While there is debate on whether organic food is safer, more nutritious, or tastes better than conventionally grown products, if your primary reason for buying organic is that you want to do your part to lessen the impact farming has on the environment, you’re doing the right thing. Much research has found the practices used by organic farming cause less harm to the environment than non-organic practices (although things aren’t as clear on organic meat production).

But buying organic means paying a lot more for food. The market basket we used to shop local grocery chains and stores included 25 fresh produce and 33 meat and dairy products. When we survey stores for their prices for produce, meat, and many of our dairy items at grocery stores, we seek the lowest-priced items available, which often are non-organic products. But when we looked for organic-only options, we found striking price differences: Overall, organic products cost 80 percent more than their non-organic counterparts.

The figure below indicates how the Washington area chains and stores we surveyed compare for their prices for organic produce, meat, and dairy products. The $83 score in the produce column for Whole Foods means that its prices at the store we surveyed for organic produce were about 17 percent cheaper than the average prices for the comparable organic produce items at all stores we surveyed. The $110 score for Giant means that its prices for organic produce were about 10 percent higher than average.

As you can see, the organic-price penalty is bigger at some stores than at others. For produce, Lidl, Food Lion, and Walmart, which offered low prices for non-organic items, also offered low prices for organic options. Trader Joe’s and Whole Foods’ prices for organic produce were also quite a bit lower than what we found at many other local chains. For organic meat and dairy products, however, Whole Foods’ prices were about the same as the average prices found at all surveyed stores.

Keep in mind that some companies clearly have higher buying standards than others, as indicated by the huge chain-to-chain differences we found when we surveyed area grocery shoppers. Surveyed customers of MOM’s Organic Market, which sells only organic products, gave it very high marks for the quality of its produce, and its prices for organic produce were about 13 percent higher than average—but only slightly higher than prices at Giant, Shoppers, or Safeway. On the other hand, Wegmans offers both high quality and low prices for organics: Its prices for organic produce, meat, and dairy were lower than average, and area consumers rated it highest for produce and meat quality in our survey.

Some stores carried too few organic items for us to include them in our comparisons. ALDI, ShopRite, and Target offered very few organic alternatives at the locations we shopped—too few to include in our comparisons of organic costs.

Know that while buying and eating organic likely does lessen the impact of agriculture on the environment, the most environmentally friendly approach is probably to eat less meat (or none); minimize purchases of highly processed and packaged food; as much as possible eat what’s in season; and whenever possible buy products grown or raised locally that didn’t have to be shipped a long distance.

Want info on locally grown food sources? The nonprofit LocalHarvest.org offers a fantastic online database of searchable listings of farmers’ markets, CSAs, farm stands, groceries, and restaurants.