|How to grow Oxalis versicolor from seed|
Commonly known as the Candy Cane Sorrel, Oxalis versicolor is a bulbous perennial native to South Africa. The species name versicolor means 'changing colour', referring to the eye-catching red and white flowers.
It is a clump forming species which under favourable can be expected to grow to approximately 8 cm height. The light green leaves are composed of three narrow leaflets. Appearing from late summer into winter the funnel-shaped, each white petal is margined with a crimson vertical stripe underneath. This provides an unusual yet attractive candy-stripe effect while in bud, hence the common name.
Due to its warm-temperate to subtropical origins, Oxalis versicolor can only be considered half-hardy in the cooler temperate conditions of northern Europe.
Plant outside in a sheltered position in either full sun or partial shade. Alternatively grow under the protection of an alpine house in bright filtered light. It will perform best when grown in a well-drained sandy loam.
Growing Oxalis versicolor from seed
In northern Europe Oxalis versicolor seeds will need to be sown in a modular seed tray under protection in the spring. Sow the seeds onto the surface about 1mm deep in a well-drained soil-based seed compost such as John Innes compost or make your own mix from equal parts loam, leaf mould and grit. Press the seeds into the compost buy do not bury and then cover with a very light covering of compost, horticultural grit or vermiculite.
Gently water in, but not too much water and the leave in a heated propagator with the vents closed with temperatures between 15ºC to 21ºC during the day and 13ºC to 18ºC at night. Germination will take approximately 14-60 days. Once the first seedlings start to emerge increase ventilation. Each seeding can be potted on into a 9cm pot once its roots have established in the module. Take care not to disturb the root system while completing this action.
Water moderately when in growth and apply a balanced liquid fertiliser monthly. Avoid waterlogged soils and only water once the top 5 cm of soil has dried out. Keep barely moist when dormant over the winter and do not fertilize as this can cause the bulbs to soften and rot.
Once the threat of late frosts has passed, harden the young plants to outdoor conditions for 10-14 days before planting outside into their final position.
Protect seedlings from damage from slugs and snails.
Main image credit -NZ Fauna https://creativecommons.org/licenses/by-sa/3.0/deed.en