Hand tied extensions can work well on short hair, as long as there is enough length to attach the extensions. Typically, the natural hair should be at least 4-6 inches in length for the extensions to be installed properly.
It's important to consult with a professional stylist to determine the best extension length and placement based on the natural hair length and desired style. If the natural hair is significantly shorter than the desired extension length, it may be necessary to add more than one extension row or use a different extension method to achieve the desired look.
Also, it's important to consider the amount of hair and density of the natural hair when deciding on the number of rows and amount of extensions to add. If the natural hair is fine, it may require fewer extensions than someone with thicker hair to achieve the same look. It's always best to have a consultation with a professional stylist to determine the right approach for your hair type and desired outcome.