Growing Guide For An Upright Cold Frame Or Mini Greenhouse (Jan – May)

In 2017 I decided to undertake a video blog on how to use a Gabriel Ash upright cold frame.  The results were impressive with this mini greenhouse producing lots of crops.  I had some successes and some failures but overall produced lots of fresh vegetables.

The videos I produced are not limited to coldframes but can be used as a guide for anyone starting out on their greenhouse gardening journey.  I would like to mention at this stage that I am in no way a professional or trained horticulturalist, just a keen amateur.  I have tried to give clear and concise advice along the way based on my own experience and quickly researched facts prior to filming.

The following is a quick guide to the content in the first two videos in the series and some additional points to greenhouse gardening.

Winter, Snow and freezing Conditions

We have had a particularly bad winter this year with regards to snow fall all across the UK. One tip for greenhouse gardeners is to clear the snow from greenhouse roofs as soon as possible to help increase the light levels into the greenhouse.  Light levels at this time of year are very sparse and so we need to do all we can to help.

If you are overwintering tender plants then we also suggest to insulate your greenhouse or cold frame with bubble insulation.  If you have a greenhouse you might only need to insulate a partition to keep one section above freezing.  If you have access to a power supply you could add in a heater from our range.


Growing Guide For An Upright Cold Frame Or Mini Greenhouse (Jan – May)


During the winter months time in the garden is limited, so it is an ideal opportunity to look through plant and seed catalogues and plan what you want to grow in the seasons ahead.

Winter tasks

During the winter months you should only water any over wintering plants very sparsely.

First crops – Potatoes

Growing Guide For An Upright Cold Frame Or Mini Greenhouse (Jan – May)

Potatoes are a great first time crop to have a go at and should be easy to grow. In my experiment I did have limited success! (see later).  In an upright cold frame you will have enough room to start off a couple of dedicated potato sacks.

The following is a list of tasks to get your first crop growing

1. Chit your seed potatoes on a frost free window cill but ideally not in full sun. The best time to Chit is Feb – March.

2. Plant them in dedicated potato sacks and good drainage is essential

3. Good quality compost must be used to grow potatoes

4. Plant chitted potatoes in the sacks. I would suggest 3 to 5 depending on the variety

5. Cover the seed potatoes wit 3” of compost

6. Water and keep the compost damp

7. As the potatoes start to grow keep covering the new shoots with compost until they reach the top of the potato sack

8. Harvest once the plants have flowered and the stems are starting to go over.

As discussed earlier with the crops I grew we did get a small return but it was a little disappointing.   During the filming process I did have to re-locate the Upright Coldframe and I believe that some of the stems could have got damaged during the move.  We also had a particularly warm March last year and the stems got very long very quickly.  So even if I had not been moving the plants, the stems could have flopped over in the heat and got damaged.

This year I will plant some potatoes again but I will only plant 3 seed potatoes per sack and I will set up a cane support system like they use at RHS Wisley (see Image)

Growing Guide For An Upright Cold Frame Or Mini Greenhouse (Jan – May)

Sowing Seeds

In the second video I also show a variety of seed sowing techniques for various plants including Courgette ‘Black Beauty’, Kale ‘Nero di Toscana, runner beans and chilli plants.  There are a wide range of seed types and sizes and all need a slightly differing sowing method.

The following are the first two videos in the series we hope you enjoy them.

Upright Coldframe Growing Guide for January to March


The video can be found on YouTube here –

Upright Coldframe Growing Guide for March to May


The video can be found on YouTube here –