How To Grow Asparagus

Asparagus is a wonderful crop to grow in any home garden. Perennial in nature, it provides delicious shoots for you year after year, in some cases for multiple decades. This is due to their amazing root systems that store energy underground after the growing season meaning that with the right care, asparagus will flourish in your garden.

Thriving in temperate and cool climates but performing in subtropical regions of Australia, this growing guide will teach you how to grow asparagus from crowns, when to plant asparagus, how to harvest asparagus, and more.

Asparagus Classification

Family

Asparagaceae.

Genus

Asparagus officinalis.

Asparagus Varieties

There are over 300 species of asparagus with the Mary Washington variety being the most popular. Green asparagus, white asparagus, wild asparagus, and Apollo asparagus are also very popular globally, as well as Atlas asparagus and Jersey asparagus.

Why Grow Asparagus from Crowns?

Crowns are a part of the plant with an attached root system. Mr Fothergill’s supplies asparagus crowns as two-year-old bare-rooted crowns in the winter sowing bulbs season, for planting in winter to early spring.

The main advantage of growing from asparagus crowns compared to seeds is that they will establish in your garden much faster as they take quite some time to get going. This is important not only for the size of the asparagus spears but the quantity you can harvest over the picking season.

Asparagus enjoy full sun in a well-dug deep soil, with plenty of organic matter. A soil pH of roughly 6.5 to 7 is ideal and if your soil is more acidic, improve it with an alkalising product such as wood ash (potash) or horticultural lime to raise the soil pH.

Only apply a soil amendment if you have tested your soil with an at-home pH kit as it may not require any treatment at all.

Prepare your garden bed with garden hand tools such as a garden fork to a depth of at least 30cm, mixing in aged cow or poultry manure as you go. You can also try the trench method for larger plantings or in heavy clay soils.

To grow asparagus in trenches, dig a long channel approximately 40cm deep and 20cm wide, making sure it’s long enough to space each asparagus crown 20-30cm apart.

In the bottom of your channel, lay high-quality garden compost and aged manure, and mix it around with some of the original soil. This will improve the drainage and fertility deeper in the soil where the roots will spread. Mound up the compost mix in the trench towards the middle, leaving about 10-15cm from the top to your surrounding soil level.

Before planting the crown, soak it in some plain water or compost tea for an hour or so, to kickstart the rehydration process. After soaking, pop the crown on the top of your soil mound in the trench, allowing the roots to spread out around the sides. Backfill with more soil covering the top of the crown to a depth of about 10cm.

Now that your crowns are planted and ready to roll, the waiting game begins. We suggest mulching between rows and beds at this time to keep down the weeds. You should also ensure that any mulch around the young crown is not too thick and heavy to where shoots will struggle to push through. Sugarcane mulch is great for this.

Remove weeds and grass as they appear as they will be stealing nutrients and moisture away from your asparagus crop.

Asparagus are hardy once established, but it’s important to keep an eye on the soil moisture, particularly in the spring and summer. In dry climates, you may need to water more deeply regularly, depending on if the soil is moist when you dig down a few centimetres.

In the first year of planting, give your crop a light top dress of balanced feed in the spring, as remember, we put all that compost underneath in the winter. When growing asparagus crowns, skip harvesting for the first season or two and allow them to put on lots of lush leafy growth. This energy from the leaves will redirect into the crown over winter, which means better quality harvests the following year.

Once the leaves and stems die down in the winter, turning dry and yellow, remove them at ground level and leave room for new growth in spring. This will open up your garden bed again, which will allow you to remove any weeds or grass that has snuck in. Apply a thin layer of compost, aged manure, and mulch over the top of the now-dormant crowns in preparation for spring.

When you have patiently waited a season or two for your crown to mature, you can start with some light harvests on the new season spears that push through the mulch. Pick these regularly over a week or two to begin with, and the following season extend the harvest timeframe by another couple of weeks and so on.

Harvest asparagus spears and catch them before the buds begin to open out and they’re still juicy and young. Once open they will become fibrous so are not too pleasant to eat.

With any well-established asparagus crop, you don’t want to exceed harvest time by more than a couple of months as this will deplete your harvests for the following year. After your set picking season, ensure you allow the rest of the spears to mature into adult leaves because these will replenish the energy stored in your crowns at the end of the season.

Avoid walking over your beds or trench planting lines where the crowns are contained, especially in the lead-up to spring. Any foot traffic or compaction can break the developing spears underground or make it harder for them to push through the soil.

For white asparagus that has a milder flavour, try excluding light from your spears before they break through the soil with tubs or tarps. The lack of sunlight will prevent the crop from turning green.