When you buy a house, usually there's a garden coming with it.
For a new built house the garden is most often bare ground. The landscaping has to be started from scratch.
In case of a house that's already been inhabited, the garden was designed by the previous owners. And that may not (or not exactly) be to your liking.
That's why it's sensible to take into account the cost of landscaping when buying a house in the Netherlands.
Five to ten percent
As a rule of thumb (that I used when I was a realtor), the cost of landscaping will be in the range of five to ten percent of the purchase price of the house. The final cost depends, among other things, on how much you're able to do yourself and how luxurious the garden has te become.
Another approach could be the costs per square meter (Dutch metrics). These are starting at eighty euros (per m²) going up to fourhundred euros or more (per m²). This again depends on how much work there's to be done and how abundant the garden has to be. When the only thing you need is gras, the cost will much less...
You can find realisic example calculations (for landscaping of complete gardens) at casadata.
Who's doing the work?
When you don't have any gardening skills and you don't have skillful parents to help you, (or you just don't have the time or willingness to maintain the garden), you could hire a gardener to do the job for you.
The gardener can probably do both the design and the construction. If he can't, he'll know a landscaper to consult for the design.
If you want to know how much your prefered garden will cost you, you can ask a gardener. He'll be able to make you an accurate offer.
Most often it's easiest to build a garden from scratch.
The adjustment of an existing garden may be a little more difficult. When you have to redo the whole garden, this may mean significant additional costs.
When you buy a new build house, you'll often be able to finance the landscaping.
You can include the costs in the mortgage. This way you don't have to use any of your own money (if you have any) to finance the landscaping.
If you buy an existing property, you buy the house including the garden. You'll usually get a mortgage for the total purchase price.
When you subsequently want to change the garden, you may be inclined to pay this from your own money.
That is not always necessary. When the new garden raises the value of the house, it may be possible to increase the mortgage as well. You might pay your new garden this way too.