Used by women for hundreds of years in an effort to get vibrant bleached locks, lemon juice is one of the oldest and most effective natural lightening techniques. Pour lemon juice into a spray bottle and coat your strands completely. Let it dry for about 20 minutes before rinsing out again. Lemon juice can dry out your hair when used often, so mix it with a bit of oil to keep your hair soft. Afterwards, do a deep conditioning treatment on your hair. If you have brown hair, make a pot of extra-strong coffee. Let it cool completely, putting it in the fridge if necessary. Pour the cold coffee into a spray bottle, and spritz it all over your hair. Sit in the sun for about half an hour. This won’t lighten your overall color, but it will brighten your natural highlights. The naturally light coloring of chamomile and the natural chemicals of the blooms combine to bring out blonde undertones in hair. Steep 1-2 teabags per 100 milliliters (3.4  fl oz) boiling water. When the tea is completely cool, spray it on your hair, comb it through, and sit in the sun for about 30 minutes to bring out natural highlights. Similar to chamomile flowers, marigolds can give the golden highlights you’ve always dreamed of. Put 1 cup of water, 1 cup of apple cider vinegar, and some dried marigold flowers in a pot and bring it to a boil. Strain out the flowers and let the liquid cool completely. Put it into a spray bottle, spritz it on dry hair, massage it into the scalp, and let the hair air-dry. Boil some rhubarb root, let the liquid cool completely, and test it on an inconspicuous lock before applying it to your whole head. Rhubarb adds a yellow tint, so if your hair is already very light, it could end up darker.

TL;DR in Vietnamese:
Xịt lên tóc nước chanh. Pha một tách cà phê. Làm trà cúc La mã. Dùng cúc vạn thọ khô. Dùng cây đại hoàng.