It’s the third week in May, and the Wisteria floribunda ‘Blue Eyes’ which covers our pergola has begun to drip with fragrant blossoms. It’s certainly a sight, and elicits ooh’s and ahh’s from nursery visitors. Conversation immediately turns to pruning advice, and the question we hear over and over again, “Why hasn’t my Wisteria ever bloomed?”
We’ll cover extensive pruning Wisteria advice in a later blog posting, but let me address the flowering question. Wisteria often take several years to bloom after transplanting as it is concentrating energy on establishing a firm root system, but there are other points to consider. First, plants should receive a good 6 hours or more of sunlight. Also, do not fertilize with a high nitrogen fertilizer. Wisteria are in the legume family, and fix their own nitrogen from soil. Select a fertilizer with a high phosphorus # (the middle number) such as 5-10-10, 5-10-5, or Espoma’s FlowerTone which is a 3-4-5.
It is advisable to select named clones which have been propagated from productive flowering stock. Wisteria grown from seed are quite variable in their blossom production, and some have been known to never produce a bud. Another thing to consider is that Wisteria sets buds on old wood, and should be pruned in late spring after flowering (or when it should have flowered) to about 6″ from main branches. One other trick is root pruning in early spring. Using a sharp a spade, dig in about a 2′ radius from the base of the vine. This will sever the roots and may shock the plants into flowering.
Shadows at the Getty
Woody plants don’t need any help from our saws and secateurs. They would all produce much more growth if we just left them all alone. So why don’t we abandon them to their feral origins? Forsythia, Calycanthus and Winterberry, just to name a few, most definitely look their best when we let them go wild. That’s the point, isn’t it, to look their best.
Unfortunately, the majority of our cultivated garden woodies need a little help to get ready for the party, and some need to freshen up several times during it. So, we prune plants to control their shape, size, flower production, fruit production, density, cast shadows, let in light, obscure light etc. We do this solely for our own amusement, but the results can make an enormous impact in our landscape. Sometimes the effects are sublime.
Composition of Light and Dark
Unless you are a gardener familiar with good pruning practices, you may not recognize their effect in the garden. The woody plants will appear handsome, well shaped, symmetrical or amorphous yet balanced. The common observer will think these plants grew naturally into these forms. However, when woody plants are left unpruned, their messiness will be noticed, and you, as the garden steward, will get the blame. It’s like making and implementing a decision that avoids a disaster: no one sees the disaster prevention happening, so your good judgement and actions go unnoticed. That’s okay…you know what you did and people with a discerning eye will also know. Good pruning elevates your landscape to another level and it’s never too late to start.
This is the third in a series of blogs preceding our upcoming pruning workshop. Today we’ll examine growth habits and regenerative responses. Make the most of our upcoming workshop but reading through this series of blogs first. For questions, address Chris @ email@example.com.
Let’s review each of our five plant categories:
Semi-open Form Conifer
Deciduous Conifers– This group produces a central leader. A central leader is a single trunk headed straight up to the sky. Structurally, this is the best of all growth habits. It is pretty much impossible to prune them into any other form; they will always revert to a single leader. Their branching is symmetrical. This group regenerates well because of the dormant buds present throughout the trunk (old wood).
Evergreen Conifers– Of the tree forms, some naturally produce a central leader while others produce multiple leaders. Most can be trained to a central leader if you have the patience and start training them in their youth. Multiple leaders have the tendency to spread apart under snow and wind loads. This group does not regenerate well because dormant buds are not present on old wood. Small shrubs forms of evergreen conifers will be addressed in the workshop.
Broad Leaf Evergreens- Most are multi-stemmed and should be left that way. These produce many stems from the base as well as many primary, secondary and tertiary branches. This group regenerates well; they will sprout from old wood, when damaged or presented with more sunlight as dormant buds exist throughout.
Open Form of Deciduous Shrub/Tree
Deciduous Trees-Some naturally produce a central leader while others produce multiple leaders. Most can be trained to a central leader if you have the patience and start training them in their youth. Although snow and wind loads are not as detrimental to this group, they have greater stuctural integrity as single leader specimens. Most have strong regenerative response to pruning, damage and increased light exposure.
Deciduous Shrubs-Most are multi-stemmed and should be left that way. These have strong regenerative properties and can be cut back as far as you’d like (if you don?t mind foregoing a years blossoms).
In general, Alternate branching plants are easier to prune into “open forms” by a process called thinning out (think apple trees in an orchard or well-tended Tea Roses), but don’t respond as well to extensive tipping back (shearing), which produces that scrumptious chicken croquette shape. The exception to this occurs when the alternate branching pattern has short internodal spacing (the distance between one branch and the next is very short). Many evergreens such as boxwood, yews, and arborvitae produce closed forms without any help from shears because of their short internodal spacing. Opposite branching plants generally take more work to prune into open forms, but in many instances it is worth the effort. This branching habit tends to produce a “closed form” and shearing only intensifies this, often resulting in the “cartoon strong man form”, all upper body with skinny little legs.
This is the second in a series of blog posts leading up to our April 17, 2011 pruning workshop. These posts will address things you should be familiar with before you take pruners to plants. If you’ve signed up for the workshop, we encourage you to read through blog posts.
