I personally don't suffer from an itchy scalp, but apparently a lot Naturally Obsessed readers are struggling with this issue. I found an informative article, written by Amy O'Conner at FindArticles.com, that breaks down the causes of having a dry scalp and she offers some good solutions as well.  Here's a snippet of the article...

Dry Scalp, characterized by itching and sometimes, dry flakes (not dandruff-like clumps), can be caused by genetics or harsh shampoos; in the latter case, the damage can be offset by switching to a plant-based, pH-balanced product. Shampooing hair more than once a day also leads to problems. "People who exercise a lot need to cleanse more often, but they shouldn't shampoo more than once a day--just rinse," says Hamernik. And when you shower, turn down the water temperature. While hot water might be soothing, it can exacerbate a dry scalp problem. "Most of us use excessively hot water, which means you're no longer hydrating, you're dehydrating," she explains.

One of the best ways to treat dry scalp flakiness is with an essential oil, though oily scalps also can benefit. Lazo recommends massaging a few drops into the scalp for five minutes or longer before shampooing. Jojoba oil, which smells fresh and fruity and has a non greasy feel, is "the most effective for breaking up encrusted oil and pollution and helps to break up flakes so that they're easier to remove during shampooing," Hamernik says.

Tea tree oil, a natural antiseptic that combats bacteria and soothes irritated skin, has a strong disinfectant smell, so look for hair products that contain it if you don't want to apply it in its pure form. A good one for normal to dry hair is Desert Essence's Daily Replenishing Conditioner with tea tree oil and jojoba. To ease the itchiness often associated with dry scalp, apply cooling eucalyptus oil. Essential oil of sage moisturizes and soothes very dry hair and a scalp that's been damaged by over processing. To use either of these essential oils, just warm a few drops in your palm, massage them into your hair, wrap head with a warm towel for 10 minutes or longer and then shampoo. A dry, itchy scalp is a bigger problem in winter and may need extra conditioning and essential oil treatments when the air tends to be drier.

The full article adresses other scalp conditions as well, click here to view them.