MOST of the vegetables we grow are annuals.
They grow quickly, and are ready for harvest in only a few months, sometimes weeks.
Some crops, such as cauliflower or cabbage, provide just one harvest.
With others, such as peas and beans, we continue picking for a month or two, and then it's all over.
There are some vegetables that will persist for a bit longer - I'm thinking here of things like eggplant and chilli, which can enter a semi-dormant state over winter and then start producing again in their second summer.
And then there are the perennial vegetables that will live and produce for over two years.
Perhaps the most popular of all perennial vegetables is asparagus.
An asparagus plot can produce for over 15 years once established.
So you plant a few crowns in winter one year, and then it's there for good.
Asparagus (Asparagus officinalis) is a member of the lily family.
The fern-like foliage grows to about 1.5m if it is not harvested for consumption as a young shoot.
This is a nutrient-rich vegetable, high in folic acid and a good source of potassium, fibre, vitamins B6, A and C and thiamine.
It contains no fat, no cholesterol and is low in sodium.
It tastes delicious, and, because it can be expensive to buy, it's a great crop to add to the home garden.
It's incredibly easy to grow.
Plenty of room and plenty of patience are the main requirements, as it takes a couple of years for an asparagus bed to become productive.
The best way to grow asparagus is by planting crowns, which are established root systems with dormant top growth.
Crowns are available for a brief period in winter.
Asparagus will also grow from seed, but crowns will produce more quickly, because they are already about two years old.
You need to plant at least six crowns to get a decent crop in the first few years, but plant more if you have the space.
Because asparagus will remain productive for many years and doesn't like to be disturbed, you must choose a position where it can be left alone. A sunny, well-drained position is key.
Dig the soil deeply and add plenty of organic matter. Asparagus performs best when the soil pH is 6.5-7.5, so you will probably need to add some lime too.
Make a trench about 25cm deep, and make a little mound at the bottom of the trench. Plant the asparagus crown on this mound, spreading the roots out.
Under ideal conditions, shoots can grow 25cm in 24 hours.
Once your bed is established, you will need to harvest every day.
Watch out for slugs and snails, and mulch to prevent weed growth.
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