It has to be said, first of all, that growing vanilla is not a beginner's pursuit. However, if you are an accomplished and experienced gardener looking for a real challenge then you may like to give this tropical exotic a go. Vanilla is a vining member of the orchid family and can be very fussy. Like some other orchids, it will need tender attention and the perfect environment before it will set a crop. If you manage to get some vanilla beans, however, you will surely gain a lot of satisfaction that all your immense efforts and expense have paid off.
Growing vanilla basically requires the faithful recreation of the tropical environment where these vines naturally grow. 3-5 year old plants are available to by from a number of sites online and should be potted into pots slightly bigger than the pots they have arrived in. The growing medium should be a specialist orchid compost. Make sure that as you pot up, you also add support structure/ stakes up which the vanilla vine can climb.
Vanilla vines are extremely sensitive to heat, light and moisture and all three will have to be perfect in order to have success with these plants. The temperature in your heated polytunnel or hothouse must be kept consistently at 26-7 degrees Celsius. The bright but diffuse light in a polytunnel should be fine. The water requirements are complicated as in order to produce pods, the vanilla vines will require distinct wet and dry seasons. For the wet season, keep humidity high and keep the surface of your container moist continually.
The vine must be stressed by being deprived of water for 6-8 weeks in order for its to produce flowers. Bear in mind, however, should you have bought a younger plant, that plants will be at least three before it will produce any flowers. Flowers will appear on the shoots that point down towards the ground.
You will need to pollinate the flowers in order for beans to form. To pollinate, remove the lip of the flower. Take the pollen from the anther area of the flower and place it in the nectar-containing stigma, a flap on the top, right column behind the flower. Pollinated flowers will then produce the green beans. These beans must then be left on the vine for six months to allow the vanilin (which gives the vanilla flavour) to develop.
It is time to pick the beans when the ends begin to turn yellow. However, the work does not end there. Beans should be wrapped in a blanket for 48 hours and will develop a light brown colour. After this, beans should be dried in the sun for a month or more. When the beans turn dark and leathery then they are ready to use. (Alternatively, you could choose to explore UK alternatives to vanilla, such as sweet woodruff, meadowsweet, or sweet clover – these common plants, when dried, can be infused into custards and other desserts as with vanilla as long as these coumarin containing plants are used in moderation – take care and always take advice if not an experienced forager).