DQOTD: Perennial Fall Pruning

[Midpack]

I am pretty much an idiot when it comes to taking care of plants. But we had our landscaping completely redone this summer, so I want to take proper care of everything. The landscapers gave me some advice on fall pruning, but I don't know what to do with our existing plants. We're near Chicago.

I took the time to ID every plant I could (list below), and thought I'd just Google each one to get instructions. But for some plants, I am finding conflicting instructions! For example, we have Irises - some say cut them to the ground, others only if leaves turn brown, and still others don't trim them back at all!

Do any of you know of an online (or other) resource that can provide the best advice? I'd hate to call a landscaper to come by and tell us what to do with each and every plant...

We're planning to cut the ones in red back to 4-6 inches, and just trim dead spots off other perennials

A=Azalea​

a=Aralia Sun King?​

B=Buddleia Purple Haze​

C=Crab Apple​

D=Dogwood​

D=Dwarf Blue Spruce​

e=Hardy Asters​

F/f=Hydrangea​

G=Maiden Hair Grass​

H=Hibiscus Cherry Cheesecake​

h=Hibiscus Fantasia​

I=Iris​

J=Juniper Gold Cones​

k=Astilbe​

L=Lambs Ear​

M=Microbiota​

O=Heuchera Obsidian​

P=Pulmonaria​

R=Rhododendron​

X=Hostas​

Y=Yews​

 

[TrvlBug]

A good local nursery might be of help.

I'm on the SF Peninsula and have had the same issue. We finally put in some good landscaping about 6 years ago that I manage. Most of the books refer to frost...yeah, about 3 or so nights during the winter. I just started reading a lot and experimenting. I found that when I whack, it will grow back and if the plant dies, I replace it with a more robust one.

We did have to move/replace some plants initially. Mostly, sun loving plants that just didn't get enough sun in their location. Or shade loving plants that really didn't love the northern exposure and needed a bit more sun. Neighbors replaced their landscaping a year ago and have the landscaping company take care of it...they have had the same issue and needed to replace some of their plants that just didn't work in the particular location.

 

[cooch96]

If all your plants were done just this summer, then they're aren't very well established. I'd err on the side of doing nothing until they are more mature.

But your best bet is to go to the library. Pay attention to how the author categorizes your climate, as each seems to prefer their own alpha-numeric system. DW likes books by Ed Hume and Christopher Brickwell. She has a 2-year degree in horticulture; well versed in plants, so-so on shrubs, and bizarrely ignorant on trees.

Some of the conflicting advice is based on aesthetics. Some authors simply feel differently about how winter pruning should look.

I wish I could be more help, but there is a lot of art to landscaping and "best" practices will depend on the microclimate of your property. The good news is that the plants are trying to live and should largely take care of themselves.

 

[Amethyst]

I've grown German iris for years. You don't need to "prune" them, but you do need to remove any yellowed/brown leaves, both for looks and for sanitation. Irises are prone to infection by the iris borer, an insect. They can also suffer from fungus infections.

Their biggest enemy is dampness. They love dry, well-drained ground and sunshine.

 

[audreyh1]

I agree with the new plants don't prune advice. New plants are more vulnerable during freezes until they are well established.

Since we haven't had a freeze for the past 5 winters, our plants are blooming all year. We do a light prune in late summer because we want plenty of blooms in October and November when butterflies show up by the millions. We have been doing our winter pruning in mid to late February once we're sure there will be no hard freeze.

Roses I prune back to canes just after Xmas because they put on a lot of growth in the cooler winter months and don't wait for warmer temps.

USDA zone 9b, but it's acting more like zone 10a.

 

[splitwdw]

Midpack, You do know that all those plants aren't perennials, right? Some of those trees and shrubs, like the azalea, should be pruned after blooming in the Spring. Unless you specify your USDA zone when you Google you could get conflicting information for certain plants. The Master Gardener Volunteers usually have people take phone calls if you have gardening questions and there are usually free publications on their website too.

University of Illinois Extension

Here's a link from their website regarding pruning perennials.
To Prune or Not To Prune - Perennials - Coles County Yard and Garden - University of Illinois Extension serving Coles, Cumberland, Douglas, Moultrie and Shelby Counties

 

[Philliefan33]

Don't trim the azaleas. They would benefit if you protect them over the winter by spraying with an anti-desiccant. If the asters haven't turned brown yet, they will very soon. Go ahead and cut them back to just above ground level-- new shoots will come up next year. This year's growth does nothing but die.

 

[Dawg52]

Roses I prune back to canes just after Xmas because they put on a lot of growth in the cooler winter months and don't wait for warmer temps.

.

Glad you mentioned roses. Not sure what kind these are but I'm guessing similar to yours. You see these everywhere around here. I bought this house a year ago and was afraid to prune too much. I trimmed it down so you could see 6-8 inches of the top of the brick mail box, but in no time it filled out again. You think these can be safely pruned back further? I know very little about this stuff.

​

 

[REWahoo]

Dawg, you can probably trim those roses back at any time, but I usually wait until February to prune mine.

 

[AllDone]

Dawg, the old advice for roses was to prune them back pretty severely, to 18" or less, but the new advice is to leave them tall which results in earlier and better flowering. In other words, prune them to any size you want and they'll do quite well.

If there are some big old canes in there, you might want to take them out with a small tree saw, if necessary, because younger canes bloom better. Also, check for any canes that seem to be coming from below the knotty thing at the bottom which is the graft between the rootstock and the named variety.

Roses take pruning really well, so don't worry that you'll mess it up. As long as you don't mow them to the ground, you'll be okay.

 

[Dawg52]

Ok thanks. I'll probably trim a little more this winter. The guy across the street just had a crew trim up his stuff. He also pruned a little in early summer(mostly shrubs). Will probably do the same.

 

[splitwdw]

Here's a link for your deciduous plants.
Pruning in Winter | Chicago Botanic Garden

All of you are in different USDA zones so your info for plants in zone 9 don't apply to plants in other zones.

Dawg52, Those look like "Knock Out Roses". It's an easy grow shrub rose in maturity grow 48" X 48". The recommended distance between plants is 3 feet. They can be cut back by half each season. You don't have to deadhead because they are self-cleaning (spent flower will drop off). You can buy them at most Home Depot & Lowes stores. They don't do well above zone 5.
Philliefan, He may not have evergreen azaleas. So spraying a desiccant may not be necessary.