A Limestone (as in B-52s, not the granular stuff) gardener wants to know why the carrots from her garden are bitter and those she buys at the store are not.

Flavor in carrots is a two-part story. First, there are compounds called terpenoids which carrots produce, and these hydrocarbons have a resinous, somewhat bitter flavor. (Turpentine is another terpenoid chemical, and if you think about it while eating your next carrot, you can taste the family resemblance). Second, there are sugars produced and stored in carrot roots in varying quantitites depending on variety, growing conditions and time of year.

Put the sugars and terpenoids together in the right proportion, add a little crunch and some beta-carotene, and you have a delectable carrot, my favorite vegetable. If sugars are low, the carrot will be bitter, and if terpenoids are low, the carrot will be bland.

Now, as to the Limestone gardener’s problem, my best guess is that she may be digging her carrots too soon. Most varieties of carrots, if planted in May or early June, will produce good sized roots long before the first frost. But it takes a few frosts to raise the sugar level in almost any carrot variety. So, better to leave the carrots alone until early autumn.

I suppose it might also help to try a new variety or two, and I am quite high on Johnny’s varieties, Rhumba and Ingot. Both are super-delicious, and the latter also impressed me because it pulls more easily than any other carrot I have grown. Their new catalog will be out before long. To obtain one, write Johnny’s Selected Seeds, Foss Hill Road, Albion 04910.

Continuing the theme of flavor development in vegetables and fruits, here are some tips and observations that might be of interest.

Brussels sprouts are perhaps the most controversial of all vegetables. Most people and almost all children have a very disdainful opinion of B. sprouts’ flavor, and small wonder since the typical commercially grown, machine-harvested sprout is a powerhouse of insipid cole crop flavor. But if you were to grow the variety, Prince Marvel (available from many seed houses including Stokes Seeds, P.O. Box 548, Buffalo, NY 14240), and if you were to leave it in the garden until mid-November, you would discover why the English eat more sprouts than the rest of Europe combined.

Winter squash are apt to rouse some fierce feelings among the hungry populace. As a child, I felt that acorn and butternut squash were put on earth to make small people come very close to throwing up at the dinner table. In fact, if I eat either of those varieites now, a certain queasiness still comes over me. But a good buttercup squash is quite another matter, and for some reason this year’s crop of buttercups is absolutely superb. Even our teen-aged son comments on how tasty this less-than-favorite of his vegetables is this year.

Finally, a few words about apples. Our little farmlet is blessed with an old orchard. There are three trees of the original strain of McIntosh, and three of the original red delicious. In the decades since these two were introduced, they have been reselected several times for improved color, higher yield, better storing quality and almost any other commercial consideration you might imagine, except flavor.

Did you ever wonder why red delicious is called that? I did — every time I bit into one of those glossy, bumpy West Coast fruits that look so appealing in the produce department. Now I know the answer. The old-fashioned red delicious, if left on the tree until Halloween or later, develops a condition called water-core, in which the center of the fruit goes translucent and juicy without becoming mushy. After a time the juice begins to ferment and the flavor becomes just plain delicious.

If you notice a common thread in all these observations, it is that home-grown produce is generally more flavorful than that which mechanized agriculture can provide us with. So why not plant a garden or make your current garden a little bigger?

Michael Zuck of Bangor is a horticulturist and the NEWS’ garden columnist. Send inquiries to him at 2106 Essex St., Bangor, Maine 04401.