How to Treat an Oily Scalp and Dry Roots
Having an oily scalp and dry roots can be frustrating, but if you choose the right hair products and eat more Vitamin B12, you should notice a change. Look for a shampoo that says "for combination hair" which will help keep your scalp clean without drying out your ends. Use a conditioner designed for dry hair too. Avoid styling products with alcohol in them, since these can be harsh on dry roots. Try to find products with aloe vera in them, or mix some into your shampoo yourself. This will help to treat your dry hair. You should also eat more foods rich in vitamin B12, like fresh meat, fish, eggs, and dark green leafy vegetables. Getting enough B12 should help to reduce the oiliness of your scalp.
Choose the right shampoo for your hair. For as straightforward as it may seem, this task can feel insurmountable when the entire, inscrutable shampoo aisle is looming down upon you. Often, shampoos which treat both an oily scalp and dry hair are marketed "for combination hair." Dandruff commonly co-exists with an oily scalp. If you're also dealing with dandruff , there are several dandruff shampoos available that should be appropriate for you. Don't hesitate to step away from your usual brands if they're no longer getting the job done for you at any point during this process; many find that proper management of their hair requires occasionally, or even routinely, shaking up their shampoo status quo. Select the right conditioner. Although effective 2-in-1 products do exist, use of both shampoo and conditioner is recommended to properly care for your hair. Dealing with both ends of the spectrum (both an oily scalp and dry roots) will be much easier for you when you're able to separately change the amount of shampoo that you use and the amount of conditioner that you use. A telltale visual: conditioners for dry hair are often creamier, and not quite so clear as others. Determine how regularly you should wash. This will vary depending on your hair's thickness, coarseness, and curliness, among other qualities, but every head needs to be rid of the dead skin, dirt, and oils it accumulates. Regularly may mean twice a week, daily, or even every other week. If your scalp is too oily, though, this is because the sebum--that is, the oils and dead skin--that your scalp is producing is not being washed away at proper intervals. But here we come to what seems like a paradox in haircare: because the human body strives to attain homeostasis (the state of remaining the same) if you wash your natural oils away too frequently, your body will actually produce more and more of them. This renders your scalp and hair even oilier due to washing it too frequently, and you were washing it frequently in the first place so that it wouldn't be so oily! Defining "regular" washing will require some experimentation, but if you're washing anywhere close to daily, err on the side of washing less frequently at first. In Western culture, it's been ingrained in many that they need to wash more often than they actually do. If you've been washing your hair often, washing less frequently may leave your hair and scalp oilier than usual for a few days while your body acclimates. Wash your hair. Thoroughly dampen your hair in the shower, then squeeze about a half an inch to an inch (in diameter) of shampoo into your hand. The actual amount will vary depending on the length of your hair. Your shampooing technique should be similar to a gentle scalp massage, followed by thorough rinsing. Bath soap can occasionally be used in place of shampoo. This method, however, should be employed weekly at most, and not repeatedly performed for extended periods of time. Bath soap provides a powerful clean for an oily scalp, but is too harsh on hair to use often. Condition freely. Conditioner should be regularly applied after washing out the shampoo, and followed by another rinse. While the amount of shampoo you use should be very carefully doled out, conditioner can be applied much more liberally to dry hair.  Conditioner is essential to moisturize your dry roots and hair after shampoo washes their natural oils away. Consider dry conditioners if your hair is feeling dry between conditioning sessions. These are sprayed outside the shower on dry hair, then brushed through for a mid-week moisture boost. Comb your hair when it's dry. Combing or brushing your hair distributes its natural oils evenly, which will help combat your oily-scalp-but-dry-roots situation. Brushing while it's dry is preferable to brushing it right when you exit the shower; hair is more elastic when it is wet, and breakages can more easily occur during this time. Massage your scalp. It's part of proper shampooing technique, and it's helpful outside the shower as well. Gentle massage stimulates hair follicles and improves blood flow, generating more of the oils essential to keep your hair healthy. This may feel counterintuitive, prompting your head to make more oils when you're already dealing with an oily scalp. Used in combination with all of these other, proper techniques, however, those oils will be nourishing your dry hair, not sitting around and clogging up your scalp. Mix aloe vera into your shampoo. A few drops are sufficient for this mixture, which you can then use as you would regular shampoo. Many conditioners on the market also include aloe as an ingredient to treat dried-out hair. Has the bonus of being topically soothing for a dandruff sufferer's itchy scalp. Aloe juice or gel can also be combined with lemon juice and applied separately, before shampooing, but it should be noted that lemon juice can have a drying effect on your hair. Whisk up an egg yolk conditioner. There are plenty of different recipes to be found, but a basic one employs two egg yolks, beaten well, with two tablespoons of olive or coconut oil. After beating the two egg yolks together with the oil, apply it to your hair and let it sit for five minutes. Wash your hair thoroughly so that no residue remains. Utilize instead of shampoo according to your wash schedule, alternating egg washes with regular cleanings. Knock back a beer (over your head). Really! After the liquid evaporates, the two ingredients remaining from the beer are malt and hops, proteins which can revitalize your dried out roots. Although some opt for the fun of simply pouring a beer over their head mid-shampooing, you can also mix boiled (but not currently boiling) beer with a mild shampoo and use that in the shower.  This should be incorporated occasionally (it'd get a bit expensive, otherwise), in addition to your normal wash. This will, quite predictably, cause your head to smell like beer; interpret this as positively or as negatively as feels appropriate to you. Dab witch hazel on your head with a cotton ball. The oil will tighten up your blood vessels and act as an astringent, drying out your scalp, so take care to use this more on your scalp than your dry hair. Put down the bottle of bleach. Habitual hair dyeing can take a toll on your hair, especially when bleach is involved. If you regularly dye your hair and continue to have issues with dry roots, consider taking a break from the color regimen. Any heat processes or chemical treatments can have an adverse effect on your hair's health over time. Limit blowdryer and flat iron use if you're having issues with dry roots. Check your hairsprays and pomades for alcohol. Styling products containing alcohol should be avoided if you have dry roots, as it can be harsher on hair. Alcohol has often been added so that the product dries faster after normal use, but it causes the product to function like an astringent on your already too-dry roots.  Care should be taken to work your pomades, gels, mousses, and waxes into only the tips of your hair, if you choose to continue using them. Too much at the base of your follicles near the scalp can exacerbate oiliness. Eat mindfully. Hereditary factors are not alone in deciding the state of your scalp. Deficiencies of riboflavin and vitamin B12 specifically have been shown to have a hand in an oily scalp. Seek out supplements if you're unable to incorporate foods that are richer in these into your diet. Dairy, dark green leafy vegetables, and whole grains provide riboflavin. Meat, poultry, eggs, fish, milk, and cheese are excellent sources of vitamin B12. Change your care with your environment. Humidity can cause scalps to be oilier than usual, in which case you may need to abstain from products, or perhaps even rinse your hair more often. Summer months can over-moisturize hair, whereas winter months will require diligent conditioning to keep your dry roots from getting even drier. When you know you'll be out under the hot, midday sun for any considerable period of time, consider hats or scarves to protect your hair from its moisture-thieving rays. 
Choose the right shampoo for your hair. Select the right conditioner. Determine how regularly you should wash. Wash your hair. Condition freely. Comb your hair when it's dry. Massage your scalp. Mix aloe vera into your shampoo. Whisk up an egg yolk conditioner. Knock back a beer (over your head). Dab witch hazel on your head with a cotton ball. Put down the bottle of bleach. Check your hairsprays and pomades for alcohol. Eat mindfully. Change your care with your environment. 