One of the biggest challenges I face is keeping the beautiful gardens I design, beautiful. Once the plans have been installed, I'm no longer needed, and all I can do is watch from the curb as my so-carefully-considered perennials turn into shaggy messes... shrubs sprawl… and roses blow their brains out in the heat of summer. Even though I tend to emphasize waterwise, low-maintenance gardens, I just never know how much TLC they'll actually get.
That's why one of the first questions I ask a client is, "how much do you intend to spend on a gardening service each month?" If their answer is "nothing, I'll take care of it all," I know we're in for a rough ride. On the other hand, if they say, "oh, a few hundred or more," then I know they're more realistic about their abilities and their garden's needs.
The best recommendation I can make is to hire not just a lawn-mowing service (and if I'm designing your garden, you won't have much of a lawn to mow), but a fine gardener: someone who knows (or will learn about) your plants in detail, who will prune them when they should be pruned… feed them what they love to be fed… and even evolve the design over time with annual color and replacement plants that enhance the design.
The best fine gardeners aren't cheap -- $75/hour is possible -- but they are so worth it when your garden blows away anyone else's in the neighborhood, every day of every season of the year. A good design with a great gardener? Priceless.