Drivhusklubben/Greenhouse Forum/Gewächshausclub

08 Sep 2020 14:33

Make floor heating in your greenhouse to store apples etc. frost free the entire winter

Written by: Louise Køster from Rabarbergaarden


Some of what we here at Rabarbergaarden also use the greenhouse for is winter storage. Especially this year, it has been stuffed to the brim with all kinds of garden tools, wooden boxes, and other goodies. We are in full swing with the major renovation, which will result in us opening a grocer’s, restaurant, teaching agriculture and a centre for local food development in Gribskov, Denmark. We will open in Easter 2016 and housing it all here on the farm.


Usually, we use the greenhouse for winter storage of pots, fragile herbs and budding perennials. But we also use the greenhouse to store our apples.

And now most people will say: "Well, how can you ensure that there is no frost inside the house that will damage the apples?". 

We cannot guarantee that 100%, but when we built the house, we got one of the best advice we have received in many years.

When we had to lay the pavement in the greenhouse, we dug two 4 feet concrete pipes in each corner of the greenhouse so that the top was at floor level and not covered.

The two pipes reach down to where the ground always keeps somewhere between 5-8 degrees warmth. As you know, the heat rises upwards if it is allowed, and it does so through the two pipes and it has actually ensured that there has never been frost inside the greenhouse.

There are three things that are important when storing apples.

A frost-free place is number one.

Number two is humidity. The greenhouse has the perfect humidity in terms of storing apples. If stored apples are too dry, they become wrinkly and dull. The climate in the frost free greenhouse is perfect with good humidity all winter.

To be completely safe, we cover the apple boxes with blankets. It also keeps them dark, which is the third thing that is important.

There is actually a fourth thing as well. It is quite important to look through your apple boxes once in a while to remove apples that have become bad. Apples with bumps or badness can infect the rest of the box if the bad ones are not removed.

One of the apples we store with great pleasure is Pigeon, better known as the Christmas apple.

Many think: "What on earth can you do with that small apple besides hanging it up as a decoration?". But the fact that it is a small apple makes them perfect to pickle whole. You actually pickle them just like you pickle paradise apples and use them in the same way, that is for both Christmas roasts or if you like it sweeter, summer ice cream desserts.