In the blog entry Pruning 101, you were asked to identify the plants you are intersted in pruning. With plant names now in hand, you next need to decide which of the following woody plant groups your tree/shrub falls under.
- Conifers deciduous e. g. Larix (Larch), Metasequoia (Dawn Redwood), Taxodium (Bald Pond Cypress)
- Conifers–evergreen e. g. Pinus (Pine), Picea (Spruce) Abies (Fir)
- Broad Leaf Evergreen e. g. Rhododendron, Ilex (Holly), Pieris (Andromeda)
- Deciduous Tree e. g. Acer (maple), Quercus (Oak), Stewartia, Fagus (Beech)
- Deciduous Shrub e. g. Rosa (Rose), Viburnum, Salix (Willow), Spirea, Vaccinium (Blueberry), Lavandula (Lavender)
These 5 groups are your launching off point: each embodies of group of plants that generally have specific growth/branching habits and regenerative responses/capabilities. We will leave the regenerative processes for the next blog.
Growth and branching habits are responsible for growth patterns in all plants and they fall under one of two groups, alternate or opposite. Alternate branching occurs when only one new shoot/leaf node develops along a plant limb at any given point while the next developing shoot/leaf node occurs at a different point on the opposite side of the limb-see example. Opposite branching occurs when two new shoots/ leaf nodes develop at the same point along a limb, but on opposite sides of the limb-see example. Although the examples here are clear, it is often less so because there can be a considerable amount of variation. Make an attempt to differentiate these patterns on your own plants, while noting their variability. We will examine what this variability means to the pruning process when regenerative responses are discussed in the next posting.
This will be the first in a series of blogs leading up to our April 17, 2011 pruning workshop. That stated, this article will help everyone on there way to pruning, even if they can?t join in the fun on April 17th. These blog posts will address things you should be familiar with before you take pruners to plants. Make the most of our upcoming workshop by reading through thisseries of blog posts. For questions, address Chris at firstname.lastname@example.org.
Styrax japonica in winter
Every plant has a name, both Latin and common. For a beginner, knowing one or the other is crucial. If you don’t know either, then it’s impossible for any professional to tell you how to prune it. Photographs will help to identify it. Let’s assume it is the off seasons, late fall through early spring, when all our deciduous plants are posing unclothed, their bare limbs shivering. You will snap 2 or 3 photos: one of the entire plant, and one of an individual 8 -12″ section of an outer limb, and perhaps one of the trunk or base of the plant. If you think that the bark or the terminal buds (the very end of the branches) is unique, than snap a photo of that too. Make notes about anything you recall it doing in the previous year, e. g. “It bloomed white on Mother’s Day” or “the fall color was butter yellow”. Send this information to Avant Gardens (or a good local nursery) via email and we’ll help you out (you might want to reference this blog to let us know you’re not sending spam; we get nervous opening up attachments from senders we don”t know). Don’t be shy. People in the plant trade love to share information!
If the growing season has begun and plants have leafed out, take three photographs: one of the whole plant, one of the plant in flower (if it does bloom), and one showing a small segment of branch with leaves attached. Does your plant has some other distinction, like mottled bark, unique cones, columnar habit, scent, etc? Snap that picture or make notate these observations. Make note of anything you remember about that plant that will help identify it. ( A note that your mother-in-law gave it to you probably won’t aid in identifying it, unless of course she remembers what it is– and it is not a problem to ask her. ) Remember that you can always ask us at Avant Gardens or check your local nursery.
Examples of helpful shots are:
Chamaecyparis obtusa ‘Fernleaf Gold’
Hydrangea paniculata ‘Limelight’ blooms on new growth
Even seasoned gardeners seem to be confused as to when to prune Hydrangea.
Begin by identifying which Hydrangea species you are growing, to determine whether it will bloom on new growth or on old wood (last year’s stalks). The species arborescens, paniculata and some newer forms of macrophylla bloom on new wood. All the Hydrangea macrophylla (Mophead and Lacecap types) and quercifolia (Oakleaf) bloom on old wood, as long as there isn’t winter damage. Next year?s blossoms are set on the upper portion of the woody stalks in late summer and fall. H. macrophylla selections should not be pruned until after the plants have leafed out. In late spring, prune out or tip back any dead wood for a clean appearance.
The hardiest and most foolproof of all the Hydrangea are the paniculata group (Pee Gee types) and the arborescens group (Smooth Hydrangea). Both of these species can be cut within inches of the ground each spring if you want to control the size of your plants. They stalks can always be thinned to improve plant shape, and there is no harm to next year’s display if you want to cut long stemmed bouquets in summer and fall.
There are a lot of new Hydrangea macrophylla selections on the market, including ‘Double Expressions’, ‘Red Sensation’, ‘Let’s Dance Starlight’, and ‘Endless Summer’ that bloom on old and new wood. The blossoms appearing on old growth will display in early summer, while the flowers that form on new growth will appear later in August and September, for a long continuous display. If you live in the colder parts of zone 6 or zone 5, you may get too much winterkill for blossoms on the old growth, but you will still be able to enjoy a late summer through fall display.