How to Grow Asparagus: A Practical Guide from Seed to Harvest

Asparagus is one of those vegetables that takes a little patience to establish, but once you've got a good bed growing, it can reward you with fresh spears every spring for many years.

Growing asparagus from seed takes longer than starting with crowns, but it's a much more economical way of establishing a larger bed. You also get the satisfaction of raising the plants yourself and watching them develop into something that could be producing crops for the next 15–20 years.

The important thing with asparagus is to think ahead. Unlike most vegetables, which we sow and harvest in the same season, asparagus is a perennial crop. Once planted, it will occupy the same ground for a long time.

I wouldn't rush the early stages. Give the young plants time to develop strong roots, choose their final position carefully and resist the temptation to harvest too soon.

Get those things right and asparagus is a surprisingly straightforward crop to look after.

When to Sow

Asparagus seeds are best started under cover from February to April.

I prefer sowing in March when the days are getting longer and there's enough time for the young plants to develop before they're moved outside.

You can sow later in spring, but an earlier start under cover gives the seedlings a longer growing season to establish.

Asparagus seeds germinate best in warmth, so a heated propagator can be useful.

Don't worry if the seedlings take a little longer to appear than you're used to with vegetables such as radishes or lettuce. Asparagus isn't a particularly quick crop at any stage, and germination can take several weeks.

How to Sow Asparagus Seeds

Asparagus seeds are reasonably large and easy to handle.

Soaking the seeds in warm water for 12–24 hours before sowing can help soften the seed coat and encourage germination, although it's not essential.

Fill small pots or deep modules with good-quality seed compost.

Sow the seeds around 1–2cm deep, cover with compost and water gently.

Keep them somewhere warm, ideally around 20–25°C, while they germinate.

Germination can take two to four weeks, sometimes longer, so keep the compost moist without leaving it waterlogged.

Once seedlings appear, move them into plenty of light.

The first shoots are quite delicate and look rather different from the familiar asparagus spears we eventually harvest.

Growing Seedlings On

Asparagus seedlings develop fine, feathery foliage as they grow.

If you've started them in small modules, move the seedlings into individual deeper pots once they're large enough to handle.

Asparagus develops an extensive root system, so don't leave plants cramped in small containers for too long.

Keep them somewhere bright and frost-free while they're young, watering when necessary.

There's no need to feed heavily at this stage. Fresh compost should provide enough nutrients initially, although plants growing in pots for several months may benefit from an occasional balanced liquid feed.

As the weather improves, gradually harden off the young plants before moving them outside.

The aim during this first season is to produce healthy plants with strong developing roots rather than anything to harvest.

Choosing the Right Position

This is probably the most important decision you'll make when growing asparagus.

Because plants can remain productive for many years, it's worth taking the time to prepare the ground properly.

Choose a sunny position with fertile, well-drained soil.

Asparagus doesn't enjoy sitting in waterlogged ground, particularly during winter.

If your garden has heavy clay, improving drainage or using a raised bed may be worthwhile.

Remove perennial weeds before planting. Couch grass, bindweed and other persistent weeds are much easier to deal with before asparagus becomes established.

Work some well-rotted compost or organic matter into the soil to improve its structure.

I wouldn't choose a position where you're likely to want to dig everything up again in a couple of years. Asparagus needs a permanent home.

Planting Out and Spacing

Young asparagus plants can be moved into their final positions once they're well established and conditions are suitable.

You can plant sturdy seedlings in late spring or early summer after hardening them off, or grow them on in a nursery bed or pots before planting them in their permanent positions the following spring.

Space plants around 30–45cm apart, allowing approximately 90cm between rows if you're establishing a larger bed.

Unlike planting mature asparagus crowns, seed-grown plants don't need to be placed into deep trenches.

Plant them at approximately the same depth they were growing in their pots, taking care not to damage the roots.

Firm the soil gently around the plants and water thoroughly.

The young plants may look rather small for the amount of space you're giving them, but remember that mature asparagus develops a substantial root system and a large amount of fern-like summer growth.

Growing Asparagus in Pots

You can raise asparagus seedlings in pots, but I wouldn't recommend keeping mature asparagus permanently in an ordinary container if you want a productive long-term crop.

Asparagus develops a large root system and needs plenty of space to establish.

Pots are useful during the first growing season, particularly i