If you want to try how red hair would look on, you could try hair dying with beetroot. It is very temporary and does not get into the hair; this is its difference from henna. Beetroot juice will not create an opaque layer but it will only give your hair a shade of red. In order to maintain this shade beet juice needs to be reapplied every week, which will let you get rid of the dye fast. On the other hand if you like the colour it will need more work to keep colour.
It does not have a specific result and will depend on what colour you start out with. For example silver or pale blonde hair will become pink or purplish and darker tones will become plummy.
If you have a juicer then that is the way you can get the juice, if not water from cans in canned beets. Take 1/2 of that and mix it with a couple of spoons of sugar and 1/2 cup of carrot juice. Heating up the mixture will help activate it and will make it more pleasant to apply.
The mixture should be applied to damp and preferably warm hair. Dip the whole length of hair into the juice. Then put on some gloves and spoon the rest of the mixture onto your scalp. Make sure to get all the roots. Another way to do would be putting the juice into a spray bottle and spraying hair and scalp with it.
Put Vaseline onto ears and hair line so the beet juice won’t stain your skin.
Cover the hair and scalp with a plastic bag and sit somewhere where it will be warm. Sitting in the sun or using a heat pack would work. Heat helps the juice take better. The mixture should be left for at least half an hour, after rinse out with cold water. If you want to use shampoo you can but the dye will last longer if you use just water.
Keep using beetroot juice every week or every other week until you get the tone you want. After that you can do it once every two or three weeks.
For a more permanent colour henna would work better.