No room for bad attitudes…

Well- spring is in full effect. It’s the time of year when we watch excitedly as our ‘garden babies’ emerge and grow with each passing day and we curse under our breath (or aloud) when our weeds do the same.

The striking spring flower display brought to you by shooting star (Dodecatheon). Garden baby? Yes I think so! (I just had to show a photo of ‘the good’ before I delve into ‘the ugly’).

Then we spot those plants that fall somewhere in between… our once garden babies who have grown up, and in doing so have decided to flex their botanical muscles to power their way through the garden. Yes, I am talking about those aggressive spreaders.

Perhaps you have a patch of lily-of-the-valley (Convallaria majalis) making a run for your grass or goutweed (Aegopodium podagraria) that thinks it should be the only plant in your flower bed, or periwinkle (Vinca minor) attempting to swallow your perennials. The problem is all the same- one plant expressing it’s desire for garden dominance… otherwise known as a plant with a bad attitude.

This year, I looked out at two problem areas in my yard- both a result of neighbours’ plants thinking that the grass is greener on my side of the fence (it’s not). Couple that incorrect assumption with a few years of neglect and I’ve got myself a nice little afternoon project.

Take this lily of the valley…

How did this happen?? Oh. Right. I had kids.

or how about this goutweed…

These are two plants that spread aggressively via underground stems called rhizomes. The rhizomes grow out into new territory and sprout new plants at intervals (nodes) along the way. This means that to effectively remove plants that spread in this manner, all the underground portions need to be removed- otherwise new plants can grow and emerge from the left-over fragments. Some other plants that grow aggressively in this way include:

• Chameleon plant (Houttuynia cordata ‘Chameleon’)

• Japanese spurge (Pachysandra terminalis)

• Various mint species (Mentha spp.)

• Obedient plant (Physostegia virginiana)

• Gooseneck loosestrife (Lysimachia clethroides)

Lily of the valley and a good glimpse of it’s underground growth. Note the roots growing at intervals along the rhizome indicating the location of nodes.

So I set to work with a spade, and some elbow grease. Starting at the periphery of the problem area, I dig down, get the spade deep beneath the plants and lift them; then I gently loosen the plants from the soil by hand. Luckily my garden soil is quite sandy which makes root systems fairly easy to work out of the ground. It almost becomes a game- how long of a ‘root’ can I pull out and how many plants will be attached to it?

Goutweed and it’s underground network of roots and rhizomes.

If you garden on clay soil, or your ‘bad attitude plant’ has worked it’s way into an area containing dense fibrous root systems of other plants (such cedars or Norway maples)… I feel for you. I truly do. Your removal job becomes much much harder… sometimes even impossible. In this situation, smothering the whole patch may be your only option. This is done in three easy steps:

1. Chop the plant down to ground level

2. Lay down good quality landscape fabric over the area ensuring a sufficient overlap of adjoining pieces (at least 4 inches/10 centimeters of overlap where two fabric pieces join)

3. Cover the landscape fabric with a thick layer of mulch (3-4 inches or 7-10 centimeters)- the idea is to completely block out the sun so that the plant doesn’t even think about growing

Unfortunately the area becomes off-limits to planting until you are sure the offending plant won’t come back. The fabric and mulch should be left in place for at least a year (I would leave it for 2) at which point the landscape fabric can be removed and you can reclaim your garden territory! (It is important to note that landscape fabric is not intended to be a permanent fixture in a garden, and it’s removal is an important step! More on that in a future post.)

Take home points

If you have something that appears to be taking over your garden- first determine how it is spreading so you will know how to control it. The plant could be seeding prolifically, spreading by above-ground runners that root into the soil at intervals, or through below-ground structures such as rhizomes (the focus of this post).

At the very least, make it a yearly task to keep ‘bully plants’ in check. If you are not prepared to make the commitment to yearly maintenance, remove the plant from your garden entirely. Your ‘future self’ will thank you.

Dig deep- literally and figuratively. You will need patience to remove aggressive spreaders so harness your inner yogi and think of the process as meditative. When dealing with underground spreaders, you will also need to dig deep to see exactly what you are dealing with below the soil surface and to remove the plants effectively.

Know when to throw in the towel. As the saying goes: ‘you win some, you lose some’. Sometimes it is just easier to accept defeat and opt to smother the plants as opposed to pull them.

