Of all the many options open to greenhouse growers when it comes to choice of plant, it could be argued that one of the most satisfying is producing things you can then go on to eat.
Herbs are possibly the most straightforward of these edible plants – and they perform very well in a greenhouse.
Borage – also known as the starflower – is one such plant. Native to the Mediterranean region, it has long since become naturalized all over the world. It can grow anywhere between two and 3.3 feet and is characterised by bristly, hairy stems and leaves.
Its flowers have five narrow, triangular-pointed petals and are most commonly a vivid blue color, although pink varieties have been recorded in the past and white flowers can also been cultivated.
Temperate climates usually see the borage bloom over a fairly long summer – from June to September – but in milder climates, it has been known to blossom continuously throughout the year.
In terms of its culinary properties, the flowers and leaves taste similar to cucumber – and this makes them an excellent garnish for a summer cocktail. For instance, they can add flavor and color to a refreshing highball – such as the spicy-sweet Pimm's.
Tulbaghia violacea – also known as society garlic – is another great edible flower to grow in a greenhouse. It is indigenous to South Africa and has historically been used as a herbal remedy for the treatment of a wide range of ailments.
The pretty purple leaves have a garlicky taste – and as a result they are great for giving some character to a salad. It is named 'society garlic', as it is considered to be less likely to cause the kind of bad breath that is commonly associated with the consumption of traditional garlic. This property makes it much more socially acceptable to eat in polite company.
Growing up to 24 inches tall, the plant has narrow leaves and large clusters of fragrant violet flowers. These bloom a little later than the borage, usually from midsummer to fall. It is well-suited to greenhouse growing as it will need a degree of protection from frost in the colder winter months.
Bunny Guinness – chartered landscape architect and author of the Family Gardens book – compared tulbaghia violacea to purple alliums, which are slightly better-known. In an article for UK national newspaper the Daily Telegraph, she added that they are slightly hardier than alliums, despite looking more delicate.
"The foliage is a big asset, too. They … tolerate down to around -9C/15F and favour a sunny position," Ms Guinness commented.
"They benefit from dividing every two to three years and apart from cutting back the old foliage in November, you need do little else," the expert continued, adding: "They work well in a pot and the variegated form."
Ms Guinness claimed that she chose to plant her tulbaghia violacea en masse, sprinkling them throughout a border full of topiary – which could an alternative for greenhouse growers to to consider.