How to Plant Asparagus Plants

Asparagus is a perennial crop that can produce harvests for up to twenty years if planted and maintained properly. While it takes time and patience to establish, the long-term rewards make it a favourite among gardeners. Planting asparagus involves preparing a dedicated bed, selecting the right variety and understanding the plant’s seasonal growth cycle. Once settled, asparagus requires relatively little work compared to annual vegetables.

Getting Started

Before planting, it's important to understand that asparagus doesn't offer instant results. The first couple of years are all about establishment rather than harvest. Whether you're growing from crowns or seeds, asparagus prefers a sunny, sheltered site with well-drained soil. Crowns are more common for home gardeners, as they reduce the waiting time to the first crop. Seeds can be used too, but they add an extra year to the growing timeline.

How Many Varieties Are There

There are several varieties of asparagus available, each with slightly different characteristics. Some are better suited to colder climates, while others produce earlier harvests or thicker spears. The main types include green, purple and white asparagus, though white is usually created by excluding light from green varieties. Most UK gardeners grow green asparagus, which is hardier and easier to maintain in home settings.

Choosing Which Variety

When selecting a variety, consider your growing conditions and harvest goals. ‘Gijnlim’ is an early, high-yielding green variety well-suited to UK gardens. ‘Pacific Purple’ is sweeter and more tender, ideal for raw eating or quick cooking. If disease resistance is a concern, varieties like ‘Backlim’ or ‘Ariane’ offer good resilience against common issues such as rust or crown rot. It’s also worth checking if the variety is all-male, as these tend to produce more spears and are generally more vigorous.

Preparing the Ground

Asparagus needs deep, fertile soil that drains well. Choose a spot that gets full sun and clear it of weeds thoroughly. Dig over the soil to a spade’s depth, mixing in plenty of well-rotted manure or compost to boost fertility. Because asparagus roots spread wide and deep, avoid planting near tree roots or other aggressive perennials. Raised beds can also work well, particularly if your native soil is heavy or poorly drained.

Sowing

Growing asparagus from seed is possible, though it’s slower than planting crowns. Sow seeds indoors in early spring and keep them warm until they germinate. Once the seedlings are large enough to handle, they can be transplanted into the ground or larger pots to grow on. You’ll need to wait an extra year or two compared to crowns before harvesting, but some gardeners prefer seed-grown plants for their vigour and longevity.

Planting

Crowns are usually planted in early spring, once the soil has warmed up. To plant, dig a trench about 30cm wide and 20cm deep. Make a ridge of soil down the centre, then place the crowns on top, spreading the roots out evenly. Cover with soil until just the tips are showing, and fill in the trench gradually as the shoots grow. Space crowns about 30 to 45cm apart, allowing room for the plants to mature and spread.

Plant Care

In the first year, focus entirely on helping the plant establish. Water during dry spells and keep the bed weed-free to reduce competition. Mulching with compost or straw helps retain moisture and suppress weeds. Once the plants are established, they need little maintenance beyond regular feeding with a balanced fertiliser in spring and again after the harvest season ends. Cutting back the yellowed ferns in autumn helps reduce disease and encourages strong growth the following spring.

Harvesting

As tempting as it may be, avoid harvesting spears in the first year or two. Letting the plant grow undisturbed strengthens the root system. In the third year, you can begin harvesting for a short period—around four weeks. By year four, you can extend the harvest to six or eight weeks. Always cut spears when they’re about 15 to 20cm tall, using a sharp knife just below the soil surface. Stop harvesting when thinner spears start to appear, allowing the plant to recharge for next year.

Problems

Asparagus is relatively low-maintenance once established, but there are a few potential problems. Slugs and snails can damage emerging spears, especially in spring. Asparagus beetles may appear later in the season, feeding on the foliage and laying eggs on the spears. Rust is a common fungal disease, especially in damp summers. Good air circulation, regular weeding and removing old growth in autumn can help prevent most issues. Crowns can rot in poorly drained soil, so if that’s a risk, consider raised beds or improved drainage.

Timing Matters

Asparagus is best planted in early spring, once the soil begins to warm. In the UK, this usually falls between March and April, depending on your region. Planting at the right time gives the crowns or seedlings the entire growing season to settle in. Cold, wet soils can slow root establishment or even cause rot, so avoid rushing it if conditions aren't ideal. Preparing the site ahead of time can help you plant at the right moment without delay.

