How can you encourage tenants to maintain the yard?

[Albert Tsang]

I have SFH investment properties in A to B areas and all have front and back yards. Based on my past experience with tenants, most will maintain the interior fairly well, but they will ALWAYS neglect yard maintenance even though it is written on the lease (e.g. mowing, trimming, watering...). I was hoping if some fellow landlords have strategies to encourage their tenants to maintain the yards.