What it is
Asparagus (Asparagus Officinalis) is a perennial flowering plant species in the genus Asparagus. It is long lived and once established the plants can last for 20 to 30 years. Its young shoots are a much sought after spring vegetable.
Asparagus is either male or female. The male plants produce more plentiful and larger spears so gardeners often prefer them. The female plants expend a huge amount of energy producing seeds and so provide less for your table.
In the past all asparagus varieties produced a mix of male and female plants. However, ways have now been found to effectively propagate all-male varieties of asparagus. So look out for all male varieties such as the Jersey Series when buying your seeds or crowns.
Asparagus is a vegetable for the patient gardener. It can be grown from seed or from mature crowns bought from a garden centre. The plant needs to establish a strong root system though so, if grown from seed, the shoots will not be ready for harvest for 3 or even 4 years. Even if grown from a crown, the shoots should not be harvested until the year following planting. In short, asparagus epitomises the saying "Good things come to those that wait"!
IN GREENHOUSE/ WINDOWSILL: February
Depth: 1/2" (1cm)
TRANSPLANT OUTDOORS: April to June
SOW CROWNS DIRECTLY OUTDOORS: April to June
Depth: 6" (15cm)
DISTANCE BETWEEN ROWS: 30” (80cm)
DISTANCE BETWEEN PLANTS: 20” (50cm)
HARVEST: May and June – (once plant is mature - see Timing above)
Asparagus does not like to have its feet “wet,” so be sure that your garden bed has excellent drainage. Raised Beds are a great place to plant asparagus and mean a lot less digging.
How to plant
Firstly, clear the bed and make sure there are no weeds. Then, work in a 2"-4" layer of compost, manure or soil improver.
Prepare shallow trenches about 12" (30cm) wide and 6" (15cm) deep. You might want to make these slightly deeper if you have sandy soil (8"/ 20cm) or slightly shallower if you have heavy soil (4"/ 10cm)
Space the crowns 15" to 20" (38-50cm) apart in rows that are 30" (80cm) apart. Spread the roots out in the trench with the buds pointing upward.
Lastly, once planted, completely fill in the trench with soil. In your grandfather's day many people used to gradually fill the trenches with soil as the plants grew but no one seems to do this anymore. When the trench is filled, add a 4-8" (10-20 cm) layer of mulch and water regularly.
For the first year, just let the asparagus grow to give the crown a chance to get well established. If growing from seed then repeat this for the next 2 to 3 years! The following spring, remove the old fern growth from the previous year. You should see new spears begin to emerge.
Though not a huge threat, the main threat to your asparagus is the Asparagus Beetle - read more about this in out Pests & Diseases: Asparagus Beetle Blog
Only harvest from established plants - see Timings above. Allow the shoots to grow to roughly 6” (15cm) then cut it 2” (5cm) under the ground with a sharp knife. This will give a partially blanched stem where the lower stem has had no light. The French, who are great lovers of asparagus, like to grow it under mounds, blanching them when the tops peek out. They then cut them 10” (25cm) under the ground. So if you prefer your asparagus white then this is an option.
The spears grow quickly so leave it no longer than every other day to check for spears ready to harvest. They will quickly become woody and inedible of you miss your window,
Once an asparagus spear starts to open and have foliage, it’s too tough for eating. Stop harvesting spears when the diameter of the spears decreases to the size of a pencil. At that point, it’s time to let them grow and gain strength for next spring.
Immature plants will have a season of only 2 to 3 weeks. With proper care though this will extend to up to 8 weeks for established plants.
When the harvest is over let the plants grow into fun leafy plants. Always leave at least one spear. Keep the area around them weeded to keep the plants strong. Cut back the asparagus to about 2" (5cm) above the ground in autumn when the foliage has died back and turned yellowy, brown.
Lastly, before cutting back, mark the bed well so that you don't accidently dig up your precious plants. Otherwise your patient waiting will have been for nothing!
Asparagus does not last for long, best to eat the spears as fresh as possible. It has to be one of the main benefits of growing it yourself to pick it straight from the garden to eat the same day. You can of course blanch them and then freeze them, but they are never as good.
If you do need to store them then the best way, if you have enough space in your fridge, is to treat them just like cut flowers and place the spears in a 2-3" of water. Alternatively, bundle the spears together, wrap the stem ends of the spears in a moist paper towel, and place the bundle in a plastic bag. Store in the salad drawer of your refrigerator.
Simple is best. Lots of melted butter or a simple Hollandaise Sauce are perfect accompaniments.