Greenhouse Growing Tips: September Edition

September is a busy time for greenhouse growing as now is the time to start preparing for the winter. As the nights draw in and the temperatures fall, the greenhouse comes into its own as a protected space to overwinter more delicate plants and grow winter crops for the kitchen.

September greenhouse growing tasks

Swap out your vegetables

The tomatoes and cucumbers are still growing but nearing the end of their season, so watering can be reduced but don’t let the compost dry out. Put chillies and peppers in the sunniest spot in the greenhouse to make the most of the autumn sun. At the end of the month remove the cucumbers and tomatoes from the greenhouse, but place any unripe tomatoes, still on the vine, on one of the greenhouse shelves or a windowsill to ripen.

Once the tomato and cucumbers crops have been cleared from the greenhouse, remove any remaining plants to a sheltered area while cleaning is carried out.

Greenhouse maintenance

Carefully remove and wash the glass and frame with warm soapy water removing the algae, moss, and grime from your greenhouse. This will improve the growing environment for plants and let in more light. It also helps control pests and diseases too.

Before refitting the glass, rub a candle on the black and white tapes in the channels, on the aluminium lips and the bottom edge of the glass panes to help the glass sheets slide smoothly.

As we are experiencing less sunlight the shading should no longer be required. Watering is recommended in the mornings, especially if a cold night is forecast. As the temperatures are dropping at night, also remember to shut the greenhouse doors and ensure the vent is closed to help keep the warmth in.

Fuchsia and non-hardy plants

Fuchsia plants can be kept over winter in the greenhouse, but they need to be protected from the frost.

Bring in the fuchsias and non-hardy plants, but check they are free from pests before bringing in from outside. Cuttings can be taken from the fuchsias and geraniums to provide material for planting out next year.

The fuchsias and cuttings will need to be kept frost-free, but geraniums need no heat over winter. In a mild winter fleece can be wrapped around more delicate plants to protect them from frost. If the weather turns colder, a paraffin heater or a candle under a terracotta pot can be used.

Keep picking fresh herbs in the greenhouse, and mint and parsley can be potted up and should last the winter season under the protection of the glass.

Cold frames in September

September sees the weather starting to turn, so the cold frames become a sheltered spot to get plants growing for next season.

Broad bean varieties such as ‘The Sutton‘, which is a short statured variety, can be planted inside the frame.

September is also an opportunity to plant winter lettuce in a cold frame, such as ‘winter density’ for later transplanting into pots for winter salads to ensure a supply for the winter.

Turnip, spinach, beetroot, carrot and small pots of radishes can be planted, as protected by a greenhouse, they will grow faster, stronger and be healthier when planted out.

Cold frames also make an excellent sanctuary for alpines. Lay some weed suppressant matting on the earth and then put some grit on top to make an area for the alpines. Leave the roof glass closed for rain protection but leave the side glass open to allow plenty of air movement through the cold frame.

Next seasons remontant type strawberries can also be planted in pots or in the earth in a rich organic soil.

Final thoughts

We hope you enjoyed September’s edition of our greenhouse growing tips. You have any questions or need any further advice, please don’t hesitate to contact us.