Soil Temperature and Depth

Soil temperature plays a crucial role in early root development. Asparagus prefers soil that has reached at least 10°C. Using a soil thermometer can help you judge this accurately. When planting crowns, ensure the final soil depth is about 5 to 10 cm above the crown itself. Covering the crowns too deeply at the start can lead to slow growth, while planting them too shallow can expose them to frost and drying winds.

Watering Technique

Water is important in the early stages but asparagus dislikes soggy conditions. Once planted, water thoroughly and then allow the top few centimetres of soil to dry before watering again. During dry spells, especially in the first year, regular watering supports root development. Once the plants are established, they become relatively drought tolerant. Avoid overhead watering as this can encourage fungal diseases; watering at the base is best.

Feeding and Soil Health

Asparagus benefits from fertile soil that’s replenished each year. In early spring, apply a top dressing of general-purpose organic fertiliser or blood, fish and bone. After the harvest season ends, feed again to help the plant store energy for the next year. Keeping the soil well-fed and well-structured ensures strong spear production and reduces the risk of nutrient deficiency. A layer of well-rotted manure in autumn helps improve both fertility and soil structure.

Mulching for Better Growth

Mulching is particularly helpful for asparagus beds. It helps to retain moisture, suppress weeds and keep soil temperatures more consistent. Use organic mulch such as straw, composted bark or leaf mould. Avoid piling it directly onto the crowns or young shoots. Reapply mulch each spring to maintain soil health and reduce the need for hand-weeding throughout the growing season.

Long-Term Bed Management

Since asparagus is a perennial crop, planning for the long term is essential. Choose a bed that can be left undisturbed for at least a decade. Avoid planting other crops in the same area, as the asparagus roots spread wide and deep. Keeping the bed dedicated to asparagus helps reduce disease and nutrient competition. Over time, some replanting or dividing may be needed if productivity drops, but a well-managed bed can remain productive for many years.

Protecting the Bed in Winter

Asparagus ferns die back in autumn and can be cut down once fully yellow or brown. Removing the old growth prevents pests from overwintering and keeps the bed tidy. Applying a fresh layer of mulch before winter helps protect the crowns from frost damage. In colder areas, covering the bed with fleece or straw can offer extra protection and improve early spear growth in spring.

Starting with Seeds vs. Crowns

Most home gardeners start asparagus from crowns because it saves time. However, growing from seed is cheaper and may give you a healthier, longer-living plant since it adapts to your soil from day one. The catch is time. Seed-grown asparagus takes an extra year or two to start producing and needs careful weeding while it’s small. Crowns offer a faster route to harvest, but they're more vulnerable to transplant shock if not handled carefully. If you're patient and enjoy the process, seeds are a good long-term investment.

Importance of Weed Control

Weed control is essential, especially in the first couple of years. Asparagus hates competition, and weeds will rob young plants of moisture and nutrients. Once established, the dense fern-like growth helps suppress weeds, but early on, you’ll need to stay on top of it. Hand-weeding is safest, as hoeing or cultivating too deep can damage the roots or crowns. Applying mulch early in the season also helps reduce the amount of weeding required.

Supporting Fern Growth

After the harvest period ends, asparagus sends up tall, feathery fronds known as ferns. These aren't just for show—they’re critical for plant health. The ferns capture energy from sunlight and channel it back into the roots to fuel next year’s spear production. Avoid cutting them down until they naturally yellow and die back in autumn. In windy areas, tall ferns might need light support to prevent breakage.

Managing Spear Thickness Over Time

Over the years, you might notice a decline in spear size. This is natural as plants age, but it can also signal over-harvesting or soil nutrient depletion. Allowing some spears to mature into ferns each year helps the plant recover. Regular feeding and soil care can slow this decline and keep your plants productive for longer. If spear size consistently drops year after year, it may be time to divide the crowns or replant a fresh bed.

Replacing or Dividing Old Plants

After 10 to 15 years, asparagus beds may start to lose vigour. At that point, you can either replace the bed entirely or divide and replant the healthiest crowns in fresh soil. This is best done in early spring before growth resumes. Dig up the crowns carefully, cut away any dead or rotting sections, and replant the healthy portions with adequate spacing and fresh compost. This gives your asparagus a second life and keeps your patch productive.

Wildlife and Asparagus

While asparagus is fairly resistant to common garden pests, wildlife can sometimes pose a threat. Birds may peck at young spears, especially in early spring. Netting can help if this becomes a problem. In rural areas, rabbits and deer might browse the tender new growth. Fencing or using natural deterrents can help protect your plants during vulnerable stages.