Gardening Plant diseases Vegetables

Why Are My Tomatoes Green Inside?

Tomatoes cut open with some green inside.

By Larry Hodgson

Question: I just harvested my first tomatoes and discovered the inside was still greenish. Is this normal? Are they still edible? This is my first time growing tomatoes and, in fact, growing vegetables of any kind!

F. Martin

Answer: There are many possible reasons as to why certain tomatoes retain a bit of green tissue inside their fruit. 

To start with, this is quite normal for certain tomato varieties. This especially true of heritage tomatoes, some of which, like ‘Everett’s Rusty Oxheart’ and ‘Thorburn’s Terra Cotta’, tend to have quite a bit of green inside, even when grown under perfect conditions. In fact, there are tomatoes that are green through and through even at full maturity, such as ‘Aunt Gertie’s German Green’ and ‘Green Zebra’. Green inside or not, such tomatoes will be perfectly edible and delicious.

Possible Problems

In other cases, though, green flesh inside the fruit indicates a problem. 

Tomatoes usually mature from the inside out, so are usually quite red inside even before the outside has taken on its final coloration. However, maturation doesn’t always go smoothly. Stresses of various sorts can cause the fruit to mature unequally. The problem can be due to:

  • Immature fruit: yours might not have been quite as ripe as you thought. A few days more “on the vine” might allow them to redden up inside.
  • A long period of drought, especially when followed by a heavy rain, can lead to fruits that don’t turn fully green;
  • Excessively hot weather, especially temperatures over 90˚F (32˚C), can have all sorts of effects on tomato fruits, including unequal maturation;
  • Cool nights (temperatures below 55˚F/13˚C) can also lead to unequal maturation in some varieties;
  • There could be a mineral deficiency (a lack of potassium, for example), so it may be wise to fertilize with a complete fertilizer—in other words, one that contains the whole range of major and minor minerals, like hydrolyzed fish or seaweed fertilizer—, just to be sure;
  • Compacted or overly wet soil can prevent nutrient uptake and lead to unequal maturation;
  • Removal of too many leaves for whatever reason can be a cause. Some people remove leaves from their tomatoes “to stimulate faster maturation,” but not only doesn’t this work, it can have exactly the opposite effect;
  • Insect damage, caused by whiteflies, stink bugs or others piercing the tomato, can leave immature patches inside the fruit at the site of the wound.

The best way to avoid the above problems is simply to give your tomato the best conditions possible. Obviously, you can’t control the weather, but you can make sure your plants are well watered and fertilized, grow in rich, friable soil, are kept a bit cooler by mulching, are treated against insect problems without delay and don’t suffer needlessly due to the removal of healthy green leaves. 

Yes, You Can Eat Them

And don’t worry: even if your tomato are a bit green inside, they’re still edible. 

If they’re perfectly mature, as in the case of a variety that is normally green inside, they should be delicious. Just bite in! 

If you harvested yours a bit early and their greenness comes from not being quite ripe, you’ll still find them very tasty, but perhaps not yet at their best. Try letting them mature a few days longer in a dark cupboard or brown paper bag. Many will ripen perfectly when so treated. 

And if ever yours are just not as flavourful as you think they could have been, try cooking them up and using then in a recipe of some sort rather than eating them fresh. Cooking is a great equalizer when it comes to not-quite-perfect tomatoes! 

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

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