Spring Garden Clean-up Done Right

How to approach spring clean-up for maximum wildlife value

Traditional horticulture has long taught us that gardens need to be cleaned up in the fall. However, this ritual is based on nothing more than outdated aesthetic desires and has no place in a wildlife friendly garden.

If you truly want to create a safe space for wildlife in your garden then you need to take notes on how nature does things. Do you see squirrels raking leaves and cutting back plants in the fall? If not then you probably shouldn’t be doing that either!

Leaves are not litter to be picked up and old stems are not an eyesore to be cut back. Despite looking life-less, they provide important habitat that gives life to something else.

Why hold off on fall clean-up?

As winter approaches, insects adopt a variety of methods to survive the cold temperatures. Some will fly south, such as the Monarch butterfly. Some, like Bumblebees, will all die off except for the queen who needs to hunker down somewhere safe. Many insects go into a state of diapause over winter months (a fancy word for hibernation) where they use a variety of strategies to survive.

You work so hard to support butterflies and other beneficial insects through the year, so why throw them all away to the curb in yard waste bags?

Here are some of the beneficial wildlife that call a “messy” garden home over the winter:

Mourning Cloak Butterfly

Mourning Cloak butterflies are one of the first butterflies to start flying in the spring. They survive our harsh winters as adults by taking shelter in tree crevices, log/brush/rock piles and under leaves. They often emerge in early spring while there is still snow on the ground and sustain themselves on tree sap. Once they are awake for the year, they will lay the next generation of eggs on tree branches and plant stems and become adult butterflies by early summer. 

Woolly Bear Caterpillars

When temperatures begin to decline in the fall Wooly Bears seek out shelter under leaves, rocks, or in piles of wood. Here, they will spend the whole winter as a caterpillar where they survive by producing anti-freeze chemicals. You may see them wandering about on warm days in early spring but once the weather warms up for good they will resume eating for a short while then finally find somewhere to pupate.  

Black Swallowtail

Black Swallowtails will often have more than one generation every year. The caterpillars who mature later in the year will find a plant stem or branch to pupate on. Here, they will spend the winter in a chrysalis attached to plant stems and branches. A natural anti-freeze will stop them from freezing. Here they lie in wait for the warmer weather of spring when they will finally emerge as a butterfly. 

The chrysalis colour will change colour from green to brown in order to blend in to the surrounding environment. This means that gardeners who clean up too early could unintentionally be throwing black swallowtail chrysalis’s into yard waste bags!  

Eastern Tailed Blues

Caterpillars of the Eastern Tailed Blue butterfly who mature late in the fall will often hunker down in seedpods where they are protected from harsh weather and hopefully predators. In spring, they will emerge from the seed pod and find somewhere to pupate. Small spiders will also seek shelter in seed pods. Find out why spiders are important for Hummingbirds. 

Cavity Nesting Bees

About a third of all native bee species make their homes in cavities such as hollow stems. Here, they will lay their eggs, provisioning each one with a ball of pollen. When the eggs hatch into small larvae, they consume the pollen as they grow and develop.  After several weeks the larvae transform into adults and emerge from the hollow stems or other cavities. These larvae will overwinter in hollow stems to emerge once weather becomes favorable again.

Birds

Many overwintering insects don’t make it through the winter because they become food for something else! Your backyard full of fallen leaves is not a mess, but rather a buffet for birds! Expect to see Mourning Doves, American Robins, Brown Thrashers, Dark-eyed Juncos and many other birds flicking through the leaves in your garden to find proteins rich insects. The nutrition they gain from insects is much more valuable than those gained from commercial bird seed.

When to clean up:

As you can see, our gardens are anything but lifeless over the winter months, no matter how they appear! If we clean them up in the fall by removing leaves or cutting back stems,  then we are essentially reducing the amount of butterflies, moths and other beneficial wildlife we will see next year because we have just removed their winter shelter.  

So when is the best time to clean up your garden? The reality?

Never.

Often times we are told to wait until the weather warms up in the spring (10-15C is a common number) before cleaning up. The fact is that this doesn't accommodate the lifecycle of every insect. According to entomologist Doug Tallamy, this isn’t a one size fits all solution:

The problem is that each insect species requires its own species-specific temperatures to become active and one prediction of some number of days above 50 does not fit all insects. Species of moths, butterflies, bees, beetles, etc. emerge all season long; some in the spring, others in the summer and others still in the fall.

Our gardens are best left to be “messy” all year long. Cleaning them up, in reality, is an aesthetic desire and not necessary for the well-being of your garden. Remember: nobody cleans up nature yet it continues to thrive. If you absolutely must clean up, then read on to learn how to do it right.

How to clean-up while maximizing wildlife value:

Cutting back stems:

Seed heads should be left standing over winter to provide a natural seed source for seed-eating birds. Standing seed heads will also collect more snow which helps insulate your plants from cold temperatures.

When you do cut back your garden in the spring, leave stems standing to at least 1ft or 30cm high. Leaving stems at this height, will provide enough space for native bees and other insects to raise their young in. 

The part of the stems that you remove can be left right there on the ground where they will break down and feed the beneficial organisms in your soil. There is no need to cart all these clippings to the compost pile only to bring them back in the form of compost a few months later.  

If cutting back stems is unavoidable, then make sure to check them for cavity nesting bees first. Some bees make it easy to identify their nests because they cap them with leaves or mud. Some bees don’t cape their nests but will rather stand guard over them with just their heads sticking out of the entrance. 

Spring pruning:

Some shrubs are best pruned in late winter or early spring. If this is the case then keep an eye out for chrysalises and cocoons that could be attached to plant stems. If you come across one, then kindly allow it to remain intact on the shrub.

 Leave the leaves:

As a wildlife gardener I always wonder how many butterflies, moths and other beneficial critters are being “thrown away” every year in yard waste bags.

Give these beneficial critters a home by simply keeping leaves in your garden beds. Most plants will have no problem pushing their way through a couple inches of leaves come spring. In fact, raking leaves out of your bed will actually disturb the top layer of soil and encourage weeds to germinate.

 If you really need to rake leaves out of your garden then consider setting aside a “wild” space in your yard where they can be re-located to. You will with-out a doubt be creating valuable habitat.  

Brush Piles and stumps:

Don’t throw away old stumps! They can give new life to your garden by providing homes for cavity nesting bees, butterflies and more. After collecting fallen sticks from an ice storm, place them in small piles in your garden. They will be used as shelter or a variety of beneficial insects and once your plants grow up you won’t even notice the sticks are there.

Watch your step:

It is tempting to begin walking in flower beds to check on emerging plants, however this should be avoided for two reasons:

1) early spring soil is wet and wet soil compacts easily. this will lead to poor plant growth and could create undesirable conditions for ground-dwelling native bees.

2) you may be stepping on critters who have not woken up yet. If you pull back some leaves on a warm spring day, you are likely to notice a lot of critters living their lives (or dreaming of warmer weather) under the leaves such as caterpillars, spiders or pill bugs. It is a whole ecosystem under there!

Installing stepping stones will help you enjoy your garden without these unintended affects.

Conclusion:

In short, garden clean up is best postponed to late spring when the weather warms up enough to allow hibernating insects to emerge. Or better yet, don’t clean up your garden at all! Being “lazy” is one of the best ways to create habitat for beneficial critters in your yard.