Look at what other people in your area are growing--or in parks or where ever. Nurseries often sell what looks good, not necessarily what will survive where you live, especially the large chain places.

& don't forget hardscape--rocks, driftwood, statuary, birdbaths, pathways & arbors, walls or fences. Then you will have something to look at in the off season. Plus it won't die!

More DIY greenhouse plans...

[thespruce.com]

I bet yu could grow peas all summer long. Peas like cold weather. So does kale. Herbs like rosemary, dill and salad burnett and chamomile make for great container plants. Forget about basil. It needs warm nights to flourish. All the herbs also make pretty flowers.

Hmmm.
It's between 0 and 10 here now (though it will get near 40 in the summer), so I imagine whatever perennials are currently coming up in my yard would work in yours?

Now blooming: forsythia, crocus, and daffodil. Now actively growing: daylily, stargazer lily, star flower, bergamot, comfrey, stone crop.

Have fun!

There are specially developed fast-growing flowers and veg you can get. My sister grows them in her short growing season in Canada. I don't know how Norway compares but I'm sure there will be something you can grow. There are nice coloured hardy shrubs you can get for winter colour.

You make me feel lucky. But fast growing annuals can be fun especially if started under cover. And many vegetables like climbing beans can be fun just to look at without the fruit.

Ask the local nurseries. They love to help, and there are also fellow gardeners who will tell you what works for them.