Natural fabrics I mean 100% cotton garments or where the cotton content is high.
So here is my best advice; turn the garment inside out, so the print is inside the garment this will protect the print from the other clothes in the wash. Wash no higher than 40 degrees centigrade. Thirty degrees Celsius will give the best results and is eco-friendly too using less energy to heat the water.
Use mildest detergents and conditioners, do not use any whiters. These are usually some form of bleach which will fade the dyed fabric and damage the print.
Do not tumble dry. The tumble dryer reaches very high temperatures to dry the clothes and will shrink the clothes or remove the print from the garment. Also, the rolling motion of the drum will act as an abrasive on the print. Let the garment dry naturally either outside on a washing line (do people have these anymore?) or on a cloth horse. Try to keep the clothing as flat as possible; it will keep its shape better this way.