Everyone, wherever they garden, loves boxwood. As neat, rounded shapes, hedges, or growing untrimmed, this traditional garden shrub has a unique and distinctive look, with its small green leaves and dense growth. For gardeners in colder zones it can, sadly, be a frustrating plant to grow. Like most other broadleaf evergreens, it can suffer in winter cold, meaning scorched leaves, dead branches, and even a dead plant. In zones 4 and 5 it can be ‘touch and go’ every winter with boxwoods, but not if you grow the Glencoe Boxwood. This variety, developed in Chicago, has proven itself to be incredibly cold resistant. In the winter of 1993-94, when it was being tested, temperatures fell to minus 37o Fahrenheit, equivalent to zone 3, without any damage. It has a good dense, rounded form and rich green leaves, looking just like a classic English boxwood shrub – what more could we ask for?

Growing the Glencoe Boxwood

Size and Appearance

The Glencoe Boxwood is a dense, rounded evergreen, with many closely-packed branches, covered in small green leaves. It grows between 4 and 6 inches a year, and if left unclipped it will develop into a broad, oval plant, standing 3 or 4 feet tall, and as much as 5 feet wide. Trimmed it can be kept as small as 12 inches tall indefinitely. The leaves, packed closely along the stems, are less than an inch long, and they are rounded, with a slightly leathery texture, and a smooth, glossy surface. They are a rich, deep but bright green, and they hold that color well all year round, without bronzing in winter or yellowing in summer.

Using the Glencoe Boxwood in Your Garden

With its dense structure, the Glencoe Boxwood is a natural for clipping into hedges and rounded shapes. Like all boxwood it clipped well, re-sprouting quickly and very soon looking lush and fresh again. Use it to create hedges below 2 feet tall, spacing the plants 12 inches apart for a taller hedge, and 8 inches apart for a very low one under 12 inches tall. Use these hedges to edge your beds, giving your garden a classic formal look. Grow the Glencoe Boxwood as rounded balls to accent your beds or spaced out along a pathway. It will make lovely accents paired beside an entrance, or at the corners of a square or rectangular area. In zone 6 or warmer it can be grown in pots left outdoors all winter, around the garden or on terraces. In less formal gardens it can be grown unclipped. It will still be dense, but it will mature to a slightly irregular mound of great charm – try it.

Hardiness

The Glencoe Boxwood was developed in Chicago, and it is completely and reliably hardy in zone 5, and all the way into zone 8. As mentioned earlier, it has withstood temperatures of minus 37o, so you can be confident that it will be completely hardy in zone 4, where the minimums are only minus 30o. It is certainly also worth growing in zone 3, where protection from winds and spraying with antidesiccant is recommended.

Sun Exposure and Soil Conditions

The Glencoe Boxwood is versatile when it comes to light conditions. It grows most reliably in light partial shade, but it also has been tested and shown to perform well in garden areas all the way from full sun to light continuous shade. That might be in the shadow of tall trees, or of a building, or in light dappled shade beneath deciduous trees. It grows easily in almost all garden soils, preferring richer, moist well-drained soils, and not doing well in areas that are always wet and poorly-drained. Enrich the planting area with organic material and use it regularly as mulch.

Maintenance and Pruning

If you plan on clipping your Glencoe Boxwood regularly, we recommend you use evergreen fertilizer from spring into the fall. In colder zones stop fertilizing by late summer, to avoid developing soft new growth that is more easily damaged in winter. You can clip almost anytime, especially in warmer zones, but the best pattern is to clip in late spring, after the new leaves have darkened and matured, and then again each time new growth matures, ending in late summer to allow the last flush of growth to mature and toughen up for the winter. That way it will look most attractive through the cold months. For hedges and smaller balls it is best to clip lightly from the beginning, to develop a dense structure from top to bottom.

History and Origin of the Glencoe Boxwood

Boxwood has a long history in America, arriving with the first settlers, but it didn’t turn out to be very hardy in colder areas. As a result there is also a long tradition of developing tough, hardy forms suitable for northern conditions. The variety called ‘Glencoe’ was found among the extensive boxwood collections of the Chicago Botanic Garden, in Glencoe, Illinois, in the early 1990s, when they were testing for cold-resistant varieties. Its exact origin is not known, but experts tell us it looks very close to the hybrid variety ‘Green Velvet’, but more cold resistant. That variety is a hybrid between the English boxwood, Buxus sempervirens ‘Suffruticosa’ and the Korean boxwood, Buxus sinensis var. insularis, so it is possible Glencoe is a similar hybrid plant. The botanic garden, along with the Morton Arboretum in Lisle, Illinois and the Ornamental Growers Association of Northern Illinois have created a not-for-profit corporation called Chicagoland Grows, Inc. to promote plants developed for colder areas. They have trademarked this plant as Chicagoland Green®, a name for ‘Glencoe’ that you may see used.

Buying the Glencoe Boxwood at The Tree Center

The Glencoe Boxwood is a real break-through for gardeners in zones 5, 4 and even 3, so we know how fast these plants are going to be leaving our farm. Wherever you garden it is a top-pick rounded boxwood, of proven reliability. Everyone loves boxwood, so order what you need right away – they aren’t going to last long.