Wednesday, 10 July 2019

Summer greenhouse

The summer greenhouse gets regular attention: daily watering; pinching out tomato plant side shoots; tying in cucumber and tomato stems as they head towards the roof; supporting pepper and aubergine plants as their fruit swell, making the plants top heavy. I find aubergines and peppers grow better for me in 8” or 9” pots; tomatoes, cucumber and melons are planted into the greenhouse border. 

Yesterday I thinned out some of the bunches of grapes, still green, which conveniently hang from parallel stems trained along the roof. It looks like a good crop this year. The variety is the well known dessert grape, Black Hamburg. 

There are automatic watering systems available whose main advantage is if you are away for a day or two. I’m not keen on overhead watering as tomato and aubergine plants are not keen on regular soaking of their foliage. There is also the risk of scorching as the water droplets act like mini magnifying glasses. A system of drip hoses feeding each pot or leaky hoses for the greenhouse beds are alternatives. 

However, I’m more than happy hand watering from a hose to the base of each plant, and as required to each pot. Regular, even watering for tomatoes in particular is important to avoid blossom end rot on the one hand, or their skin splitting on the other. The former results from under-watering and the latter from irregular watering leading to rapid expansion of the growing fruits.

I count to twenty for each plant. In my 16’x8’ greenhouse this year I have 12 tomato plants, 6 cucumber plants and 6 melon plants. That’s 8 minutes of watering the greenhouse border plants and maybe an additional 2 minutes watering the aubergine and pepper plant pots. On very hot days I might do this twice in one day.

We have started to harvest tomatoes and cucumbers on a daily basis so every visit has a reward.


  1. I have wondered about putting a irrigation system/hosepipe full of holes in the polytunnel. I bought a sprinkler from Lidl for 2 Euros and leave it for ten minutes then move it. My tomatoes seemed to prefer growing in the ground last year than growing in the pots this year. Think they can find and absorb water easier. What temperature does the glass house ge too? Polytunnels can go up to 40 degrees.

  2. It does get hot in a greenhouse Dave but I think polytunnels have higher humidity. Probably because of the much larger area of soil. I hose down the paved path when it’s very hot.

  3. Hello ... I have a question about cucumbers, if I may: I am growing them for the first time this year (outdoors, in large containers). Both vines are long and healthy, and have about 10 baby fruits on each, however, only one cucumber on one vine is actually swelling. Will the others grow bigger in due course, or am I doing something wrong? Should I try taking off some of the older baby fruits, to encourage the others to develop? The plants are kept well watered, and receive a tomato feed every 4 days or so. Hope you don't mind my asking.

    1. Hi, when there is an over abundance of fruit the cucumber plant will start to jettison some of them. They turn yellow and rot off. It’s a bit of a puzzle if they set fruit and then hardly any don’t develop at all. I wonder if you are over feeding and all the energy is going into plant growth rather than fruit. You mention they are being grown outdoors which for greenhouse varieties you might get away with in a sheltered in a good summer but they prefer the higher humidity indoors. Outdoor varieties that’s not a problem.

    2. Thank you very much for answering. I have checked the seed packet and all seems to be OK in that they are an outdoor variety, suitable for pots. It says to water and feed regularly but I will take what you say on board and lay off the food for a couple of weeks in the hope that more fruits start to swell. As of this morning, it seems that another couple are beginning to "take off" - one of which is quite an early one, right near the root of the vine - so perhaps all is not lost. In re-reading the packet, I was reminded too that male flowers were to be removed as soon as they formed, which I hadn't bothered to do till now. Quite a few male flowers have duly been removed, and I will keep fingers crossed for a change in fortunes over the coming days. Very much appreciate your input.

    3. Oh! PS. As none of the little fruits are rotting, I will leave them for now ... I have seen similar happen on my pumpkins, when only one or two grow to full size, so hopefully I will recognise if that starts to happen here.