After that custom landscape is created in your yard, the last thing you'll want to deal with is an intruder ruining the layout and getting into your home. Landscaping is an unsung hero in home security, and you can use your landscaping to both protect the house and really annoy (if not scare) someone sneaking around. This is about more than just trimming shrubs away from the door so you can see who's around; this is about creating a landscape that is stunning and secure.
Each time you decide on a type of plant, look for a high-security cultivar. Bushes and flowers with thorns and spiky leaves are excellent barrier plants that make accessing anything behind them really unappetizing. HGTV suggests the 'Voodoo' rose cultivar as well as Oregon grape holly; both have alarming amounts of thorns and spiky leaves. Cacti are classic barrier plants and don't ramble, so if you need to protect a small area or stop vandals from reaching your house through a break in shrubbery, a cactus would be a great choice.
Space as Defense
Just as spiky plants close to the house can stop trouble, so can moving back plants that might help people gain access. A tree with long branches is an example. Plant that too close to the house, and people can use the branches to access windows and upstairs balconies. (Plus you'd have an increased risk of pests accessing the attic or crawlspace.) Move plants like trees back from the house while moving the spikier plants closer to the structure.
Another placement issue has to do with rare plants. Plant theft is a real thing, and people often try to steal whole plants or take cuttings. Place rare plants in your backyard, out of view of the street or access points like gates. Make the front yard fairly tame in terms of interesting plants that might be hard to find. If you have planters, lock them down so that grabbing one would be difficult to do. Also remember to monitor your yard frequently so you can see if anything is missing or has been damaged.
Carefully designing your yard might not be the main way that can protect your home, but it's one you shouldn't ignore. Every bit counts, and if you are arranging for a custom landscaping job, you have a chance to make your yard nice and secure.