Known as a bath sponge produced from the mature fruit, the luffa is also prized as a vegetable when harvested very young.
Sometimes known as sponge gourd, the luffa (or loofa) is probably best know for the bath sponges that are made from its mature fruit. In some parts of the world, however, luffas are equally prized as a vegetable, when they are braised or cooked in curries by Asians, Chinese and Thais.
To be use in the kitchen, the fruit should be harvested when they are 20 cm long. At this stage they are soft and have a puffy texture when squeezed. However, if left on the plant they will mature to twice the size (40-50cm long). At this point the fruit are inedible as they have an inner network of tough fibres – the very fibres that makes them excellent as sponges.
The plants are heat lovers and must be grown in a tunnel or greenhouse, however they are vigorous growers and will take over whatever structure they are grown in, shading out any other crop grown near by.
To make a sponge bath the fruit must be allowed to mature fully on the plant. If there is enough growing time the fruit will dry out and turn brown naturally on the vine. Unfortunately, in the UK with our short summers it is highly possible the fruit will still be green in the late autumn. If this is the case the flesh and skin have to be “retted”, i.e. soaked in water to rot the flesh. The easiest way to do this is to keep them submerged in a trough or bucket of water – the fruit will float so will need to be weighted down. It takes about 1 to 2 weeks for the flesh to rot sufficiently so it comes off easily. At this stage, the skin simply falls off to reveal the fibrous sponge inside. Allow the sponge to dry, shake the seeds out, and you have your luffa! If you want a pure white bath sponge a few minutes soaking in dilute bleach will do the job. They make wonderful Christmas presents.
Please note: The seed needs a temperature of 27˚C to germinate, even then they are slow to emerge and come up erratically (so be patient).
Approximate number of seeds per pack: 8