Time to plant
Onions: Temperature plays an important role in
the development of onion bulbs. However, in order to
initiate bulb formation, day length is more critical.
Each onion variety has a critical day length for inducement
of bulbing regardless of temperature or plant size. Short-day
onions require day lengths of 12 to 14 hours. Long-day
varieties require 14 to 16 hours of day length. Growing
onions at less than critical day length results in formation
of new leaves but no bulbing. When short-day onions are
grown under long-day conditions, bulbing develops while
the plants are very small and results in small bulbs
(great for cocktail onions).
Garlic: Garlic is generally best planted in the fall for largest size bulbs at harvest. Later planting
is acceptable but bulb size may be smaller. Bulb formation begins in response to lengthening days.
In cold-winter areas, mulches around the plants will protect them from severe cold.
Garlic and onions are suitable for a small garden if
compact varieties are grown. In a suitable climate, green
onions may be planted more than once a year for a continuous
*Areas are large, so planting dates are only approximate,
as the climate may vary even in small sections of the
state. Contact experienced gardeners in your community
and experiment on your own to find more precise dates.
Dates for Onions and Garlic*
||Transplant or direct
North and North Coast
Monterey County north
Jan. - Mar.
San Luis Obispo County south
Sacramento, San Joaquin valleys
Imperial and Coachella valleys