The Magazine — Gardening 101
How To Force Flowering Branches For Winter Blooms 0Deep in the winter any bloom is a welcome bloom in the house. In this weeks magazine we look at how to easily force branches from your garden at no cost and maximum enjoyment. Read more in our magazine.
Why Rhododendrons Curl and Droop in Winter 0
Now that the cold temperatures have begun to set in, ineveitably we get customers who are concerned about the drooping and curling of the foliage of Rhododendrons which they purchased in the past year.
I thought I would take a moment and explain that this is nothing to be concerned about, but a normal practice of many broadleaf evergreens. Thermotropism is a technique plants use to protect themselves from cold winter winds which may cause drying out of the leaves. Much like a human may wrap their arms around themselves when chilled or when animals huddle together, this technique helps protect the inner most part of the leaf where most of the moisture loss occurs. The colder it is the more they droop and roll. At the onset of warmer temperatures they will begin to unfurl and regain their shape.
An example of curled and drooping Rhododendron foliage during cold temperatures.
Moisture loss is the number one cause of winter injury in plants. It can occur in one of two ways. The first, as mentioned above, happens when a plant is subjected to cold drying winter winds. Ideally plants should not be planted in an exposed Northern position where they would take the full brunt of harsh winter winds. If they are, shrubs can be protected by wrapping them in burlap for the winter as an extra protection layer. The second, which is less well known, happens frequently when broadleaf evergreens are planted in a sunny Southern exposure. In this situation, on sunny winter days the foliage may get exposed to constant sunshine and warm to such a degree that the moisture contained in the leaf transpires. However, the trouble comes when the plant cannot bring moisture up from the roots due to frozen ground. The result is a plant consisting of dead, dried out leaves. For both of these situations an anti-transpirant, such as the well known brand "Wilt-Pruf" is recommended. This is a simple water based polymer spray which is applied in the fall before the onset of cold which helps the plants retain moisture in the leaves by covering it with a thin translucent film which does not let the moisture escape. It wears off over the course of several months. I always suggest that all evergreens have an anti-transpirant applied their first winter. Since most plants will not have their roots established fully into the surrounding soil, this spray is a huge help in establishing the plant through this crucial time. If your evergreens are planted in either of the above situations, it should be used every year as protection.
An example of Rhododendron foliage during moderate winter weather.However, be aware if your broadleaf evergreens droop, curl, or turn yellow in the warmer months of the growing season. In most cases this is indicative of poor drainage and exposure to excessive amounts of water around the roots. Plants in this case should be moved or provided a significantly well drained soil.
An example of healthy Rhododendron foliage during the warmer months.
Evergreens are the foundation of our garden plantings and can be the highlight of the garden in winter. By taking a few simple steps in their initial placement and ongoing care, they will provide you with years of enjoyment not only in the colder months, but in every season of the year.
Related Blog Post:
The Difference Between Evergreens and Conifers 0
This time of year my plant friends begin to throw around words like "Evergreen" and "Conifer" somewhat indiscriminately. Some know what their talking about, others... well not so much. Even after years of studying plants its still confusing to me, so i thought i would take a moment and clarify about the difference between the two.
An example of a needled evergreen pineThat part is fairly straightforward. A needled evergreen can also have "awl-like" foliage such as a Juniper, or "scale-like" foliage such as Arborvitae.
An example of "Awl-Like" evergreen foliage on a juniper
An example of "Scale-Like" evergreen foliage on an arborvitaeThe second category of evergreen are the Broadleaf Evergreens. This category has flat foliage which can range from the tiny foliage of Boxwood to some of the larger forms of Rhododendron and Magnolia.
An example of the smaller broadleaf evergreen foliage of boxwood
An example of large broadleaf evergreen foliage of rhododendronIts all pretty straightforward. That is until we come to conifers...
Conifers are defined as trees which are strictly "cone-bearing". Now at first glance we think that it is pretty clear- all evergreens produce cones. Right? Not quite. There are many evergreens which do not produce cones, but produce berries - for example - Junipers. Junipers and others similiar to them, therefore are not conifers, just evergreens. To make matter more confusing plants such as the Larch loose all their needled foliage and bear cones. They are therefore considered conifers.
An example of larch- A conifer which drops all its needles in winter
The 1/3rd Rule of Pruning Clipped Shrubs 0
We all have the annoying yew or boxwood which over the years has grown way to large for the space it occupies or has become misshaped with age as the result of pruning exclusively with hedge shears. These plants always end up with a leafless center and all of the growth on the exterior surface of the plant. Inevitably the only option ends up being removing the shrub and replacing it with a new smaller one or hacking it back to bare sticks and living with it for several seasons. The 1/3 Rule of Pruning is a technique professionals and nurserymen use to maintain the shape - and more importantly - the health of the plant. By using this technique you can extend the life of your clipped shrubs and end up with a plant which is gorgeous to look at all times of the year.
Over time clipped shrubs can easily develop dead zones in the center of the plants from constant clipping with hedge shears. It also results in plant growth thickest on the outside of the plant, closest to the sun and air, where they develop "Witches Broom".
The 1/3rd technique stops this from happening. The idea is to remove roughly one third of the interior branching every year to increase light and air to the interior of the plant which will increase new fuller growth from the inside of the plant. Over the course of several years, it results in a plant which is fully formed and flushed with foliage throughout its shape. It can then be shaped and maintained to the desired form easily.
Explore and identify 1/3 of the larger witches broom from within the plant. Make sure to look on all sides as well as the tops.
Step 2Clip the branch out of the shrub. Don't necessarily take just the ends off, but go deeper into the plant and remove as much of the woody stem as possible and still keep the rough shape of the plant. This may create a bit of an open pocket initially within the plant, but don't worry, this will fill in over time and help create a full shrub throughout.
Example of the Witches Broom removed.