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Carefully overwintering perennials ensures that they come again in spring, stronger and better than ever so that you can enjoy them for many years to come. And perennial chrysanthemums are no different.
We discuss how to overwinter mums both in place in the garden and also in a storage shed, greenhouse or conservatory. And it’s not just the perennial mums that benefit from overwintering. You can change some chrysanthemums sold as annuals into perennial ones by carefully looking after them in the winter too.
How to keep chrysanthemums over winter in the garden
Over-wintering your mums planted in the garden is possible if you live in a mild climate in which the temperature doesn’t drop down below -5°C. You also don’t want to experience a lot of frosty nights so although this may not be possible in some parts of the UK, think Scotland, there are many parts where overwintering them outdoors is possible, especially for those who live further south. Your mums should be of a hardy type and the soil should be well-drained, not soggy.
Even with all this going for it, it’s best to give your plant some extra protection through the cold months. Straw, woodchips and even leaves provide insulation for both the soil and the plant’s roots. Put down a thick layer of this material around the base of plants – about 8cm to 10cm – in late autumn after the ground has frozen.
How to overwinter chrysanthemums indoors
Overwintering garden mums grown in pots
If you have planted your mums in pots, you can overwinter them indoors in pots – but maybe not the same ones. The plants need to have enough space to rest comfortably and to start growing again in the spring.
Repot the plants if needed so that there’s some space around the bush and the roots. Make sure that there is plenty of drainage holes and add some compost to the soil. Trim the plant back to about 15cm.
Do all this at the first sign of frost and then bring the pots indoors. Store them in a cold (but not colder than -1°C), dry location such as a shed, garage or greenhouse. Keep the soil just lightly moist through the winter; putting organic mulch on top of the soil helps with water retention.
If you’re transitioning an annual chrysanthemum (at least ones usually sold as annuals) into a perennial one, follow this same process.
Another way to keep chrysanthemums is by taking a cutting and growing these on which you can learn about in this guide.
Lifting and over-wintering garden mums from the garden
Mums that are growing in your flower beds need to be dug up in the late autumn. Cut the branches and stems down to about 15cm and clean off all the soil from the root. Dry everything really well and then cut the roots back to 15cm or so in length.
Place the plants in seed trays or pots and cover them with soil along with rich compost. Store the trays in a cool and airy area so the plants have good ventilation and clean air. A cold greenhouse is a good location for this as is a garage. But don’t let the temperature go below about -1°C so it’s a good idea to insulate your greenhouse over winter, you can learn how to do this here. Keep the soil only slightly moist to dry; using mulch on the soil helps with this.
Our article How to prune chrysanthemums discusses how to prepare these plants for winter. You can also learn how to take a cutting from chrysanthemums in this guide