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Asparagus

Asparagus is a perennial vegetable that dies down in winter and regrows each spring. It is part of its own asparagus family (Asparagaceae) but was formerly considered part of the lily family, which also includes onions garlic and leeks.

Asparagus is native across much of Europe. The edible part of asparagus is the new shoot known as a ‘spear’. Left unharvested, it forms clumps of tall, woody, cane-like growth with ferny leaves. Asparagus spears are low in calories but high in folates, dietary fibre and vitamins A, C and K. It can be eaten raw, steamed, or grilled.

Follow our seven easy steps to successful asparagus harvest including tips along the way

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When to plant

Asparagus can be grown in all regions, but does best in areas with long, cold winters and mild summers. Check with your hardware or garden centre for advice on the suitability of asparagus to your location.

  1. Asparagus can be sown from seed, it is the cheapest option, but take three to four years from germination to harvest.
  2. For a quicker harvest, asparagus is usually planted in winter when it is available as a crown, the name given to the dormant root system.
  3. Potted plants are also available from spring to autumn and are ready to plant directly into a prepared garden bed.

Location

  • Once established asparagus can grow and crop for 25 years or more so it’s ideal to plant them in their own garden bed.
  • Plants grow best in a full sun position in soil that holds moisture well, sheltered from wind.
  • Too much shade causes asparagus to become spindly with fewer and thinner spears.
soil TLC tips in summer

Soil

Get the soil right to harvest a bumper crop of yummy asparagus.

Follow our steps for easy soil preparation.

  • Asparagus enjoys well-drained sandy or loamy soil, with pH of around6.5 to 7.0.
  • Prepare the soil prior to planting by digging in well-rotted manure and compost or apply Seasol Liquid Compost.
  • Some growers recommend planting asparagus into a trench with a layer of well-rotted manure in its base. Cover manure with a 5cm layer of soil to keep asparagus out of direct contact with manure.
  • A soil rich in nutrients helps build strong plants so add Seasol Plant + Soil Booster (100g per m2) and a fertiliser such as PowerFeed Controlled Release Tomatoes & Vegetables.
  • Water in well and let the soil rest for a week or two if possible.

Step 1 – Planting from seeds.

  • Fill a pot or seed tray with potting mix or seed raising mix and sprinkle with asparagus seeds over the top.
  • Cover the seeds with mix and water in with Seasol or Seasol GOLD for fast germination.
  • Pop the the pot or tray in a sheltered position, keep the soil moist and protect from pests like snails and birds.
  • When the seedlings are about 10-12cm high, plant them in well-prepared soil as above. Take care not to disturb the roots.
  • Every two weeks apply PowerFeed PRO SERIES for Tomatoes and Vegetables for strong, healthy growth.

Step 2 – Planting from crowns.

  • Plant crowns in winter, burying them in the base of a 30cm-deep trench.
  • Alternatively dig a hole for each crown that’s about 30cm deep and wide enough to accommodate the crown’s root system.
  • Space crowns about 45cm apart then cover with about 5-10cm of soil. As the crown begins to grow, cover it with more soil until the trench is filled to encourage deep roots.
  • Apply a layer of mulch to protect them from cold and frost and once growth appears water them in with Seasol or Seasol GOLD for a strong root development and healthy growth.

Step 3 – Planting potted plants.

  • To plant potted plants, simply dig a hole in well-prepared soil that’s large enough to accommodate the root system. Plant so the base of the plant is well covered with soil.
  • Make a shallow depression around the plant to capture run-off and help to keep the plant well watered.
  • Water in with Seasol or Seasol GOLD to reduce transplant shock and aid plant establishment and mulch around the plant.
  • Apply a liquid fertiliser such as PowerFeed PRO Series for Tomatoes & Vegetables every couple of weeks to promote strong, robust growth and thick stems.

Step 4 – First years growth.

  • Choose only male asparagus plants for cultivation (see notes on male and female plants).
  • Shoots (spears) appear in spring but don’t plan to eat fresh asparagus just yet. Leave shoots to grow to help form strong roots for good future crops.
  • Over spring and summer check soil moisture daily and apply Seasol and PowerFeed PRO Series for Tomatoes & Vegetables every two weeks for strong, vigorous growth and to reduce stress from heat and drought.
  • Hold off harvesting for the first two years and apply organic mulch to keep soil cool.
  • Keep plants well weeded through summer and apply PowerFeed Controlled Release for Tomatoes & Vegetables every 6-8 weeks to ensure strong growth.

Step 5 – Second year’s growth.

  • Plants will start to yellow off in the first autumn after planting.
  • Without harvest, plants produce stems of ferny growth. By autumn the stems will yellow and begin to die back.
  • Stems can be pruned in late autumn as the plants become dormant.
  • If stems are too thin it could be a case of not enough water or nutrients. Check soil moisture and remove weeds by topping up with organic mulch ready for next year’s growth.

Step 6 – Third year’s growth.

  • At the end of winter start to prepare for the first spring harvest and the formation of long spears by hilling soil over the rows.
  • Watch for the spears to appear and harvest the thickest. Leave the rest to mature as ferny growth.
  • In cool areas, produce an autumn crop by cutting mature growth to ground level in late summer.
  • Spears appear from August until September (or later in cool climates) and can be harvested for up to 10 to 12 weeks from well-established plants.

Step 7 – Asparagus harvest.

  • Expect to harvest spears every two to three days from each plant during peak the peak growing season.
  • Use a long, sharp knife to harvest asparagus spears cutting below ground once the spears protrude 10-15cm above the soil.
  • Cut spears each day as they’ll quickly become tall and woody.
  • After harvest, feed with PowerFeed Controlled Release Plant Food Tomatoes & Vegetables for strong ferny growth that feeds the crown.
  • Keep plants well-watered (especially if summers are dry) and free of weeds.
  • Yellowing leaves in late summer and autumn indicate that plants are dying back. Cut plants back to ground level. Regrowth and harvesting will begin again in late winter and spring.

Things to watch for…

Well grown, asparagus has few pests or disease problems. Problems that can occur include:

  • Thin stems These indicate a lack of nutrients or water. Improve spear quality by applying a complete fertiliser, adding a mulch of rotted manure and increasing the amount and frequency of water.
  • Poor soil drainage In heavy clay soil grow asparagus in raised beds to avoid problems with water logging or root rot.
  • Over watering If plants and leaves are yellow it could be a sign they are being over watered. Refrain from watering and check soil before applying more.

Male and female plants

  • Female plants have thin stems and form green berries that ripen to red berries in late summer.
  • Male plants have thicker stems and don’t form berries. They are selected for cultivation.
  • If asparagus is raised from seed, both male and female plants will grow. Cull female plants after their first flowering and allow male plants to grow for a better crop.

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