There is no commonly accepted definition of what is an heirloom seed. Generally, they have to be an old well-established variety, but how old?
The definition we adhere to for an heirloom variety is that they have to be at least 50 years old, they must be open-pollinated, and they must never have been genetically modified. Open-pollinated means that they breed true, or that seeds saved from a specific variety will grow into plants of the same variety. Modern hybrid varieties typically produce seeds that do not breed true, you will not get the same exact same variety of plants if you save seeds from them.
We carry a handful of varieties that we call open-pollinated as opposed to heirlooms. The only difference between these and heirlooms is that they are not yet 50 years old. They are still open-pollinated and non-genetically modified.
Organic seeds are seeds from any variety that have been raised in an organic manner. In order to be labeled organic, they have to have been raised on a farm that passes certain government standards for pesticide and fertilizer use, etc. Organic seeds could be old-style heirloom varieties or modern hybrid varieties. The only requirement is that they pass the government “test” for organic labeling.
It is our opinion that it is far more important for you to use organic practices in your garden where you grow your vegetables than it is for you to start with organic seeds. Organic practices used in producing the seed have little to do with creating a plant that produces healthy fruit. However, proper manuring of your garden, using pesticides that minimize impact to friendly inspects and are not poisonous to humans and animals, these are organic practices that have a major impact on the quality of the produce you grow. Our recommendation is to find good quality heirloom varieties, and grow them in an organic manner to maximize the taste the healthiness of your produce. Starting with organic seeds certainly can’t hurt, but I don’t think it makes a big impact.