I had an interesting email the other day, from someone wanting a gardener for their house, which they were about to rent out.
Stupidly doing myself out of a job, I advised them not to get a gardener, but to find a local contractor - they usually call themselves "landscape gardeners" - and pay them to go in three or four times a year to chop back and keep it neat.
Why did I advise this?
When you rent out your house, you are doing so because you are not able to live in it yourself for a while, but you don't quite want to sell it: whatever the actual reasons, this is what it boils down to.
Leaving a house empty is a bad idea for a dozen reasons, as it will deteriorate rapidly, so having someone pay you to keep it aired is the best way to go. Of course, they will dirty it, break things, and so on, but you have to accept it.
In the same way, tenants will totally fail to love your garden. If you are very lucky, they will cut the grass: but that's the best you can expect. As for the rest, they usually neglect it completely, let their children run around and trample things, and allow their dogs to foul all over it. It's therefore best to assume that they will do nothing, and to arrange for a firm to do it. It also, subtly, reminds them that you are keeping an eye on the place...
This future landlord was a bit upset at the suggestion to get contractors in: they said that a friend of theirs had used contractors in the past, and was really unhappy with the job that they did. "Soulless" was one word used, along with "butchered the shrubs".
I was able to confirm that yes, most so-called "landscape gardeners" are indeed butcherers of shrubs: but an important part of renting out your house is to take a step back, and disassociate your heart from the property, for a while. The same goes for the garden - even though it was a much-loved garden, you have to accept that it is going to be neglected for a while.
In the meantime, contractors will keep things down to a reasonable size, they will prevent any monsters such as brambles etc taking over, and - most importantly - they will take away the rubbish that they create. And they are a lot cheaper than paying a top horticultural rate to me!
And the good news is that it's all right: gardens are very resilient, and no matter how badly butchered the shrubs have been, within a couple of years of you returning, they will be back in shape.
"Really?" they said. "How come?"
Most contractors go round with power tools, they take the hedgetrimmers and/or chainsaw and make sweeping movements around the shrub, up, across, and down. This is known in horticulture as "bunning", ie making a bun-shape out of something. Or "lollipopping" if they leave a short trunk on it. The result is a sort of bastardised topiary: a thick clump of foliage on top of a bare stem, which is a far cry from the elegant shape and form of a properly maintained shrub and, depending on when they do it and how horticulturally ignorant they are, it might never achieve full flowering. But at least it's neat: it allows light to the ground below it, and keeps it down to a reasonable size.
When you return, you can go back to the proper regime of cutting out one-in-three of the main stems, right down to ground level, each year, and in three years you will never know that it had ever been butchered: but in the meantime you can thin out the thick head of short bushy growth to make it look more natural: and of course you will be able to work all round the shrubs, to weed and replant any herbaceous items that did not survive, to recut the lawn edges, and so on, as it won't be a tangled mass of nettles, bindweed, brambles and so on, which it might well be if you left it up to the tenants to maintain it.
So that's my advice: put your heart aside, accept that the garden won't be loved for a while, pay the contractors to chop it back every few months, put in a clause to the tenancy agreement about cutting the grass, and make sure you leave a cheap mower in the shed for them to use (or pay the contractors to cut the grass once a fortnight, if it's a big lawn) then when you return, you can always call in a Professional Gardener to help you restore it!