Using chemical and ammonia based liquid hair dye is dangerous for scalp and hair health.
You will lose hair quicker than normal.
Using henna based powder hair dye will make hair dull and color will lose soon.
Frequent re-coloring will make hair look more duller.
So, here is a natural method to make long lasting hair dye using peel of layer over garlic.

PROCEDURE to make natural hair dye :

1. Take garlic peel(outer skin like layer) in large quantity because on making ash it will come to small quantity.
2. Roast the garlic peel on a pan till it becomes black ash.
3. Filter the ash to get fine powder with a cotton cloth.
4. Add olive oil to this ash to make it just like hair die.
5. Preserve it for 7 days(do not store in refrigerator) in glass bottle in darkness.
6. After 7 days apply it to hair in the same way as hair die. Preferably apply it at evening times and have head bath next morning.
7. For still better results don’t do head bath the next day instead keep it like that for 2 to 3 days and then have a bath.

This hair color will give natural black look to hair and will last for long period and also keeps hair healthy because of oilve oil mixture.
Also add biotin, zinc, iron, iodine and protein supplements to your diet to keep hair healthy and in natural color.