A touch of frost is cue to take action

Lemon plants need to be brought indoors now.
Lemon plants need to be brought indoors now.

An early morning frost has sent the first warning shot across our bows. It was not severe enough to blacken the dahlia foliage or cause panic, but we have taken the hint and started an annual salvage operation that will continue over several weeks.

It begins with plants in large pots that were put outside in June for a long summer break in the garden or in the greenhouse.

Loquats, olives, coffee plants and citrus benefit greatly from this holiday, oranges and lemons in particular. They show their gratitude at being rescued from cold nights almost immediately by forming flower buds.

They are self-fertile, but I still offer a helping hand, covering each bloom with a watercolour brush daily.

If we used moderate heating in the large greenhouse, the lemon plants could stand in there all winter because they are capable of surviving one or two degrees of frost, but that would inhibit flower production, so their next stop is the warm conservatory to fill it with a splendid citrus fragrance.

Two 8ft-tall Arabian coffee plants are a permanent fixture in the conservatory. They too have white, highly fragrant flowers, which give way to clusters of beans every year. These can either be roasted, ground and turned into a hot drink, or sown to become new plants.

The latter option involves opening a ripened bean and harvesting the twin seeds inside. Sow 10 of these in a small pot as they germinate better as a group. Place them in a propagating frame at 20C and anticipate shoots after one month.

Thirty beans that germinated last year were potted up and have spent summer in the greenhouse. Now, we must find room in the conservatory if the resultant plants are to survive winter.

Easing up on watering and maintaining a minimum temperature of 10C should see them through.

Lifting late-flowering garden chrysanthemums and transferring them to the greenhouse border is possible now that it’s cleared of tomato plants.

We always dig up and move them under cover at this stage of the year, rather than leave them exposed to the elements and risk undoing several months of work.

Most of the border plants we grow are tough, but others sit uncomfortably on the borderline of hardiness. These are the kind that give rise for concern, and there are several ways of solving the problem.

Some are dug up with as much soil attached to the roots as possible and transferred to the cold greenhouse, packed close together in deep trays and placed in full light on the benching.

Lobelia cardinalis, verbena bonariensis and special zonal pelargoniums are treated in this way.