Hibiscus
A hibiscus with a dual purpose: ornamental during the autumn flowering and valuable in the kitchen for its red, fleshy calyces.
About the variety. This variety produces bell-shaped flowers in light pink that bloom as the days shorten. It is the succulent calyces, harvested 7–10 days after petal drop, that have culinary use. A tall-growing plant, reaching 150–200 cm; greenhouse cultivation is recommended in cold regions.
Itinerário técnico
Um guia de cultivo passo a passo, da sementeira à colheita.
Sow in trays six to eight weeks before planting out, one centimetre deep, at 24 °C to 28 °C. The coat is hard: soak the seed for twelve hours or nick it lightly with sandpaper before sowing. Germination takes seven to fourteen days. Plant out after the last frosts with plenty of room, because the shrub reaches two metres. Plant fifty centimetres apart in the row with a metre between rows: the shrub is stout, stands on its own and needs no stake.
It wants loose, fertile and free draining soil at a pH between 5.5 and 7.0. It is not very demanding, but appreciates mature compost in the planting hole. It does not tolerate waterlogged ground. In heavy soil plant on a ridge or raised bed; in a container use at least thirty litres of compost per plant.
It needs strong heat and a long season, between 22 °C and 32 °C, and is very frost sensitive. Flowering is triggered by short days, which means it only flowers in late summer and autumn: where cold arrives early, the flowers never get to form calyces. In that case grow it under glass or in a pot that can be brought in. In Italy it is an easy crop: in the centre and south plant from April onwards and the only real care is light shade through the July and August heat; in the Po valley and the north wait for the late frosts to pass and pick the sunniest spot you have. Inland in Portugal and Spain and in southern France it finishes without difficulty, but on the cool Atlantic coast, in northern France and in Germany it only gets there if started early with bottom heat and grown in a greenhouse, a tunnel or against a south facing wall.
Its needs are moderate. One to two kilos of mature compost per square metre worked in before sowing covers most of the cycle. If the leaves pale, one watering with a balanced liquid organic feed halfway through is enough. Never use fresh manure, which burns roots and encourages disease.
Water regularly during growth without waterlogging. Once established it tolerates dry spells well. Reduce watering while the calyces form, to concentrate the flavour.
Hand weed in the first weeks, while the plant is small and loses every contest for light and water. Once it is established, mulch with five to seven centimetres of straw, dried grass or leaves: it holds weeds back, keeps moisture in and stops rain splashing soil onto the lower leaves, which is how most diseases begin. Always hoe shallowly so you do not cut the roots running just under the surface.
Aphids, whitefly and red spider mite attack the foliage, above all under cover: apply potassium soap and neem oil. Caterpillars eat the leaves and are controlled with Bacillus thuringiensis. Root knot nematodes affect the roots in warm sandy soils. Grasshoppers and beetles chew the leaves at the height of summer, but the plant is vigorous and recovers: only in the first weeks is it worth netting the young plants.
Root and collar rot in waterlogged soil is the most serious problem. Leaf spots and powdery mildew appear in humid, enclosed conditions. Ensure drainage, wide spacing and good airflow. Do not repeat roselle or okra in the same bed in consecutive years, because they share the same root diseases, and do not wet the foliage when watering.
What you harvest is the fleshy calyx left after the flower drops, ten to twenty days after flowering, while it is still tender and snaps when squeezed. Picked late it turns woody. Twist the calyx to release it and push the seed capsule out from inside with a tube or your fingers. Dry in sun or shade and store in an airtight jar. Allow about 100 to 120 days from transplanting to the first harvest of this variety. The reference colour is deep red: harvest when the calyx is fleshy and fully coloured.
