hi Loretta, it is not necessarily dandruff, it could just be that you have dry skin. i use jojoba oil but you can use olive or almond, any really they are just much heavier. rosemary is very good for circulation, if you have high blood pressure, you can still use it but in a very low dilution. it only usually affects blood pressure when used in high doses regularly. that aside, you could use some essential oils in the base oil like lavender, geranium, virginian cedarwood, sandalwood, bay laurel, rose absolute or just the plain vege oil. all of these oils are good for the hair and the scalp.
if you mix essential oils i use 20mls base oil to 5 drops essential oils which is about a 1% dilution. leave it on for 10 mins or so then wash hair before you wet it, then rinse and wash again. be prepared to have to wash again the next day but i find it really helps if you do this at least once a week.
comb it all through your hair, it is very good for it. hope this helps. lol 🙂