Home security can be as complicated as a big, expensive security system or as simple as some defensive plantings to discourage burglars. By landscaping with thorny, thick, or intimidating shrubs, you can actually decrease the chance of a home break-in. When burglars are seeking entry, they scan all the possible means of entrance. If these are ringed by sharp foliage and thorns, the thief will likely look elsewhere. Below are our top picks for defensive plantings, valued not only for their bite, but for their hardiness and full-season interest.
Prickly Pear (Opuntia)
The common prickly pear cactus is a pretty perennial and makes a lovely defensive bed. The low-growing shrub is only one to three feet high, but can exceed six feet in width.
In the full sun, the prickly foliage can quickly grow to fill a bed. There are about 30 varieties of prickly pear cactus, and some are the most cold-tolerant of any cactus. Some varieties even flourish in USDA zone two. In the mid-summer, the spiny foliage is adorned with large cup-shaped flowers in yellow, pink, or red. In the late summer these blooms turn to plump prickly fruit that can be harvested and eaten when the skin is a deep purple. But, be sure to carefully de-skin the fruit to avoid its sticky barbs. These spikes are what make the cactus such an excellent deterrent. Though not large in size, the spines embed themselves into the skin immediately upon contact. They are hard to see and even harder to get out. There is no way a burglar would attempt to climb into a window with these planted below.
The agave is a succulent plant, popular in the landscape due to its dramatic appeal and hardiness. Again, there are many varieties of agave, ranging from miniatures all the way up to the popular century plant, which can reach 15 feet in width.
Some are well suited to cooler environments, though all need dry, sunny conditions. All agave bloom in maturation, usually with an eye-catching flower stalk. Some agave have unusual fuzzy or variegated foliage as well.
The defensive appeal of the agave comes from its sword-like leaves, usually with a thick spine at the tip and abrasive serration along the sides of the leaf. Besides looking interesting and unique, agave look formidable. Most popular cultivars include "Felipe Otero", "tequiliana", and Agave angustifolia.
Barrel Cactus (Echinocactus grusonii)
The barrel cactus is what one typically thinks of when they think about "cactus." Barrel cactus are wide and stout, in the shape of, well, a barrel. The cylindrical plants can grow to be four feet tall and 2 1/2-feet wide, but grow slowly.
In the spring, clusters of yellow or pink flowers emerge from the top of the barrel, adding a nice splash of color. Year-round, the cactus is covered in golden spikes so thick you can hardly see the foliage below. Clustered together, these low-maintenance plants make for an intimidating border. However, barrel cactus are not cold-tolerant, flourishing only in USDA zones nine through 11. Plant them in full sun and water sparingly.
Although not technically a cactus, the yucca is a desertscape plant related to the agave. It shares the same growth habit, although the blade-like leaves of the yucca are more fibrous.
Yucca grows best in USDA zones four through 11 (depending on the variety) in full sun conditions. These plants are so drought-tolerant that they need not ever be watered—rain water is quite sufficient. In the late spring they shoot up impressive spires of creamy white flowers. Some varieties have red, pink, or variegated foliage. The pointy leaves of the yucca are like pokers and the sides are extremely sharp. Any of the varieties make a beautiful statement to neighbors and an intimidating one to burglars. Most interesting cultivars include Yucca aloifolia "Vittorio Emanuele II," Yucca glauca, and Yucca gloriosa "nobillis."
Pyracantha (Pyracantha coccinea)
Also known as firethorn, pyracantha is as beautiful as it is sharp. In maturity, this shrub can reach 12 feet tall and 12 feet wide, but it responds well to a heavy yearly pruning and can be maintained at any size.
In the mid-spring, pyracantha puts out bunches of delicate white flowers. These turn to heavy red or orange clusters of berries in the fall. In the winter, this evergreen keeps its small emerald leaves. However, what the pretty foliage, flowers, and berries conceal very well are the long thick thorns that decorate every stem. They are incredibly sharp and wonderfully plentiful. As a hedge, or just a simple planting under a window, pyracantha will discourage a burglar with just one touch. Pyracantha are very drought-tolerant and hardy in USDA zones six through 11. Some favorite cultivars include "Orange Glow" and "Flava."
Barberry (Berberis vulgaris)
The barberry bush has always been a mainstay in the landscape due to its attractive purple foliage, low growth habit, and adaptability. In fact, it is commonly planted in urban environments because it can adjust easily to poor soil and low water.
This hardy deciduous shrub can display multicolored foliage, with new growth appearing a dark purple or red and slowly fading to a bright green. Most varieties of barberry sport short, thick thorns that cover the plant almost entirely. However, many thornless cultivars are being developed so be sure to make your choice carefully if shopping for a defensive plant. The Wintergreen barberry (Berberis julianae) is known for its bronze winter foliage, yellow spring flowers, and extremely thorny branches, which makes for a fierce hedge.
