Sometimes I wonder if posts like these are plants by DAs or AGs.

Trees are usually ok planted year round in some cold locations (ask your local nursery).

When we visited the property, we noticed the new tenant had a lot of green grass and taken care of plants in his yard.

All ferrets should be confined when not supervised as they are strictly carnivores and can not eat plant based foods or anything of the sort that is not meat based. 

If a tenant asks about planting flowers, I tell them they are responsible for weeding.

I used to own my own company (Orchid and Hibiscus Nurseries) back home (South Africa) but found the market here in the USA not as fruitful and more streamlined to the pot plant industry as opposed to the connoisseur collector, definitely not enough to warrant further consideration.

You need to look at rental rates in your area, and if you have to weasel clause in your lease like the tenants must mow the lawn, water the plants/flowers, trim the plants, that could scare away tenants.

Lattice with plant?   

We're going to be taking two trees down from our new property (and planting more, in a place where they won't block the view) so I'll stay in touch with you!

I planted the REI seed with him already and he is going to be getting involved at a much earlier age than you and I (lol).