ST. HELENS, Ore. — Fertilize garlic in the spring if you want a large and healthy crop of bulbs by summer, advises Chip Bubl, garlic expert and agricultural agent at the Columbia County office of the Oregon State University Extension Service in St. Helens.
If you planted garlic in the fall, by springtime it will be ready for either a side dressing of fertilizer or a broadcast application over the entire bed. (October is the best month to plant garlic in most places in Oregon.) "High-nitrogen organic fertilizers such as bloodmeal or a synthetic source of nitrogen are best," Bubl said.
Fertilize garlic again just before the bulbs begin to swell in response to lengthening daylight (usually mid-May).
Keep garlic well weeded, as it cannot stand much competition. As the spring weather dries out, water garlic to a depth of two feet every eight to 10 days if needed. Many years, there is enough soil moisture from spring rains that no watering is needed. Very sandy soils are the most likely candidates for watering. As mid-June approaches, taper off on the watering.
"Don't wait for garlic leaves to start to die back to check for maturity," Bubl said. "Sometimes the bulbs will be ready to harvest when the leaves are still green."
The best way to know if garlic is ready to pull from the ground is to pull one up and cut it open cross-wise. Then look for well-developed cloves and three or fewer outer "skins" or covering layers over the bulb. Or dig a representative bulb, pull the cloves apart and count the skins as you go.
Start checking for mature cloves about late June, Bubl suggested. Harvest garlic when the head is divided into plump cloves and the skin covering the outside of the bulbs is thick, dry and papery.
"If left in the ground too long, the bulbs sometimes split apart and become difficult to harvest as intact heads," Bubl said. "The skin may also split, exposing the cloves, which will cause them not to store well. In addition, unseasonable rains or irrigation in late June or July can aggravate some garlic diseases."
Dig, and then dry the mature bulbs in a shady, warm, dry and well-ventilated area for a few days or longer. Garlic dried without shade can sunburn, leading to inedible cloves. Then remove the tops and roots. Brush dirt off the bulbs. To braid garlic together, harvest it a bit earlier while leaves are green and supple. Avoid bruising the garlic, as it will not store well.
Store bulbs in a dark, dry, well-ventilated place. Protect from high humidity and freezing. The refrigerator is not the place to store garlic. Cool temperatures stimulate sprouting.
The publication "Garlic for the Home Garden," FS 138, is available free online, or order a printed copy for $1 plus shipping and handling by calling 800-561-6719.