Aralia (Aralia spinosa)
Commonly called the devil's walkingstick, Aralia spinosa is prized for its beautifully lacy leaves but also for its intense thorns that cover almost every part of the plan, including the petioles and leaf midribs.
This small tree can grow to 25 feet tall, but can be pruned to a more manageable size if needed. In the late summer, devil's walkingstick produces small creamy white flowers that turn to a small purple-black fruit in the fall. Also, the feathery tropical leaves change in the autumn from a robust green to an unusual bronze red and yellow. This cold-tolerant tree grows best in USDA zones four through nine in sun or partial shade. Just one glance at Aralia spinosa's formidable spines will send even the most determined burglar away empty-handed.
If you want some protection along the face of your house or a fence, consider a climbing rose. These thorny vines are also beautifully ornamental and some are fragrant as well.
By attaching a light wire trellis or plain chicken wire onto the desired surface, you can train a climbing rose upward by loosely tying the plant to the frame with dental floss. After a few months, the rose will figure out which way is up and climb all on its own. Then, all you need do is give it a yearly haircut to keep it looking neat on its frame. If you have a gate or fence that worries you, think about training the cultivar "voodoo" to cover any spots that could be easily scaled. Master gardener Fred Hoffman warns that this cultivar, while beautiful, is "more menacing than barbed wire."
Some other great deterrent plants include those that may not be spiky but are bushy and thick enough that a robber would not want to climb through them to reach your home.
Giant Rhubarb (Gunnera manicata)
The massive leaves and dense growth of the giant rhubarb plant are what earn this underused perennial its nickname: dinosaur food.
A rapid grower, giant rhubarb can grow to be eight feet tall and 12 feet wide and flourishes in full sun or partial shade. Although it will only grow in USDA zones six through eight, if planted in a protected spot and mulched heavily in the winter, the rhubarb may be able to withstand mild zone nine winters as well. While most of the other plants on this list like it hot and dry, giant rhubarb wants it wet. This makes it an excellent addition to a rain garden or to fill in a soggy spot in your landscape. The massive leaves are stunningly unique, but also abrasive and irritating when touched. This, along with its incredibly thick growth habit, make it a wonderful deterrent for anyone who has to climb through it to gain access.
Colorado Blue Spruce (Picea pungens "Glauca Globosa")
The Colorado blue spruce has the beautiful blue coloration of the common blue spruce, but will only grow to three to five feet tall instead of 25 to 30.
Thriving in USDA zones two through seven, the Colorado spruce is dense and particularly spiny. Known for their low maintenance requirements, it's both deer and drought-tolerant. Even though they’ll never get too tall, their spread can reach six feet in width, making them an excellent addition to a defensive garden—not quite tall enough for someone to hide behind, but certainly dense and sharp enough to bar someone from climbing through.
Common Holly (Ilex agulfolium)
The common holly is both dense and spiky, making it an excellent two-in-one deterrent. And the beautiful fall berries (on female plants only) and glossy leaves that stay throughout the winter are the icing on the cake. Moreover, they can tolerate both cold weather and drought conditions.
They do get big—anywhere from 15 to 50 feet tall and 15 feet wide. However, they are slow growing and are easy to keep to a certain size since they respond well to yearly pruning. The spikes on the leaves of the common holly are sharper and more pronounced than that of their cousin, the American holly. The common holly makes for an excellent hedge, one that any robber would think twice before trying to penetrate. It grows best in USDA zones five through nine.
Defensive Bed Tips
Although this may seem counterintuitive, it is best to keep the plantings in the front of your house below five feet in height. Even though you may feel that you want to screen your front entrance from prying eyes, tall, thick plantings actually offer people a place to hide and watch you, unseen. If you want to utilize a taller defensive shrub, like the giant rhubarb, place it to the side of the house where it is not blocking any windows. Otherwise, make sure you keep your plantings shorter than five feet, barring a nice tall hedge that rings your property. A dense, eight-foot holly hedge would be an excellent security system further from the home.
When planting your new security system, remember to wear long pants and a long sleeved shirt as well as thick gloves. Dealing with a plant as spiky as the agave or yucca will require some thick glasses as well. You’d be surprised how easily one of those spines can take your eye out! If planting one of the barrel cactus or prickly pears you may want to wrap portions of the plant in newspaper while planting and only touch the covered parts. With the prickly pear especially, make sure to wash your clothes immediately after touching it as the thin spines will probably embed themselves in your gloves and clothes as well. If you have children, make sure to warn them to be extra careful around your defensive plantings!
Most police officers will tell you: burglars are lazy. They are always looking for an easy target. Planting some of the deterrents mentioned above takes you right off that list. Burglars certainly don’t want to deal with traversing a bed of cactus and rose bushes. Thankfully, these little security systems are also hardy, unique, and beautiful.