Asparagus
Asparagus is a perennial plant, so once it’s in the ground, you can be harvesting its spears for decades, and the returns are exponential. It’s got to be one of the most reliable long-term investments available!
You will need some asparagus crowns to get you started. These little plants are sold bare-rooted in winter, when they’re dormant, and this is the best time to plant them. Grown from seed, they are generally one or two years old and come packed in peat or sphagnum moss. Inspect crowns before buying, avoiding those with dry, shrivelled or rotten roots. You can also acquire crowns from a mature asparagus clump. If a friend has one, ask if you can dig up a section and separate the plantlets. Wrap the roots in moistened newspaper until you’re ready to plant them out.
A crop of asparagus needs a bed of its own, where it can dominate without being disturbed. Choose a sunny, protected spot without any competition from tree roots. Asparagus likes it rich, so make sure you add plenty of compost and manure when you’re preparing the soil, and mound the soil in a row to improve drainage. Make a trench 20–30cm deep in the row, then create a little mounded ridge along the bottom of the trench. Space the crowns 40cm apart, spreading the roots over the mound, and cover with about 5cm of soil. Water in, then water sparingly until the crowns start growing in spring.
Sorry to break this news, but you need to practise restraint by not harvesting any spears for the first year or two, in order to allow the plants to establish. Tough call, but that’s long-term investments for you!