Getting Started

Seeds, Sets or Plants?

Seeds, Sets or Plants?
Onions are one of the most versatile vegetables to grow, able to choose which method best suits your needs. There are many varieties to review when growing from seed with flexible sowing times.

Sets do have less varieties to choose from but are easier to grow having removed the seed growing stages. When working your growing in and around your daily life, it can be quite an advantage to have the benefit of choice dependent on your own requirements.

Growing Onions From Seed


  • Many varieties to choose from
  • Less prone to bolting
  • Flexible sowing times
  • Good to store
  • Can be sown direct into their final positions
  • Most economical way to grow onions


  • More labour intensive
  • Longer growing season
  • Flexible sowing times
  • More susceptible to pests and diseases
  • Longer growing season means it takes longer to reach end goal

Growing Onions From Sets (Small, dry, dormant onion bulbs grown from the previous year.)


  • Easier to plant
  • Easier to grow than seeds or plants, maturing in as little as 3 months
  • Less susceptible to disease
  • Instant gratification


  • Fewer varieties to choose from
  • More prone to bolting – unless using heat treated varieties
  • Not as cost effective as seed

Growing Onions From Plants (Small seedlings)


  • Require about 2 months to reach maturity
  • Less labour intensive than seed


  • Not as cost effective as seed


Onions grow the green top growth in cool weather and form bulbs in warm weather. Therefore, temperature and day length affect / control the timing of the bulb forming. Onions will be slow to grow and more likely to go to seed if temps linger in the 30°C bracket.

Garden / Site:

Onions prefer loose, well drained sandy soil. Turn the soil to at least 8inches prior to bulb planting giving a general fertiliser such as fish, blood and bone or our own specific bulb fertiliser.

When to sow:

Indoors 8-12 weeks prior to the last frosts = End Feb although traditionally Boxing Day is known to be the first day.

Outdoors 1/2" deep 1" apart. 2 weeks prior to last frost in spring = mid May or 4 weeks prior to last frost in autumn.

Avoid sowing until soil reaches 10°C.


Onions are heavy feeders. Blood, fish and bone or onion fertiliser is recommended prior to planting and during the growing season. Avoid direct contact with roots to avoid scorching.

Heat Treated Onions:

A natural process which takes several months meaning rapid and high yields with no risk of bolting (running to seed). Heat treated onions should not be planted before March / April.

Reading next

Getting StartedPricking Out Your Seedlings
The Fruit GardenReceiving Your Fruit Trees