spring, as this lines up with their regular blooming period. Many species flower sometime between spring and summer with possible repeat blooms in the fall. While foliage typically emerges 3–4 weeks after planting, flowers can take 8–10 weeks to arrive.
- For outdoor landscape planting, locate an area with well-drained soil where your Oxalis will receive plenty of sunlight. If you live in a warmer climate, be sure to provide some afternoon shade. Dig holes large enough to house your Oxalis bulbs and position them approximately 3–4 inches apart and at a depth of 1–1 ½ inches. After placing the bulbs in the holes, cover with the surrounding soil and gently tamp down.
- For container planting, find an area in your home with bright direct light and fill your container about three-quarters full with a well-drained potting mix. Water to settle the soil before placing the bulbs on top, spacing them several inches apart. Cover the bulbs with 1–2 inches of additional soil. If your Oxalis arrived pre-planted, feel free to skip this step and use the shipped container.
- Water lightly, ½ to 1 cup will usually do the trick until top growth emerges.
- Water lightly during active growth about once per week when the top half of the soil feels dry.
- Fertilize your Oxalis lightly with a diluted liquid fertilizer once every month while the plant is actively growing.
- Prune away dead foliage in late summer as the plant begins to die and slip into dormancy.
- Stop watering and fertilizing while your plant rests in its dormancy period.
- Resume watering and fertilizing once your Oxalis begins to regrow in the spring.
How to care for Oxalis triangularis – the basics
Your oxalis will bloom from spring until the first frost with little light pink flowers. Heres an overview of false shamrock care:
- Water: Water every 1-2 weeks, when the top 2 centimeters (1 inch) of soil becomes dry. Make sure your pot has drainage holes. Expect to water more often in brighter light and less often in lower light.
- Light: Thrives in bright indirect to bright direct light.
- Humidity: Any humidity level will do. Normal room humidity is fine.
- Temperature: Best not to let it go below 60°F (15°C).
- Fertilize: Once a month during the growing season using a slow-release blend.
- Pruning: Simply pinch off any dead or discolored foliage.
- Propagation: To propagate oxalis, wait until the following season to separate the rhizomes.
How To Plant Oxalis Bulbs In Just 2 Minutes
FAQ
Where is the best place to plant Oxalis?
- Light: Oxalis prefers bright, indirect light but can tolerate some direct sunlight, especially in the morning or late afternoon. Avoid placing them in direct sunlight for extended periods, as this can scorch their leaves.
- Soil: They need well-drained soil that is slightly acidic to neutral. If you have heavy clay soil, you may need to amend it with compost or organic matter to improve drainage.
- Location:
- Outdoor: Choose a spot in full sun to partial shade, especially in hot climates.
- Indoor: Place them near a bright window with filtered light or use grow lights to supplement natural light.
- Outdoor: Choose a spot in full sun to partial shade, especially in hot climates.
- Climate: Oxalis are generally cool-season plants and prefer temperatures around 60°F. They may not tolerate freezing temperatures, so they may need to be brought indoors or treated as annuals in colder climates.
- Watering: Keep the soil moist but not soggy, especially during the growing season.
- Dormancy: Oxalis plants will go dormant during the winter months and can be placed in a cool, dark room.
- Spacing: In the garden, space plants 3-4 inches apart and 1-1 1/2 inches deep.
- Container Planting: Use a well-draining potting mix and plant bulbs about an inch deep.
- Forcing Bulbs: You can force oxalis bulbs indoors before planting them outdoors by placing them in a bright, cool location.
Do Oxalis come back every year?
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Dormancy:Oxalis plants, especially those grown from bulbs or tubers, require a period of dormancy each year. This dormancy is a natural part of their lifecycle and allows them to store energy for the next growing season.
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Foliage Die-back:During dormancy, the leaves of Oxalis plants may die back, and the plant may appear to be dying.
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Reemergence:With proper care, including reducing watering during dormancy and providing bright, indirect light and moderate watering when they emerge, the plant will come back better than ever.
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Perennial Nature:Many species of Oxalis are perennials, meaning they live for more than two years. This means that with proper care, they can grow back and bloom year after year.
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Annual vs. Houseplant:Some Oxalis species, like Oxalis triangularis, can be grown either as an annual or a houseplant. If grown in the ground in a colder climate, the tubers can be lifted and stored during the winter to be replanted in the spring.
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Houseplant Care:If growing Oxalis as a houseplant, you can let it go dormant in the winter by reducing watering and placing it in a cool, dark spot. In the spring, you can bring it back to a bright, indirect light location and resume watering.
Do Oxalis bulbs multiply?
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Natural Multiplication:Oxalis plants naturally produce new bulbs or corms (the underground storage structures) from the main plant. These new bulbs can then develop into separate plants.
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Propagation by Division:Due to this natural multiplication, Oxalis are very easy to propagate by dividing the plant. You can simply take the mature plant out of the soil, gently separate the bulbs or corms, and plant each one in its own pot or spot.
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Rapid Growth:Oxalis bulbs tend to multiply quickly, making them an easy plant to propagate and spread.
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Easy to Manage:If the plant becomes too large or overcrowded, you can easily divide it and create multiple plants.