Where we live can impact the crops that we can grow outside, but by creating the perfect setting for certain plants that may be too tender to grow in a chillier climate is a great option.

What is a cold frame?

A cold frame is essentially a mini greenhouse, keeping crops inside protected from breezes and cool air, whilst warming from the sun and trapping warm air to create a mini microclimate.

This makes them the perfect setting for growing tender crops such as sweet potatoes and aubergines, as well as growing more produce or flowers earlier than if they were planted and grown outside.

For the best results, position the cold frame in a post that is South or South-East facing, so they have access to sun in a sheltered spot to protect from winds.

Building a cold frame

Building your own is a great idea because you can make it the exact size to fit your plot.

You don’t need to build a base for it, instead it can be built directly on soil, as long as the area isn’t prone to getting waterlogged.

Follow this step-by-step guide to build your own cold frame:

STEP 1 – Build a frame up using 4 pieces of wood, keeping it taller at the back to allow maximum sun to get in.

STEP 2 – Then using another rectangle, cut them in half to form triangles to create a sloped effect for the lid to fit on.

STEP 3 – I created the window from Perspex, which is a bit safer with the kids around compared to glass, it’s also a cheaper option. However, if you have a redundant window, you could use this and build the rest of the frame around the size of the window.

STEP 4 – Using 7 timber battens, sandwich the Perspex between them to form the lid, screwing them together to hold them in place. By leaving one of the edges open, which will be facing downwards, it will allow water to run straight off it when it rains.

STEP 5 – Next, fix the hinges to connect the lid to the base by lining them up so that the middle of the hinge is lined up with the joint of the lid with the base and screw it in place.

Now you’ve got your cold frame, you’ve got space to grow…

Sweet potatoes

Sweet potatoes are a great crop to grow, in a sunny sheltered spot they will thrive when planted 30cm apart with moist soil. For the first month of growing, watering will be sufficient by afterwards, using a tomato feed every two weeks will benefit them.

They can take around 4 or 5 months to mature, harvesting when the leaves turn yellow and then they can be boiled, roasts or cut into chips and enjoyed for dinner.

The leaves can be cooked too and used as a substitute for spinach.


Plant aubergines out in May to June, watering regularly to keep the soil moist. Once the first fruit has set, begin feeding with a high potassium liquid fertiliser once a fortnight.

When five or six fruit have set, remove the remaining flowers. Then from July to September, they will be ready to harvest when the fruit is about 15cm long.

Cold frames can be used to harden off tender plants, provide warmth for tender crops and protect cuttings. By building your own you are cutting costs too!

Spring is here, see my post on spring pollinators:

Or check out my Pinterest board for more ideas: