Cold Frames and a Strawberry Cage

Charlie was not asked to pose. He inserted himself into my picture!

A life restricted to home and garden has made for a spring filled with an abundance of little projects. Over the summer, I hope to share some of them with you, but for now, I want to show you the new kitchen garden with its cold frames and strawberry cage.

Looking toward the back of the yard.

A project from last year.

When a temporary shed was removed a few years ago, we began to tackle an untouched part of the backyard. Scruffy cedars were cut down for firewood and the land was levelled to make way for a pond and a large perennial garden.

My old compost bin was made using this metal bracket system from Lee Valley Tools.

Last fall all that remained was my Lee Valley compost bin, a few cedars right at the back of the house and a makeshift fence to keep the dogs in the yard. This eyesore was one of the first things you saw when you entered the main part of the garden and it has always made my cringe.

Full sun is a rare and valued commodity in my garden. The corner where the compost bin was located had sun for a good part of the day. On top of everything else, using this area to make compost seemed like a bit of a waste. So we relocated the compost bin in April and a whole new space opened up.

The old wire fence disappeared along with the last of the scruffy cedar trees. A new fence and gate were constructed using materials we had on hand (home improvement centres in Ontario were closed during the early days of COVID-19). 

Two cold frames we built never had a proper home in the garden. This corner seemed to be the perfect place to finally locate them and the new fence added in an additional layer of functionality.

We attached a teacup hook to the fence (curve up and pinched closed) and added a length of chain. On the lid of the cold frame, we attached a second teacup hook (this time curve down).

A curved metal handle makes it easy to lift the lid into the desired position. Any of the links along the chain allow you to lock the lid in place at the perfect height.

In April, when frost is likely, the lids are always closed to protect the plants inside from a possible nighttime drop in temperature. If the daytime temperature is warm, the lid can be opened enough to allow for air circulation.

We can't let young Charlie steal all the limelight.

 We added a removable shelf at the back of the cold frame. The shelf is a board that rests on two supports that run along the inside of the frame.

What are the benefits of a cold frame? 

I think of a cold frame as a greenhouse for gardeners who don't have the space or money for a full-sized structure. 

• A cold frame is basically an unheated greenhouse. Even so, the enclosed atmosphere of the cold frame is warmer than the air outside. This means you can start seedlings a few weeks earlier than you could otherwise each spring.

• A cold frame can also be used to"harden-off" plants. Once all danger of a hard frost has passed, seedlings raised inside the house can move outside to a cold frame for a short period of time while they adjust to cooler outdoor temperatures. 

Plants you typically buy in April and May have been raised inside a warm nursery, and as a result, are further along in their growth than they would be in a normal situation. I like to use my cold frame to help these early plant purchases adjust to regular temperatures. At night, I close them inside the cold frame. During the day, I crack open the cold frame so they can gradually adjust to outside temperatures. 

• A cold frame can also extend the growing season. For this, I refer to Niki Jabbour, an expert on the subject. Her book The Year Round Vegetable Gardener will teach you everything you need to know about growing vegetable crops (even in the middle of a Canadian winter).

• You can overwinter some tender plants inside a cold frame. Although they are unheated, the air inside a cold frame is much warmer than outside the enclosed environment. Last winter, I was able to keep a variegated thyme and a trailing rosemary plant alive inside my cold frame. Normally these plants would not be hardy here.

What about plans for building your own cold frame?  For this, I recommend one of the projects in Tara Nolan's book Raised Bed Revolution. The book includes a picture illustration, a plan drawing and a handy materials list.

Often you will see old windows used to make the door for a cold frame. That's fine as long as you know the paint used on the window is unleaded (old paint can flake off and fall on your food crops). 

To avoid any issues with paint, we opted for plexiglass on a simple wood frame. Cutting plexiglass is easy (simply score the plexiglass with a matt knife and then snap off the excess section).

from The Year Round Vegetable Gardener by Niki Jabbour

We used 2 x 6" pine boards to make the body of our cold frames (Note: The cold frame that Niki Jabbour typically uses sits much lower to the ground and is constructed with more weather resistant wood like cedar or redwood (see illustration above). Again refer to her excellent book on the subject for further information.)

You can plant directly into the soil inside a cold frame. At this in time, I have opted to use my frame more as a greenhouse for seed trays and potted plants. The ground at the bottom of the frame has a layer of pine bark mulch to suppress weeds.

This is the first version of our other project– the strawberry cage. 

I have tried unsuccessfully to grow strawberries in the past, but we've never enjoyed so much as a single berry. Some creature (birds, insects, raccoons or possibly rabbits) have always gotten to the strawberries first. So I came up with the idea of creating a raised bed with a  lid that was critter-proof.

We always seem to have at least one rabbit in residence. 

Again we reused materials we had on hand for the strawberry cage. Those of you who have followed this blog for years may remember our first cold frame. Each fall we transformed one of my raised beds into a cold frame. The cold frame fit together like a jigsaw puzzle and involved no permanent nails. Plexiglass doors were attached with hinges to the back of this temporary structure. I used this system for a number of years, but after a while, I wanted something more permanent.

So we took the pieces of this old jigsaw puzzle and repurposed them into the new strawberry cage.

The new strawberry cage is 6 ft long by 3 ft deep (at 3ft I can easily reach from one side of the raised bed to the other).

