[Tilted Irish Kilt]

greeneyes:"..there is at least 4 years in between the times that tomatoes are planted."

The 4 year cycle rotation is the ideal agricultural practice .
Even the seed stores here have dandelion (sp ?) seed since the roots go down as deep as 15 feet into the subsoil
and draw up micro-nutrients back up into the topsoil .
That is the ideal if you have adequate room for a large garden.
If you don't have much gardening room , you should still rotate "families " of crops to minimize disease and maximize productvity,
or keep a chart of which crops you grew where , so as to keep the soil in rotation.

[greeneyes]

That’s right. Even the smallest spaces are rotated. We let the dandelions grow as rampant as they want in our yard. After all, they are one of the earliest sources of Vitamin C in the spring.

We have mullein which grows in the wild, and Hubby has been letting several of those grow too as they are supposed to bring up lots of nutrients from below.

[Tilted Irish Kilt]

Vegetable families , and crop rotation
Best chart and worthy of printing out:
http://www.organicsforall.org/vegetables.htm FAMILY VEGETABLES in FAMILY
Amaryllidaceae: chives, garlic, leeks, onion
Brassicaceae: horseradish, mustard, broccoli, Brussels sprouts, cabbage, collards, cauliflower, kale, kohlrabi, radish, watercress
Chenopodiaceae: beet, Swiss chard, spinach
Compositae :endive, escarole, cardoon, artichoke, sunflower, lettuce, salsify
Cucurbitaceae: gourd, melon, squash, cucumber, luffa
Gramineae: corn
Solanaceae :tomato, pepper, eggplant, potato, tomatillo
Umbelliferae: celery, carrot, dill, chervil, cilantro, parsley, fennel, parsnip
Convolvulaceae (sweet potato),
Labiateae (basil),
Malvaceae (okra),
and Polygonaceae (rhubarb, sorrel).