How to Plant and Grow Red-Twig Dogwood
Where will they grow?
Red-twig dogwood, known botanically as Cornus sericea (and formerly known as Cornus stolonifera, a name still in popular use) is extremely cold tolerant, thriving even in frigid USDA zone 2. It is not terribly heat tolerant, however, and is not recommended for areas warmer than about USDA zone 7, especially hot and humid climates. It occurs naturally throughout a good portion of North America, and is often found growing along riverbanks, streams, drainage ditches, and ponds or lakes.
Red-twig dogwoods get their name from the bright red hue their stems develop in winter. This color fades during spring and summer, redevelops as autumn temperatures get cooler and the days get shorter, and are at their showiest during winter, when the plant is leafless.
These shrubs will grow in full sun or full shade, though the color and habit is best with at least some sun each day. If you are growing them to attract spring azure butterflies to lay eggs, sun in spring and early summer is especially important.
Wet or dry, clay or sand, acidic or alkaline, red-twig dogwood can tolerate it all. It will even grow in mud or standing water, so go ahead and plant it even in a difficult spot. If humidity is very high, leaf spot can develop. While it may be unsightly, it won't harm the plant.
Thanks to its durability, red-twig dogwood firmly falls into the "easy care" category. But there is one important thing you need to do to keep them looking their best, and that's regular (or at least, semi-regular) pruning. The bright red color on red-twig dogwoods is only seen on stems that are one and two years old. When they get much older than that, the color is obscured by brown, corky, bark-like cells. There are two different approaches you can take to keeping your plant looking its best.
One option is to cut the whole plant back to small stumps in early spring each year, or every other year. This may seem extreme, but it will regrow quickly in the following weeks. This simple approach keeps the plant smaller, but it has two disadvantages: one, it removes the flower buds, eliminating the bloom and any potential for berries to form, and two, it leaves you with no plant for a few weeks while it grows out of the haircut.
The second option is to remove one-third of the oldest stems each year in spring. This practice would be started after the plant had been in the ground two or three years, and each year, you'd remove the oldest third. This preserve the flowers and a larger plant, but it does require a bit more careful selection of which stems should be cut.
It's also perfectly okay if you don't want to do either of these things. The plant then would only have bright color at the tips of its stems each year. If, at any point, you decided you want to try one of the measures above, you could easily start implementing them the next spring.
Red-twig dogwoods have very low fertilizer needs. If you were to do an extreme pruning on an established plant, you may wish to apply a granular rose of garden fertilizer at that time, which can help speed the recovery, however, this is not strictly necessary.