We recommend against 90° seams for a few reasons, but most importantly is the difference in tuft spacing when you turn the product 90°. Not only will the spacing change, the shape of the yarn will also be different when viewed from another angle.
Keep your grass facing the same direction on your seams to get the best result with minimal visibility.
As artificial grass products become more dense, the stitch rate goes up. That being said, when you turn a product 90°, you are attempting to line up a 3/8" tuft gauge with a much smaller spacing on your stitch rate. (our shaped yarn products vary between .22" and .29")