Asparagus plant care: watering, fertilising & more


With a passion for growing installed at an early age, I have always been happiest outdoors in nature. After training as a professional gardener and horticultural therapist, I currently run horticultural therapy and community kitchen gardens in the UK, helping others access the many physical and mental health benefits of growing vegetables, fruit and plants.

Favourite fruit: apples and pears
Favourite vegetable: asparagus

Asparagus is not only found in delicatessens and restaurants, but many home gardens as well. Read on to learn more about how to water, fertilise and care for asparagus plants.

An asparagus plant being fertilised
To get the best harvest asparagus needs to be fertilised. [Photo: Jomyoothphoto/]

Asparagus (Asparagus officinalis) has to be one of the most rewarding vegetables to grow as nothing quite beats the taste of freshly picked asparagus from the garden. With a short but much awaited harvest period, you’ll want to do everything you can to encourage lots of tasty spears come late spring. We’ll cover how to care for asparagus plants to make sure they remain healthy, strong and ready for harvest time.

Asparagus plant care: watering

Watering asparagus is essential for it to thrive and to crop well, come spring. Asparagus plants require a moist, but well-drained soil or bed and need adequate moisture during the active growing season and especially whilst establishing.

After planting, it is recommended to water asparagus weekly during the growing season for at least the first two years and then on as necessary. However, it is important not to overwater, especially if the soil is not light and free-draining as this can lead to the crowns rotting. To test if asparagus needs watering, check the top layer of soil with a finger down to 5cm deep and if it is dry then it can be given a slow and thorough watering.

Where possible, harvested rain water should be used, although mains water at room temperature will suffice if required.

When the harvesting period comes to an end, the spears are allowed to mature into tall feathery stems that are cut down to ground level when they die back in winter. As summer progresses, watering can be reduced and stopped in the autumn when the plant goes dormant until the following spring.

Tip – To keep the soil moist, especially during the summer months, seep or soaker hoses can be used to provide regular moisture to the base of the plants.

Fertilising asparagus

Asparagus plants are fairly heavy feeders and benefit from an annual mulch and feed to ensure the best crop.

Asparagus thrives in a rich and fertile soil. On planting and annually thereafter in late winter it is recommended to apply a layer of organic matter or well-rotted manure, which will help conserve moisture, suppress any annual weeds and enrich the soil by providing food for underground microorganisms.

In early spring before harvest season starts, a general fertiliser can be applied. Our Plantura All Purpose Plant Food is ideal, as being slow-release it will feed the plants for the coming months and provide all the key nutrients, especially nitrogen, required to encourage strong growth.

All Purpose Plant Food, 1.5kg
All Purpose Plant Food, 1.5kg
  • Perfect for a variety of plants in the garden & on the balcony
  • Promotes healthy plant growth & an active soil life
  • Long-lasting fertiliser that is free from animal products - child & pet friendly

Pruning asparagus plants

Asparagus plants require pruning or cutting back annually at the end of the year. Once spears have been left to grow into large feathery stems over the summer months, they can be cut down to ground levels using a clean and sharp pair of secateurs. However, this must only be done once the asparagus crowns have been replenished and the foliage has turned yellow and died back.

The died-back foliage should not be added to any home compost systems due to any potential contamination from pests and disease, but be removed and carefully disposed of instead.

Common pests and diseases

Once established, asparagus generally grows trouble free and crops reliably every spring. However, there are some asparagus pests and diseases that can result in poor yields:

  • Asparagus beetle:

Present in North America and Europe the asparagus beetle (Crioceris asparagi) eats the foliage and can subsequently reduce harvest yields the following year. The adults are 6mm to 8mm long, with a colourful red head and six yellow markings on their back, making them easily identifiable. The eggs and larvae are less obvious, but on closer inspections the tiny black beetle eggs can be seen sticking out horizontally off the spears, which turn into black-brown larvae up to 10mm in length. Smaller numbers can be tolerated with little damage or controlled by picking off by hand or encouraging predators, such as ground beetles. Larger infestations may need to be sprayed with natural pyrethrins insecticides.

  • Stemphylium purple spot

Asparagus purple spot is a fungal disease caused by Stemphylium vesicarium that affects both the asparagus spears and foliage. Most common in cool and wet summers, stemphylium purple spot can lead to defoliation and reduced harvests the following year. Identifiable by its oval purple marks on the stems, which if spread, can cause the needles to turn brown and drop. If purple spot is suspected, all affected stems and debris need to be removed at the end of the growing season and disposed of carefully.

  • Rust:

Asparagus rust (Puccinia asparagi) is a fungal disease identified by orange or brown lesions on the stems and foliage. Often present during wet summers, asparagus rust can cause dieback and reduced harvests. Prevention measures that can help avoid rust taking hold include planting rust resistant cultivars including the Jersey varieties, planting at the recommended spacing and planting any new asparagus plants in a separate bed away from any rust affected plants. If asparagus rust is identified, any affected stems must be removed and destroyed, and any debris cleared from around the growing site.

  • Slugs and snails:

Causing damage to young asparagus plants and seedlings, slugs and snails can wipe out an entire sowing overnight if undeterred. Feeding off the leaves and stems, these gastropods can often be identified by their slime trails and feeding holes they leave behind. Control measures can include encouraging predatory wildlife into the garden, placing barriers around susceptible plants and removing them by hand.

Here in the UK, we tend to mainly grow asparagus that produces green spears, but for something even more eye-catching, why not try a purple or even white variety.

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