RHS Growing Guides
How to grow asparagus
Our detailed growing guide will help you with each step in successfully growing asparagus.
Getting Started
Delicious, juicy asparagus spears are relatively easy to grow, and although you won’t get a crop for the first couple of years, after that you’ll have reliable harvests every spring for up to 20 years.
Succulent, tasty asparagus spears can be harvested for about eight weeks every spring
Asparagus is harvested for about eight weeks in spring and early summer, so is an annual treat to be anticipated and savoured. Asparagus spears are also quite expensive to buy, so are well worth growing if you have the space. An established plant should produce about 10 spears per season. After the harvesting period, shoots should be left to grow into tall ferny plants over the rest of the summer. Then simply cut them down to the ground in autumn, and they will re-sprout in spring, ready for harvesting again.
Month by Month
Jobs to do now
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Choosing
Different asparagus varieties produce spears of various sizes and colours
Asparagus plants are either male or female – male plants produce more and better spears, so many modern varieties are all-male. Most crowns offered for sale are all-male F1 hybrids. Older, non-hybrid varieties produce both male and (less productive) female plants. The female plants also produce seedlings that need to be weeded out to prevent competition with the existing plants. Even all-male F1 seeds can produce the occasional female plant.
When choosing varieties, also consider the quality of flavour, colour, spear size and overall harvest size. Some varieties produce early or late harvests, so if you grow several different varieties you can have spears over a longer period. For reliable cropping, look for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in our trials – see our list of AGM fruit and veg and our Recommended Varieties below. For more veg-growing inspiration, visit the RHS gardens, which all grow a wide range of vegetables, so you can compare varieties and pick up growing tips.
What and where to buy
Recommended Varieties
This all-male variety produces a mid- to late-season crop of tasty, straight spears, the quality of which only improves as...
A tried-and-trusted heritage variety that produces an exceptionally large crop. The bright green spears have deep...
A prolific-cropping, early-season, male variety producing medium-thick, mid-green spears with closed purple tips.
Preparing the Ground
Create your asparagus bed in a warm, sunny, sheltered spot with free-draining soil
A planting site in full sun is preferable, but asparagus will also tolerate dappled shade. Most soil types are suitable, as long as they’re well drained. If you have heavy soil, make a raised bed to provide better drainage. A pH of 6.5–7.5 is ideal, so if your soil is more acidic than this, add lime to raise the pH. Weed the bed thoroughly before planting, then dig in at least a bucketful of organic matter, such as garden compost or well-rotted manure, per square metre/yard.
Sowing
The quickest and easiest way to start an asparagus bed is to buy bare-root crowns (see Planting below), but you can also grow asparagus from seed. Although seeds are a slower option and not quite as easy, they are cheaper to buy, and one packet could give you lots of plants. You can sow asparagus seeds either indoors or outside.
Sowing indoors
Sowing outdoors
Planting
Enrich the soil with garden compost, then gently spread out the roots of each crown
Dig a trench 30cm (1ft) wide and 20cm (8in) deep. Fork garden compost or well-rotted manure into the base, then cover with a 5cm (2in) layer of the excavated soil. Make a ridge of soil along the centre of the trench, 10cm (4in) high. Place the crowns on top of this ridge, with the growing points or new shoots uppermost, spacing them 30–45cm (12–18in) apart. Spread the roots out evenly, but handle carefully as they break easily. Mix organic matter into the excavated trench soil, then gently return this enriched soil back into the trench, leaving the bud tips just visible. Space rows 45cm (18in) apart and stagger the plants between adjacent rows. Water the plants well, to settle to the soil around their roots, then mulch with a 5cm (2in) layer of well-rotted manure or garden compost, to hold in moisture and suppress weeds.
Plant Care
Looking after established asparagus is straightforward – just weed regularly, apply mulch and put supports in place to keep these tall plants from being blown over. At the end of the season, when the foliage turns yellow, cut all the stems down to the base.
Let asparagus grow to full size over summer, then cut plants to the ground in autumn
Watering
Water new asparagus plants regularly throughout their first summer. Once established, asparagus is drought tolerant, so only needs to be watered in long dry spells. For water-wise advice, see our guides below.
Mulching
Apply a thick layer of mulch to the soil in late winter to discourage weed germination and hold moisture in the soil. You could also consider covering the soil with weed-suppressing membrane from autumn to late winter, while the asparagus is dormant, to prevent annual weeds germinating. It’s important not to let weeds get established in an asparagus bed, as removing large or widespread weeds can easily damage the shallow roots of asparagus plants.
Feeding
In most soils, established asparagus plants should crop reliably without additional feeding, especially if the soil is regularly mulched with organic matter. But if growth is poor, you could apply a high potassium general fertiliser in early spring, before the new spears sprout.
Weeding and removing female plants
Keep the soil weed-free, as asparagus grows better without competition from other plants. Weed by hand rather than with a hoe, as asparagus plants have shallow roots that are easily damaged. If you have any female plants (which produce orange-red berries), weed out any seedlings they produce. If you’re growing an all-male variety, you may still find the occasional female plant, which you should remove.
Supporting plants
Asparagus grows into a tall, feathery plant over the summer. To prevent the stems breaking in windy weather, which could damage the crown, support plants using stakes and twine to make a ‘fence’ either side of the row. You could also add netting, secured to the stakes about 50cm (20in) from the ground, for extra support.
Put stakes, string and netting in place early, to support asparagus plants as they grow
Propagating
To make more plants, you can divide well-established crowns in late winter or early spring. Do this no more than every three years, as the plants can be slow to settle back in afterwards. Dig up the crown, handling it carefully. Gently prise it apart into several smaller sections, each with several growing points, taking the strongest parts from the edge of the crown. It may be necessary to cut some roots if they can’t be pulled apart. Discard any old, woody parts. Replant the new sections straight away (see Planting, above), with the growth buds visible at the soil surface.
Harvesting
Use a sharp knife to cut through the spears just below the soil surface
To harvest, cut individual spears with a sharp knife 2.5cm (1in) below the soil surface when they’re no more than 18cm (7in) tall or about finger thickness. In warm weather, harvest every two to three days for the best quality spears – they grow quickly and soon turn woody. Regular harvesting also encourages more new shoots to be produced. Expect an established plant to provide about 10 spears over the harvesting period.
Problems
Asparagus is generally trouble free, cropping reliably every spring. However, slugs, snails and asparagus beetles can cause problems, late frosts can damage young shoots in spring, and damp, poorly drained soil can cause the roots to rot. For tips on remedying these issues, see Common problems below.
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