14 tips for getting a great asparagus crop in New Zealand: How to plant asparagus crowns

Planting asparagus crowns all comes down to technique.

1. Asparagus crowns can be planted in August in rich, sandy, well-drained soil in full sun.

2. Avoid sites that retain pools of water after heavy rain, or the crowns will rot. If in doubt, plant in raised beds that have a depth of at least 25cm.

3. If you live in an area of hot summers, a partly-shaded spot where the soil stays cooler is beneficial.

4. Add coarse sand for better drainage.

5. For successful cropping, good soil preparation is essential. Anything you can do to raise the organic matter will pay enormous dividends. Compost and aged manure is ideal. Add the organic matter and dig your soil over to a depth of 20cm to make it loose and friable.

6. For a family of four asparagus lovers, 25 crowns will produce 4-6 spears per person every day in the picking season.

7. Each crown should be planted about 40cm apart, or one 10m-long row.

8. When it comes to planting, dig a trench 15cm deep. Throw in some phosphate fertiliser, which is beneficial for root growth, especially during the plant’s establishment. Plant your crowns, then backfill the trenches without compacting the soil.

9. An occasional feed with a dilute seaweed tea can be beneficial while crowns are establishing, otherwise sit back and relax.

10. It’s essential that you don’t pick any spears in the first year otherwise you can weaken your plants. Let the spears open up into the feathery fern stage. While they’re still green, they are feeding their crowns and strong crowns are the secret to success. In the second year, only harvest a few spears to enable the crowns to continue building up strength.

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11. Proper harvesting can begin in the third year. Pick spears once they’re about 15-20cm long and before the tips open up. Cut them with a sharp knife at ground level.

12. Pick daily or spears will become tough. Harvesting runs for 6-8 weeks.

13. When cropping begins to slow down and the spears thin down (less than 1cm in diameter), stop picking altogether. You will still have spears, but resist the temptation to pick them. These are best left on the plant to replenish nutrients to the crowns.

14. Apply a layer of compost around your plants and leave them be. Don’t cut back the ferny fronds until they begin to die back. Your signal for doing this is when they start to turn yellow in autumn or early winter. Cut them back, then add another layer of compost and feed with liquid seaweed, or cover with a mulch of seaweed gathered from a nearby beach.


NZ Lifestyle Block This article first appeared in NZ Lifestyle Block Magazine.
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