In Peterborough, plant garlic cloves Oct 10 to Oct 17: one to two weeks after Peterborough's average first fall frost of Oct 3, the timing University of Minnesota Extension recommends. Harvest is usually around Aug 6 next summer.
Why plant garlic in fall
Garlic needs a cold period to start growing, which is why it is planted in fall and harvested the following summer. Fall planting gives the cloves time to grow roots before the ground freezes, and the plants take off quickly once the soil warms in spring.
When to plant garlic in Peterborough
University of Minnesota Extension advises planting cloves one to two weeks after the first killing frost. Peterborough's average first fall frost is Oct 3, which puts planting at Oct 10 to Oct 17. Penn State Extension puts it another way: about three weeks before the ground freezes, so the roots can grow but the shoots stay below the surface until spring.
Timing matters in both directions. Planted too early, shoots can come up before winter and be damaged by the cold. Planted too late, cloves may not root well enough to survive the winter. The frost date is an average, so if your first hard frost comes early or late this year, move planting with it.
Hardneck or softneck
In cold climates, hardneck types are the usual choice. Common hardneck types are Rocambole, Purple Stripe and Porcelain. Hardneck garlic grows a curly flower stalk, the scape, in early summer. Grocery store garlic is mostly softneck, often grown in milder climates, and is not recommended for planting. Buy cloves from a garlic seed grower instead.
How to plant garlic
Split the bulb into cloves a day or two before planting. Plant each clove pointed end up, with its base 5 to 8 cm (2 to 3 in) below the surface, about 15 cm (6 in) apart. Penn State Extension gives a range of 10 to 20 cm (4 to 8 in) between cloves.
Mulch for winter
Cover the bed with 8 to 10 cm (3 to 4 in) of straw or shredded leaves. Mulch evens out soil temperatures through winter and early spring and keeps weeds down. In spring, once the threat of hard freezes is over, pull it back so the soil can warm, or leave it in place to hold moisture. GrowSmart's plan reminds you to pull back the mulch around May 7.
When to harvest garlic in Peterborough
Begin harvesting when the lower leaves turn brown and about half of the upper leaves are still green. In Peterborough, GrowSmart schedules the harvest check around Aug 6, about 12 weeks after the average last spring frost of May 14. Go by the leaves rather than the calendar: a cool spring makes it later, a warm one earlier.
On hardneck garlic, cut the scapes just after they start to curl; GrowSmart reminds you around Jul 9. Left on the plant, scapes can cut bulb yields by as much as 30%. After harvest, cure the plants in a warm, dry, airy place for 3 to 4 weeks before storing.