Avoid making the same mistake in the future. Unless you are actually looking for a plant to cover a large area, run from any plant that boasts ‘quick coverage’ or ‘fast spreading’, two terms that should be interpreted as ‘aggressive’. Oh- and if a neighbour or friend is giving away plants ‘because they have way too much’ in their garden- just smile and say ‘thanks but no thanks’.

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Seasonal Pruning for Size Control

After reading my last post, you may have been left with a burning question “don’t different trees and shrubs get pruned at different times of the year?”

The answer is yes, BUT… (and you knew that ‘but’ was coming didn’t you?) in the last post we were only discussing the removal of undesirable branches- ones that should be removed to promote good health and proper structure of our trees and shrubs. We were not discussing routine pruning for size control or rejuvenation of our plants. For this type of pruning the timing is everything… so let’s start that discussion here!

Old Wood vs. New Wood

To understand pruning times, we must first discuss the type of wood that trees and shrubs will bloom on. Let’s start with the seemingly not-so-straightforward woody plants: the ones that bloom on old wood. In these plants, flower buds were set last season and it is those buds that will bloom this year. Many of our showiest landscape plants (such as magnolias, serviceberries, dogwoods, lilacs, and rhododendrons) fall into this category, and if you look around the neighbourhood (while social distancing of course), you can often see these buds getting plump and ready for their floral frenzy.

Flower buds on a Cornus kousa (Kousa dogwood) getting ready to pop!

So what happens when you go crazy and do a size-reducing spring prune on these spring-blooming beauties? You remove all their flower buds! (The horror!) So leave these plants alone! In general, these trees and shrubs get pruned right after their bloom period has wrapped up- which also happens to be before they start setting their buds in preparation for next year’s show. So, at this point in the season, we only remove the undesirable branches. Yes, you will sacrifice some blooms by doing this, but don’t forget this is for the health and structure of the plant… we leave the size control (if necessary) for later in the growing season.

An assortment of spring beauties- none of which are pruned until after their flower show (if pruning is necessary)!

OK. So the hard part is over (phew). Let’s move on to the easy plants: trees and shrubs that bloom on new wood. These plants set their buds and bloom on those buds during the same growing season. Because these plants have quite the ‘to do’ list to accomplish before they can actually show-off their blooms, these plants are generally summer-flowering (at the earliest). For these trees and shrubs, the time to prune is now! Seize the day and prune away! No time like the present… OK you get the picture. Some common examples of these plants include:

• Hydrangea arborescens (such as the common ‘Annabelle’ hydrangea); shown below

• Hydrangea paniculata (such as the common ‘Grandiflora’ or Pee Gee hydrangea)

• Buddleia spp. (butterfly bush); shown below

• Caryopteris incana and Caryopteris x clandonensis (bluebeard); shown below

• Hibiscus syriacus (rose of Sharon)

Hydrangea arborescens still standing in the spring with it’s pretty dried flowers that provided some interest in the garden over the winter months (left) and another patch of H. arborescens that has been cut down for the spring (right, foreground). This patch is located in a common area so tending to these plants is not really an option for me, but if it were, I would be inclined to prune these shrubs back even further- cutting each stem just above a pair of buds located 10-20 cm up from ground level (oh, and I would remove all the leaves caught up in the base of the plants too!)

A Buddleia (butterfly bush) before and after pruning. Yes they get pruned HARD; pruned down to about 20-30 cm (8-10 in) with all weak growth removed. The photo on the right shows the shrub after some additional branches were removed to achieve a more uniform distribution of branches.

Spring pruning of Caryopteris incana ‘Jason’ (Sunshine bluebeard). Shown during it’s glory days last season (top left) and the same patch after spring pruning (top right)- not much left to see! The best way to tackle this shrub, in my opinion, is to grab a handful of branches and cut the whole thing down by half (bottom left); this removes bulk and allows you to ‘see into’ the shrub better so that the strongest stems can be selected to remain; old, weak, and dead stems can then be pruned out until you are left with a simple branching framework. The plant can then be taken down to a height of 20-30 cm (8-12 in) tall (bottom right).

And there you have it! Hopefully these last two posts have helped shed some light on the various goals of spring pruning. I will continue to provide more examples of pruning in future posts.

It’s now time to head back to the garden, secateurs in hand, and get to work on all those woody plants that flower on new wood.

Have fun and happy gardening!