As with a cold frame, it is recommended that you use a weather-resistant wood like cedar or redwood for a project like this. The material we had on hand was pine, so that's what we used. It's a cheaper wood and may eventually need to be replaced. I'm okay with that.

Initially, we used a 1/4" Garden Zone Hardware Cloth for the doors that we bought at the Home Depot. While preparing for this blog post, we noticed a warning label that had previously escaped our attention "This product contains lead, a chemical known to the State of California to cause birth defects and other reproductive harm." 

What on earth is the Home Depot doing selling a garden product that may cause lead poisoning? 

Strawberry cage with the new netting.

We began an immediate search for a safer pest barrier. I settled on Chew-Proof Hardware Netting from Lee Valley Tools. It is made HDPE plastic, which is the same material they use on things like plastic milk cartons, so I figure it is pretty safe. The plastic netting isn't as aesthetically pleasing as the metal mesh, but at least it does not contain lead!

To make the cage truly practical, the doors needed to be easily propped open. They also needed to be secure enough to handle a little wind without becoming a sail. So we came up with an idea that made use of some old copper pipe that we had laying around.

My husband Harold demonstrating how we like to open the doors.

A length of copper pipe is fed through the handle on the front of the lid. The pipe makes it very easy to raise the mesh door into an upright position (of course, you can also open the door with the handle and then drop the pipe through it).

The pipe drops down through a simple tube strap on the back of the strawberry cage (the tube strap is available at any hardware store).

Detail of the pipe fed through the handle and the copper tube strap.

Here is a back view of the strawberry cage with the copper pipes in place.  I wouldn't recommend leaving the doors upright in gale force winds, but so far, they seem pretty secure.

If the doors are closed and the copper pipes are not needed, they can be neatly stored on the back of the cold frame using four broom closet clips.

Broom closet clips in detail. 

At night, I keep the doors of the strawberry cage closed. During the day, I open them so bees can pollinate my strawberry plants.

Sadly, strawberry plants disappeared quickly with the stampede of quarantine-weary-shoppers-turned would-be-gardeners this spring. I was only able to get my hands of a few decent plants. So I'm growing parsley (a personal favourite that rabbits also love to devour) alongside the strawberries. As soon as the strawberries are done, I'll probably plant some veggies like green beans.

I should also mention one key difference between this cage and a standard raised bed– the soil level must be kept low enough to give the plants the room to grow to their full height. You wouldn't want your veggies or fruit to get crushed whenever the lid is closed.

If desired, the strawberry cage could easily be transformed into a cold frame each fall– the mesh doors could be detached and plexiglass doors could be installed instead. 

As well as strawberries, I have planted a couple of compact raspberry bushes. These are mounding plants that only reach a height of 3 feet.

Bushell and Berry® Raspberry Shortcake is a dwarf, thornless raspberry variety that has a low rounded habit. This shrub is happy in both containers and rich garden soil that has good drainage. A regular deep watering each week is essential for good berry production. Fertilize with a balanced fertilizer in spring and again mid-summer. Prune only the dead canes with no fresh growth in the spring (healthy old canes carry this year's fruit). Self-pollinating. Full sun. Height: 3ft, Spread: 2 ft USDA zones: 5-9*
* When doing my research, I noted a recommendation that Raspberry Shortcake needs some winter protection for zone 5. An unheated garage or shed was suggested to provide shelter through the colder months. In spring move them outdoors when all danger of frost has passed.

To lessen the possibility the raspberries might get too dry, I opted to plant them in the ground rather than in a container. The downside of this is I will now have to worry about protecting them this coming winter.

The cold frames and the new strawberry cage are a bit utilitarian, so I had my husband make a little picket fence to help disguise the practical with a little pretty. Eventually, I hope the perennials will fill in and the clematis I planted will drape nicely over the pickets. 

So far I have planted a phlox, a purple Veronica (see above right), an Invincibelle Wee White Hydrangea (which is turning out to be more beige than the Proven Winners illustration below) and a Czechmark® Trilogy Weigela (see below) in a front of the fence.

Hydrangea arborescens 'Invincibelle Wee White'. Photo courtesy of Proven Winners 

Smooth Hydrangea, Hydrangea arborescens 'Invincibelle Wee White' is the same type of hydrangea as the classic and much-loved 'Annabelle', but in a very petite form. The flowers are cream-colored and the stems are nice and sturdy. Part sun to sun (minimum of 6 hrs. of sun) Moisture: average (Mulch recommended to help conserve water. Blooms on new wood (Prune in early spring. Cut the entire plant by one-third its total height). Height: 12 - 30 Inches, Spread: 12 - 30 Inches. USDA zones: 3-9 

Czechmark® Trilogy Weigela is a dwarf shrub that promises heavier blooming than a typical weigela. Average garden soil and moisture levels are fine for this shrub. Deer and rabbit resistant. Blooms on old wood. Full sun. Height: 36-54 Inches, Spread: 36-54 Inches. USDA zones: 4-8 

Along the tall fence at the back, I have planted a few roses, some Lamium (it self-seeds so I have plenty to spare!), a Geranium macrorrhizum (great plant for part shade) and some Pulmonaria (another self-seeder I have in abundance).

I hope to add something much taller along the fence (sunflowers or maybe some hollyhocks).

This new area also serves as a kitchen garden so I also have several pots filled with herbs. It takes me no time to whip out to this new space and pick herbs to enhance whatever I am cooking in the kitchen.

Now that this new area is largely completed, we are moving on to several other projects. There is always lots to do in a garden this size!