There are a lot of reasons your scalp could be dry, and even the best dry scalp treatments will only help if you first identify the cause. That's why there are a number of factors to consider before you invest in a scalp treatment.
While dryness could mean your scalp isn't getting enough moisture, there are a lot of other things (like dandruff) that can appear to be dryness. A good indicator of a truly dry scalp is if the rest of your skin is lacking in moisture and if the dead skin that flakes off is also dry. Dandruff, on the other hand, will produce oily flakes, and the scalp will often be red or scaly where it's flaking. Chronic skin conditions like psoriasis and eczema can also cause a dry scalp, resulting in inflamed, red flaky patches of skin on and around your scalp. Any of these issues can lead to a dry scalp, but they warrant different treatments.
If you think your dry scalp is more than just dryness or mild dandruff, don't try to self-diagnose: Consult a dermatologist. Once the problem is identified, you'll have an easier time finding the right treatment for you. From there, I suggest starting with one these six tried and true treatments for dry scalp.