All types of leeks (a member of the onion family) do well in our zone 7 as long as the soil is rich and drains well. Leeks can be planted in early spring if you find the small bulbs or offsets for sale. Otherwise plant seeds in the late summer and they will be ready to harvest the following summer. Kohlrabi will mature in our cool summer climate only if you grow it in full sun. Don't plant the seeds of the heat-loving Kohlrabi until the soil is warm in mid June. Sounds like you will enjoy lots of veggies this summer. Keep growing, Marianne Binetti