Grafted Plants: Rootstock Rebellion

I have not done much plant grafting. During my undergraduate studies I grafted pink geranium shoots onto a white geranium, resulting in a rather ugly specimen. Most of my experience with grafted plants has come in the role of caring for plants that have been grafted in nursery and landscape settings. When plants are grafted there are two parts: a rootstock and a scion. The rootstock, which may also be called an understory, that is the part of the plant that has the original root system. Many times the rootstock is selected for disease resistance or strong growth. The scion is the shoot that is grafted onto the rootstock; it is usually selected for ornamental value. Since grafting is labor intensive and requires special skills it is only done in the commercial market when it makes economic sense. There are many reasons grafting is conducted, but the dominant reason is to asexually propagate a plant with desirable characteristics. This is particularly true in the case of hybrids and genetic oddities, when sexual reproduction is not possible or would result in loss of desired characteristics.

After a graft has healed and the vascular tissue has been joined, the primary task in plant management is to keep an eye on the rootstock. Many exceptional ornamental plants are produced by grafting a scion from a hybrid onto a rootstock from one of the parent species. A rootstock might produce shoots that compete with the scion, and if left unsupervised, might overtake the scion. Here is an example from a looming problem on a hybrid witch hazel I saw today:

An uprising begins.

The little shoot rising from the rootstock must be terminated. It will have inferior ornamental attributes compared to the scion and will likely be more vigorous. Right now the uprising can be quelled in a few seconds, one quick cut with a pruners. I posted a picture of a leaf from this particular hybrid witch hazel earlier this fall. The scion has dramatic colors, while the rootstock shoot will be a weak yellow.

A vibrant hybrid witchazel (Hamamelis x ‘Diane’).

As a horticulturist I notice grafted plants in landscapes that have reverted to, or are in the process of reverting to, the rootstock. What appears to the untrained eye as a peaceful looking plant might in fact be two strong-willed, competitive individuals functioning as one organism.

Coast to Coast

October has been crazy. Crazy in a mostly good kind of way. I’ve been very busy.

I spent part of last week on the central coast of California for a job interview. After a few days by the Pacific Ocean I flew east, arriving in Avalon, NJ to spend a long weekend at a beach house with family. It has been a weekend full of great conversations, food, and fun. Here are a few pictures I took recently by the sand dunes and buffer forest beside the ocean.

Grasses on the sand dunes.

Sassafras celebrating the fall.

Euonymus americanus capsules, mixing pink and orange.

Beautiful poison ivy.

More poison ivy, looking exceptional.

I’ve said it before, but it bears repeating. The Jersey Shore is wonderful in the fall.

Every Day is a Winding Road

I’m still in a season of waiting. I think active waiting is far more bearable than passive waiting, so I’m staying busy. Right now I’m working part time at Behmerwald Nursery, writing and editing manuscripts, preparing for interviews, and compiling job application documents. Yes, every day is a winding road.

I’ve been savoring this autumn. Today after work I photographed a few of the plants at the nursery in all their fall glory.

A Northern red oak (Quercus rubra).

A hirsute oakleaf hydrangea (Hydrangea quercifolia).

A vibrant hybrid witchazel (Hamamelis x ‘Diane’).

A dapper Dart’s Duke viburnum (Viburnum x rhytidophylloides ‘Interduke’).

A Quickfire panicle hydrangea (Hydrangea paniculata ‘Bulk’).

A very red shasta doublefile viburnum (Viburnum plicatum f. tomentosum ‘Shasta’).

And I took a low resolution self portrait with a Japanese stewartia. The stewartia will look amazing in a few weeks; it is one of my favorite fall plants.

Green stewartia leaves–soon to be red and orange.

 

Frogs and Plants

After work today I took a few pictures of frogs and plants. I’ve always liked frogs. A frog examined closely is a beautiful thing (preferably not with biology lab intensity, no blades are needed to appreciate a frog).

Aren’t they cool creatures? Look at the colors, textures, and shapes. Extraordinary.

Changing subjects, Hydrangea paniculata has come a long way in the past decade. Many of the new cultivars on the market are excellent. One of these cultivars has a registered name of Pinky Winky®. Its botanical name is Hydrangea paniculata ‘DVPpinky’. The flowers of Pinky Winky are arranged in a panicle, with sterile and fertile flowers. After opening up white, some of the flowers will darken to a pink color. It looks great in the fall.

An aged Pinky Winky inflorescence.

Blackberry lily (formerly called Belamcanda chinensis, now called Iris domestica) is a rather informal plant for the garden. It has small, bright orange flowers that are speckled with darker colors. I think it looks very cheery in the summer. By now all the flowers for this year are gone, leaving seed pods behind. Can you guess where the name blackberry lily comes from?

The seed pods of blackberry lily.

Here’s a picture of a plant with open seed pods. Makes it obvious, doesn’t it?

Blackberry lily seeds.

Fall is for Planting

Right now is a good time to plant trees, shrubs, and perennial plants in the mid-Atlantic region. Planting in the fall is wise for several reasons. The most compelling reason boils down to this: planting in the fall requires less work than planting in the spring or early summer.

When a plant is installed in a landscape it goes through a period of time when it is very vulnerable to water stress. I feel confident in saying that in landscape settings the majority of plants that die within one year of planting do so due to a lack of water. A very large percentage of the plant-planting population do not understand how to properly water a plant. In most cases rainfall is not enough [1].

Having plants installed in the spring or early summer is signing up for intensive plant care. The plants are counting on you to provide water until they develop a root system. And this is why planting in the fall is a good idea. In the fall the soil is still relatively warm from the summer, while air temperatures are falling. The high soil temperature encourages root growth, which reduces the amount of watering you will need to do. The cooler air temperatures reduces the transpiration rate, which reduces the amount of water the plant needs to survive. This translates to a reduction in plant care when compared to the spring or early summer. By the time the winter ends and things begin to warm up for the following summer, your plant will have a respectable root system in place.

If the thought of watering newly installed plants keeps you from adding to your landscape, or if you’ve killed plants installed in the spring or early summer, you should give fall planting a try. We’re entering the best time to plant right now. The next 4 to 6 weeks are prime for fall planting.

As a disclaimer I feel I should mention hardiness. If you stick to plants that are reliably hardy you’ll have no problems with fall planting. If you want to try pushing the boundaries with plants that belong farther south you are best off waiting for the spring [2].

My advice is this: add a few plants to your landscape soon. Find a good spot for Hydrangea paniculata ‘Quickfire’ or Weigela florida ’Wine and Roses.’ Or maybe try adding a new tree, like Acer griseum or Cornus kousa. There’s never been a better time to plant.

[1] This is a post in itself, but I’ll save that for another day.
[2] Growing marginally hardy plants is another topic that bears further discussion–it’s all about microclimates and selecting the right sites.