No one can say quite when the first frosts will happen, but they often arrive in early November in the south
Tender summer plants, such as bananas, cannas and pelargoniums, can be quite an investment in cost and time. So it would be a pity to despatch them to the compost bin once frost has seared them – particularly as many have done remarkably well in the extra heat and light this summer.
No one can say quite when the first frosts will happen, but they often arrive in early November in the south.
Where greenhouse space is available, use bubble polythene to add insulation, make a “tent” within the greenhouse of fleece to add more shelter and, if heating is going to be used, remember that 3°C is enough.
Few people have a heated frost-free greenhouse, however – the cost of energy is just too high – and unlike in Scandinavian countries, plant hotels where we can board our plants until spring are rare.
Mostly, then we bring plants indoors, even if space can be limited, especially if we lack a conservatory. Otherwise, sheds – usually ill-lit – are used. With luck, these plants will cling to life until spring, to delight and astonish us by regrowing.
Best practice is to trim plants by about a third and position in a reasonably bright place. However, if whiteflies or fuchsia or pelargonium rust are present, the plants will just be storing trouble for later and are best discarded.
Most potted tender plants are suitable candidates, including aeoniums, bananas, bird of paradise, brugmansia, lantana and house plants such as cacti, philodendrons and succulents that have spent the summer outdoors. They need no feeding and water sparingly, as you would houseplants.
Bananas and some tender shrubs such as olives or pittosporum tobira can be left outdoors, mulched to protect roots and ideally encased in straw held in place by a cylinder of chicken netting, and given a waterproof lid of bubble polythene. Wrapping tender shrubs in garden fleece can fend off freezing winds or short-term frost.
Cannas, dahlias, gladioli, tuberous begonias and other plants that die back to a “bulb” or rootstock should be stored in frost-proof sheds. Once the top growth blackens and fades, trim to ground level and bring inside if pot-grown, or lift and place in trays and boxes filled with used potting compost to prevent freezing. They should be barely moist but not bone-dry.
Overwintering tender plants is important (Photo: Tim Sandall)
Warmth is unwelcome, as this would bring the plants back into growth, so the house is unsuitable, except perhaps where a cellar is available.
Pelargoniums are unusually obliging; they, too, can be stored in a frost-free shed. Here, the trimmed plants should be lifted, gently shaken free of soil and laid out on newspaper or hung up to dry off and become dormant. In spring, bring into light and warmth, repot and feed.
Gardeners with reasonably well-drained soil in regions without severe frosts can leave dahlias and other plants with bulbs or rootstocks in place over winter, with just a pile of coarse mulch such as bark chips to prevent freezing of the soil at root depth.
If cloches or cold frames are available, they are useful for shedding rain. Victorian gardeners would sometimes use open-fronted sheds to overwinter plants – avoiding wet roots and wind shake greatly enhances plant survival.
When all other options have been exhausted, consider leaving any unprotected plants under trees, against the house wall or on the north side of a fence or wall – with luck, these will provide enough protection for your plants to pull through.
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