Why cleaning the greenhouse is a horrible job but a necessary evil

If you have a greenhouse, or any structure that you're going to be overwintering plants in, your number one priority at this time is making sure it's clean.

By The Newsroom
Friday, 12th October 2018, 4:45 pm
Updated Friday, 12th October 2018, 5:08 pm
Greenhouse cleaned and emptied (apart from tomatoes).
Greenhouse cleaned and emptied (apart from tomatoes).

Not only must it be frost-free, but also pest-free – a horrible job, but a necessary evil.

My plants suffered a couple of years back from aphids overwintering in cracks and crevices, as I couldn’t get to out-of-the-way places in my packed conservatory.

Cleaned and decorated conservatory.

Here’s what you need to do to reduce the risk of pests:

1. On a mild day, take everything possible outside.

2. Scrub off any old shade paint from the summer.

3. Brush or vacuum surfaces to remove all debris.

Bananas, gingers, bird of paradise flower, exotic bulbs, geraniums and succulents back in conservatory.

4. Hose down the exterior and interior on a soaker setting, to loosen any pests/eggs and lichen.

5. Wash down glass with warm soapy water and a sponge. A breezy day will mean it dries out more quickly.

6. Spray all surfaces with Citrox, a powerful organic citrus extract disinfectant for cleaning greenhouses, pots, staging, tools, seed trays, bird feeders and bird baths.

It doesn’t harm plants and it’s effective against bacterial and fungal diseases.

7. Glass is best done with an anti-bacterial washing-up liquid – it doesn’t streak.

8. Check that all ventilation panels/windows are working.

9. Finally, check over plants that you’re overwintering carefully before bringing them in – you don’t want them to be harbouring pests.

Better to cut things like geraniums back outside first – and check pot rims and bases for hidden slugs, snails and vine weevils.


l For more information, plus cook what you grow, recipes, environmental news and more, log on to the website at www.mandycanudigit.com – which is also now smartphone friendly. You can also follow Mandy on Twitter @MandyCanUDigIt or you can like me on my Facebook page at Mandycanudigit


Move alpine troughs to a covered porch or lean-to to protect them from the rain. Pick over alpines regularly, removing debris and covering dead patches with extra grit to encourage re-growth.

Greenhouses can be insulated using plastic bubble wrap. This will cut down the heating bills, but make sure to minimise the amount of light blocked out by strips of tape etc, as the wrap itself will cut light levels.

Put cloches over tender herbs like basil, coriander, and tarragon, or pot up to move under glass. Pot up mint, chives and parsley to keep on a bright windowsill.

Plant autumn garlic, onion and shallot sets.

Replant hanging baskets with spring-flowering bulbs, winter heather, trailing ivies and spring bedding plants.

Raise patio containers on to bricks or purpose-made pot feet to avoid them sitting in water.

Digging the soil, especially bare patches or newly cultivated land, will expose pest larvae and eggs to birds, as well as clearing weeds and improving soil structure. Don’t leave soil uncovered for too long, as it runs the risk of erosion.

Check tree ties and stakes before winter gales cause damage.

Place fallen leaves on the compost heap or into separate pens for rotting down into leaf mould. Shredding leaves first with a shredder or mower will help them break down quicker.