Where can I buy seeds of old varieties of vegetables?

Agricultural seed companies, farmers' markets.

1. Many agricultural seed companies specialize in providing all kinds of vegetable seeds, including some traditional and old varieties. You can search online or contact local agricultural seed companies to find out the kinds of seeds they provide and buy the old varieties of vegetable seeds you are interested in.

2. Many farmers' markets or agricultural products trading markets have farmers or growers selling their own vegetable seeds. You can find some traditional old vegetable seeds in these markets and buy them directly.