Yes, leeks survive winter in the garden better than most crops you can grow. Hardy types handle temps down to 20°F (-7°C) without damage when you add mulch. Some gardeners in mild areas harvest fresh leeks from the ground all winter long.
I kept Musselburgh and Bandit leeks in my zone 6 garden through two harsh winters. A thick layer of straw was all I used for cover. The plants stopped growing once temps dropped below freezing. But they stayed alive under the mulch and waited for me to dig them up when I needed them.
Brushing away snow to pull a fresh leek in January became one of my favorite garden tasks. The stems were firm and crisp even after weeks of freezing temps. My neighbors thought I was crazy out there digging in the snow. But those winter leeks tasted better than any I had pulled in fall.
Frost does something great to leek flavor that you cannot copy any other way. Cold temps make the plant turn its stored starches into sugars to survive the freeze. This change makes winter leeks taste much sweeter than fall ones. Many pro chefs look for frost hardy leeks just for this improved taste.
UMN Extension says that cold-hardy types handle temps down to 20°F (-7°C) with no cover at all. Add mulch and they handle even colder weather without trouble. UW Extension notes that leeks keep growing through mild winters in zones 7 and up. This gives you bigger harvests than fall-dug plants would provide.
The key to overwintering leeks is prep work before the ground freezes hard. Put down 4-6 inches (10-15 centimeters) of mulch like straw, leaves, or hay. Do this once night temps start hitting the 20s in your area. This layer keeps the soil from freezing solid and guards the stems from cold wind.
Different types show different levels of leek cold tolerance that shape your success rate. Bandit and Tadorna bred for winter use survive the coldest snaps without damage. King Richard works better for summer harvest and may not last through zone 5 winters. Check the seed packet for winter ratings before you buy seeds or starts.
Pulling overwintered leeks takes some patience when the ground stays frozen solid. Wait for a warm spell when you can work a garden fork into the soil with ease. Take what you need for cooking and put the mulch back over the rest. This method gives you fresh leeks from one planting for up to eight months running from fall through spring.
Read the full article: Growing Leeks: Beginner-Friendly Guide to Sweet Harvests
