Onions Flashcards

1
Q

What are the temperature preferences of onions?

A
  • 13-24C
  • Many are frost tolerant and can overwinter outside
  • There are two main types, autumn and spring.
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2
Q

Explain the soil and site selection for onions.

A
  • Open, sunny site
  • Well-drained, fertile soil
  • Prepare well in advance, digging over and incorporating plenty of well-rotted organic matter
  • Do not like freshly manured ground
  • Low nitrogen requirements.
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3
Q

What are the two times for sowing and harvesting onions?

A
  • Spring sown are harvest in late summer (take 12-18 weeks to mature)
  • Autumn sown are planted in late summer or early autumn, overwinter outside, and take up to 42 weeks to mature.
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4
Q

Explain sowing of onion seeds.

A
  • Secondary cultivation of soil two weeks before sowing
  • V-shaped drill, 13mm deep
  • Rows 30cm apart
  • Once germinated, thin to 5cm apart.
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5
Q

What are onion sets?

A

Specially raised small onions ready for planting out.

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6
Q

What are the advantages and disadvantages of onions from sets and seeds?

A

Sets

  • Mature before those from seed
  • More resistant to mildew and onion fly
  • Tend to bolt
  • More expensive than seeds.

Seeds

  • Take longer to mature than sets
  • More susceptible to mildew and onion fly
  • Less likely to bolt
  • More cultivars to choose from
  • Cheaper option than sets.
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7
Q

Explain sowing spring-sown onions from sets.

A
  • Plant sets in well-prepared seedbed in April
  • Place so nose is just above ground
  • Space sets 30cm apart
  • Cover with mesh to avoid birds pulling them up
  • Weed regularly.
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8
Q

Explain the harvesting of onions

A
  • Onions can be harvested at any time once they’re ready.
  • If you’re storing them, let the foliage die down naturally.
  • Spring sown onions keep better than autumn sown ones.
  • Once ripened, lift and dry for storing (plait or place in single layers in wooden boxes and store in a dry shed).
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9
Q

Name a pest and a disease of onions, including symptoms and control methods.

A

Onion Fly

  • White burrowing larvae eats bulbs
  • Yellowing leaves, tunnels in bulbs, death of plant
  • Place collars around plants in May and August; Grow sets instead of seeds; Destroy infected plants; Grow resistant cultivars; fleecing.

Onion White Rot

  • Fungal disease that can last in soil for 15 years
  • Plants suddenly die, leaves yellow, roots rot off; white cottony-looking fungal growth with black poppy seed-like sclerotia at base and sides of bulb
  • Grow from sets rather than seeds; buy from reputable source; use long rotation and avoid infected ground for at least 8 years; grow resistant cultivars; good hygiene.
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10
Q

Name:

  • 2 autumn seed onions
  • 2 autumn sets
  • 2 spring seed onions
  • 2 spring sets
A

Autumn Seeds

  • ‘Senshu Yellow’
  • ‘Keepwell’ F1

Autumn Sets

  • ‘Radar’
  • ‘Autumn Gold Improved’

Spring Seeds

  • ‘Caribo’
  • ‘Red Baron’

Spring Sets

  • ‘Sturton’
  • ‘Stuttgarter Giant’.
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