Why are my asparagus spears very thin?


Hi Tui, our asparagus is very thin and grows tall quickly. How do we remedy the problem? Thanks.



Hi Lesley, asparagus crowns can keep producing for 25+ years. If your plants are newly planted then in the first year only harvest one meal from the patch and leave it to go to fern. In the second year, harvest two meals, then let the bed go to fern. In the third year, take three meals and let it go to fern. In the fourth season and successive seasons, harvest spears for 6-8 weeks until the spears start becoming sporadic and let the bed go to fern each season. Keep the bed weed free, apply compost to replenish the soil each season and feed with a nitrogen rich fertiliser such as Tui Blood and Bone. Cut the ferns down when they are yellow, the green fern is the food source for the crown the following season. Each crown should produce approximately 25 spears each season.

There are several reasons your asparagus are thin and go to fern quickly. It could be you have mainly female plants in your patch. You can tell male and female plants apart when they flower. Both have creamy white/yellow flowers. Male plants have yellow and orange stamens inside the flower, the flowers are bell shaped. The female flowers have a green ovary inside the flower, these become berries in autumn and winter. Male plants produce higher yields, thicker spears and usually earlier than female plants. Female plants can be removed and discarded. Another reason is over-harvesting, not leaving enough fern fronds to build up food reserves in the crown for the following season. Lack of fertiliser can be a cause, feed asparagus with a nitrogen rich fertiliser and apply compost each season after the fern frond is cut down. Not enough sun on the asparagus patch can cause spindly spears. The Tui Team.

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