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Spirekassen

18 Jul 2022 11:41

Roses and the greenhouse

The Greenhouse Forum has asked me for an article about roses in the greenhouse and I was instantly sceptical. I do understand the idea of early sweet-smelling roses in the greenhouse. But the thing is that it is not always a good idea in the long term. Read the article and find out why.

There are many variants of beautiful roses. The rose belongs to the genus Rosa, which has more than hundreds of species. The original wild roses originate from the northern hemisphere. Actually, old fossils of roses have been discovered. These fossils date back to about 30 million years and they originate from Alaska. Although the beautiful rose sorts that we know today have been crossed and bred.

I love to spend time in a plant nurseries and look through their selection of roses. Just as lovely as they are, just as many thorns do they have. Because roses are not just roses.

In general roses are categorized in three main types by their function.

  • Roses for cultivation outdoor
  • Cut roses
  • Roses for pots

Roses for pots are those we know from the supermarket. They are cultivated in a modern industrial greenhouse and they have been adapted to live in a greenhouse climate. Cut roses are a rose variant that are used in the industry. The roses we see in a nursery are meant to be cultivated outdoor which come in many different shapes, colours and fragrances.

 

Roses in the greenhouse

The roses that are cultivated in pots and containers can be put in the greenhouse, since they are used to this climate. These roses are produced from cuttings, and are therefore, not a hardy plant as the ones that are cultivated outdoor. So do not expect the roses in pots to survive a very cold winter.

Almost all roses that are cultivated outdoor are budded plants. A budded plant (or grafted plant) is when a bud from a rose variant is fused onto the main stem of a wild rose. In other words, the root of the roses we can buy, are actually the roots from a wild rose. Wild roses are hardy plants since it originates from Alaska, and can therefore, easily survive the winter.

Roses cultivated outdoor are designed to survive all kinds of weather. And in the greenhouse the rose will evolve quickly which means that the blooming period will come early and is short.

Roses aren’t easy…

If you wish to cultivate roses in the greenhouse, then you are also inviting pests, fungus diseases and plant viruses inside the greenhouse. Especially roses can be affected by a lot of different diseases and pests. For instance, aphids love roses. In addition, roses can risk getting mildew, grey mould and the rust fungus Phragmidium.

If you still wish to cultivate roses outdoor in the greenhouse, it is best to cultivate in large pots. This way you will get a more flexible solution. In case your roses become affected by diseases or pests, the rose can quickly be removed outside. Although roses in pots are also more vulnerable in terms of frost compared to roses that are planted directly in soil.

 

Plant the rose outside the greenhouse

If you have a greenhouse and want to cultivate roses, then the best solution is to plant the roses just outside the greenhouse. In my experience, the pests such as aphids keep to their favourite food which is for example roses. That way the aphids will not be interested to ‘visit’ your greenhouse. The rose then becomes some sort of host plant for unwanted pests that you do not want inside the greenhouse.

 

Blooming

How long a rose blooms, depends on the variant. The modern rose sorts are blooming for a longer period of time. But the warmer it is, the shorter and more intense will the blooming season be which applies to all rose sorts. Maybe the reason why the wind rose originates from the Northern Hemisphere is that roses do not necessarily thrive in a greenhouse? The greenhouse climate is too warm and the flowers will quickly begin to wither.

When you let your roses grow just outside the greenhouse, they will bloom for a long time due to the cooler climate.

 

Rose tips

Roses must be fertilized three times a year to get as many flowers as possible.

  • By the end of March when the plant is about to form buds.
  • In May before the first buds start to open.
  • By the end of June after the first flowers have bloomed.

 

Rose scent in the greenhouse

Cut roses with no stem and put them in a container with water in the greenhouse. This gives a delightful summer atmosphere and makes the greenhouse smell of roses.

Om Spirekassen

Christine Wiemann is a greenhouse grower and an agricultural technician and owner of the seed company Spirekassen. Christine is an author of several books about lifestyle, garden life and plant cultivation. Today she writes blogs and shares her knowledge and passion for greenhouses. Christine is a greenhouse expert and an ambassador for Juliana Drivhuse.

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