A good boundary can add to the order of your garden space, offer an impressive visual statement and help protect your valuable plants. The border can make the difference between an average garden and one that functions more efficiently and needs less maintenance. A garden boundary can be formal or informal, decorative or practical. For the best results, choose a combination of border design ideas and combine them to fit your space and personal needs.
A border of companion plants---including herbs or flowers---can deter insects or help feed the soil for your fruits and vegetables. Marigolds are particularly useful in the garden. Cornell Cooperative Extension says marigolds can deter cabbage maggot, cucumber beetle and corn earworm. Nasturtium produces edible flowers and discourages flea beetles and whitefly pests. The woody perennial sage does well with many plants and chases away the carrot fly and cabbage loopers, while a planting of chamomile will provide an informal, low-growing border and won't shade out its neighbors. Native flowers and scented blooms attract bees and may help bring more pollinators to your space.
Very low-growing decorative shrubs are a good option for an established garden site you plan to use year after year. Small shrubs separate the space without blocking your view or preventing the sun from reaching your plants. There are many varieties that fall within the category of dwarf or very small shrubs, including Kalm's St. Johnswort (Hypericum kalmianum), Japanese white spirea (Spiraea albiflora) or the evergreen Canby Paxistima (Paxistima canbyi), which provides interesting foliage all year long.
A garden path can form a formal or informal border around your garden and allow visitors to better view your handiwork. A path following the full circumference of the garden---in addition to crossing through the center---is convenient for maintenance. Easy access to plants allows you to keep an eye on them both for enjoyment and to watch for signs of damage. Homeowners can choose from material varying from simple mulch to paving stones to create a functional walkway.
Fencing makes both a practical and decorative garden border. In most areas, protection is needed to spare your vegetables and flowers from feeding wildlife and from damage by neighborhood pets or children. Split rail or picket fences give your garden space an added layer of personality and can follow a theme. Chain link is a good option where pets are problematic. Chicken wire can deter rabbits and some burrowing animals. Bury a portion of the fence below ground level for added protection.