How To Water Garlic Plants
How Much Water
Garlic plants like to have a consistent supply of moisture throughout the growing season. In general, this means about 1 inch of rain or irrigation per week on clay or loam soils and up to 2 inches on sandy soils during the warmer parts of the growing season.
Not supplying enough moisture can lead to stressed plants that produce much smaller bulbs at harvest (although they will usually be flavorful and store well). Drought stress for even a few days can trigger garlic to produce smaller bulbs.
On heavy clay soils, it is best to lean towards watering slightly less whereas on sandy soils it is hard to overwater if the watering is spaced out and managed properly.
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Time of Day
The best time of day for watering is during the morning or mid-afternoon. This allows enough time for the plant foliage to dry before cooler temperatures arrive in the evening.
During extremely hot periods watering during the day when temperatures are hottest can also help with cooling the canopy and improve growing conditions. This can help minimize stress on the plants that might promote early maturation and therefore smaller bulbs.
Reducing Water Preharvest
Watering should be stopped once the garlic has matured and it is almost time to harvest. Usually this means no longer watering one week to 10 days before the garlic is dug up from the soil. This will help promote drying of the plants and curing of the bulbs, which is a natural process where the dry conditions send a signal to the garlic plants for them to start the final stages of growth and begin to move towards dormancy.
Dry conditions also help with the harvesting process and improve the condition of the bulb wrappers by reducing their deterioration. This produces better quality bulbs that will store longer and have better marketability for those who sell their garlic.
How We Do It
On our farm, we rely on rainfall and sprinkler irrigation to water our garlic. Being located in the middle of North America and on the edge of both a "dry" western climate and "wet" eastern climate, we can sometimes have substantial rainfall throughout the summer and sometimes have none at all for the whole season.
When watering is needed, we lean on the side of less water on our clay soils and more water on our sandy soils. We try to irrigate only when conditions are hot and dry (usually late June and early July). In early spring we mostly rely on the moisture stored in the soil from the winter.