Action plan: Nigel Colborn’s essential jobs for your garden this week

  • Tender plants are not safe from frost outside in any region of the UK. 
  • Nigel Colborn states that annuals can be composted and discarded 
  • Expert in gardening recommends that you prepare for low night temperatures as soon as possible 


Tender plants are not safe from frost in the UK. Plants that were grown as annuals like tagetes or petunias may be composted and discarded.

There are two options if you want to grow pelargoniums or fuchsias again next year. First, pot up mature plants, remove excess growth, and then bring them into a greenhouse. They could be featured plants next year.

The second is to plant cuttings now so they can be rooted next May. Small cuttings can be used to raise most plants, except begonias. As soon as possible, gather the young shoots.

Gardening expert Nigel Colborn says tender plants are no longer safe from frost outside in any part of the UK

Nigel Colborn, gardener and expert on gardening, says tender plants are not safe from frost in any part of the UK.

Fill your seed trays and pots with quick-draining potting soil. You can also add coarse horticultural soil to improve drainage.

Make sure to remove any unopened flower buds from your cuttings. Place each cut in the compost. Water well.

If the pots are heated, cuttings will quickly root if they are placed in a propagator. You can buy one for as little as £13, but there are large and better models under £40. The compost will be kept at 20c, which is ideal for fast rooting.


Although a freeze is unlikely to occur before December, it’s still advisable to be prepared for low night temperatures. Unheated greenhouses are safe, but not frost-free. Make sure that vents and doors are tight-fitting. To cover plants at night, keep horticultural blankets handy. It will keep them about 1c to 2c warm if it is not protected. To protect roots, mulch should be placed around other plants.


Dahlias may be lifted either now or after the first frost in autumn. You can remove all the top-growth, leaving only short stumps. The tubers can also be dried.

They will also last well if they are planted in large pots and kept frost-free.

Dahlias that are left in the ground need extra protection. You can protect your Dahlias by covering them with thick mulch, such as potting medium or home-made compost.


Some of my colchicums still have a few flowers. Some of the clumps are clogged. Can I split those clumps? If so, when is it best to do this?

Dorothy James, via email. 

You can divide them but it is not a good idea. Colchicums will not be fully dormant until they reach their spring top-growth withers. They will remain dormant between then and late August. It’s best not to dig up old top-growth. Then, cut the clusters and plant bulbs 10cm (4in).