Cutting the lawn too short or too long is likely to cause damage and be prone to lawn disease, drought or heat damage. Creating stripes in your lawn is reliant on the grass not being too short or too long, around 30mm should be just right. Always follow the 1/3 rule, do not cut more than 1/3 of the total length of the grass blade and follow regular mowing schedule, normally once per week during the growing season.