Vegetable collections offer gardeners a way to grow a variety of vegetables at an economical price. You can choose from several collections, including pepper, sweet potato, tomato and onion seed collections. When considering what vegetable collections to buy, take into account your hardiness or grow zone as well as the plants' light and soil requirements for optimal growth. Most vegetable plants grow best when planted in full sun and well-drained soil, rich in organic matter. Also, determine how much space the collection will need in your garden. You can do this by taking into account the plants' mature heights and spreads and how many items are included in the collection. If you don't have quite enough garden space for an entire collection, consider sharing with a friend.