Griffin September Greenhouse

02 September 2022

September is a crossroad month in the greenhouse – but it all depends on the weather

By Linda Lane, Managing Director of Griffin Glasshouses

It has been an interesting summer for fruit and vegetables in the greenhouse.  Some people have had poor to moderate tomato crops and other are enjoying bumper harvests and it is the same with peppers. 

Early June was so hot that I moved the majority of aubergine plants growing in pots outside, and they are still there and cropping really well.  The six plants left growing in the greenhouse beds have fruits but only in penny numbers, yet the tomato plants and sweet peppers are fruiting fantastically well.  It was, sadly, a rubbish season for cucumbers.  The ones that did grow were delicious but there were far too few.

I can only think it was the extraordinary weather conditions that triggered these changes.  We watered and fed greenhouse plants regularly, damping down the tomato compost sometimes up to three times a day during the really hot weather.

As to giving some advice on what we do now, this is all totally dependent on the weather.  The thermometer isn’t recording that crazy hot temperatures of mid August, but it is till hot enough to need regular watering of the tomato and peppers.  The compost must not be allowed to dry out.

I’ve got some Little Gem lettuce seedlings growing and these cannot take really hot direct sun and must be kept moist.  I shall plant on in pots to grow outside but can be moved back in should the weather turn cold or excessively wet.

So, in the hot weather, keep the greenhouse windows open but beware cold winds.   If it does turn cold, close them up to retain overnight warmth but remember to open again in the morning.

Keep a watchful eye open for fungal infections and also aphids and treat accordingly.   Keep weeds under control as they will steal some of the essential water destined for the tomato and pepper plants.  A good hoe on a sunny morning should find weeds shrivelled up by the evening.

If you plan to bring frost tender plants into the greenhouse to overwinter, check them carefully whilst still outside and particularly look out for slugs and snails.  They will simply love it in your greenhouse over the cold winter months.

It is a good idea to stand over wintered plants and pots on pallets rather than directly onto soil in greenhouse beds.

Once you have cleared out the tomato and other plants, and before bringing in the more tender ones, give the inside of the greenhouse a thorough autumn clean.  Use a mild and well diluted bleach as this will deal with hidden bugs and also remove any summer build up of dirt from the glass.  Remember to wear rubber gloves and keep your eyes and skin well protected.

Personally, I am hoping for an Indian Summer through until mid or late October but, ideally, with some rain at nights.   But that’s the stuff of fairly-tales and Camelot!

Have a happy September in your greenhouse.   Linda