The only seed-starting method many gardeners will use, Jiffypots revolutionized gardening and continue to be one of the most popular ways of growing from seed for transplant into the garden. The principle is simple: Jiffypots are constructed entirely of lightweight, sturdy Canadian sphagnum ("peat moss"), so as the roots develop, they eventually grow right through the Jiffypots wall and into the garden soil. It's been working like a charm for decades.
Jiffypots are great for annuals, perennials, and vegetables, and are especially effective for hard-to-transplant species. Because you plant the entire pot without disturbing the root system, many plants which normally suffer transplant shock make the transition without turning a leaf.
