Lettuce and Pak Choi in my Winter Hydroponic Greenhouse

My second winter hydroponic setup showing my ebb and flood Pak Choi system.

My second winter hydroponic setup showing my ebb and flood Pak Choi system.

This is just a little up date to show you what I’m currently doing in the greenhouse.
With it being winter I don’t usually grow too much due to the costs of heating, This year though I decided to try and grow some plants which are hardy enough to grow over winter.
Specifically winter lettuces/pak choi/various herbs and water cress.

As you can probably see from the photo’s in this post, I’ve bubble wrapped the whole of the inside of one part of my greenhouse.

This helps to keeps the temperature within the greenhouse a degree or two higher than outside.
I do have a heater ready and set to come on if the temperature within the greenhouse does go below freezing but this so far has only come on during two days of cold weather.

To grow these plants over winter in the UK I’ve converted my two large NFT channels into simple flood and drain systems.

I’ve got two fairly small nutrient heaters turned on to keep the nutrient solution from freezing and to keep it slightly warm, This nutrient solution flows down the channels underneath the trays of plants.

A closeup of the watercress I'm growing with the continously flowing nutrient solution.

A closeup of the watercress I’m growing with the continously flowing nutrient solution.

This might help keep the plants slightly warm but the main reason for the solution to flow all the time is to trickle over the watercress you can see in the photo growing at the start of each channel.
The continously flow is required to keep the water cress growing happily, I wasn’t sure if watercress would be happy growing during winter due to the low temperatures but the plants seem to thrive.

My winter watercress/herbs and leafy lettuce ebb and flood setup

My winter watercress/herbs and leafy lettuce ebb and flood setup

In one of my channels I’ve got lot’s of trays of various leafy lettuce and herb plants all growing in a mixture of vermiculite and perlite.
To ensure the plants all are kept with enough nutrients to grow I’ve inserted a piece of polystyrene into the end the channels,
I’ve done this so the flow of the channels trickles out at the end, but allows me to use a secondary more powerful pump at certain times during the week to flood the channels.

The power of this extra pump is enough to overcome the amount that trickles out through the polystyrene, but when the pump is turned off to stop the flood of nutrient it drains out through the polystyrene quite quickly ensuring the trays of plants don’t get waterlogged.


My Pak Choi and Winter lettuce growing in my Ebb and Flood trial system over the top of my flooding converted NFT tank growing more plants and watercress.

My Pak Choi and Winter lettuce growing in my Ebb and Flood trial system over the top of my flooding converted NFT tank growing more plants and watercress.

In my second channel I am growing lot’s of individual winter lettuces, and Pak Choi Each one has been propagated in a small rockwool cube then placed in a small pot filled with perlite. As you can see from the photo’s I’ve also topped each pot with several clay pebbles to try and stop algae growth from occuring.
Again I am using the flow of water to grow water cress at the beginning of the channel and also flooding regurlarely using the same secondary pump method as the other channel.

One last thing I’m testing this winter is a small trial flood and drain clay pebble setup growing winter lettuces and pak choi, You can see this setup in the photo’s.
It’s the small white square piece of white guttering pipe which is located above the second channel.
The whole pipe is filled with clay pebbles and has had pak choi and lettuces grown in rockwool cubes placed into cuttings at the top. The whole piece of guttering is flooded every day with nutrient solution.
You might be able to see the difference in growth rate between those grown in this flooding system and the ones grown below it. It’s quite an improvement.
I will probably enlarge this system next winter so I can grow more this way over winter.

I have also started building a system based on this guttering arrangement outside on a south facing wall to carry on growing further lettuces and then switching to growing my strawberry plants outside this year, I’ll detail this new system shortly.

The Glass Greenhouse – 2004 Season

As we are currently in the process of moving house, This Greenhouse is the only one which I have to grow within this year. I have started trying all sorts of new ideas out though, And you’ll find more information about these as you read more of this page.

As you can see in the picture here we are still growing lettuces in a cold frame outside the greenhouses like we did last year. (Please see last years greenhouse post  for more details on how this system works)

This year though I had to purchase a new air pump for the system as the belows inside the old pump had split during the winter. I also purchased two new ready perforated plastic pipes to use to supply the air to the nutrients. I am also running the air pump 24 hours a day to see what effect this has.

The system with it’s new pieces and adjustments is now performing much better than last year, To see an example of this have a look at our photo’s from this season by clicking Here.

Although this photo doesn’t show it we have also wrapped parts of the Greenhouse in large bubblewrap. This is because the cucumber plants were getting burnt from the sun.

As I didn’t have much space to play with this year having only one Greenhouse I decided to try and grow the watercress outside this year.

As there is no electricity elsewhere in the garded I decided to try and use solar power, I purchased a Solar Fountain kit from a local DIY center, The kit came with a low power water pump and the solar panel you can see here.

Unfortunately due to the lack of sun in the UK the pump doesn’t run for 95% of the time which doesn’t make it much use, To fix this I decided to built a little piece of electronics consisting of a few capacitors and a timer circuit, What this basically does it charge the capacitors up using the limited solar power available and every 20 seconds pulses the pump for approximately 2 seconds. This is enough power to pump a small amount of nutrient solution up to the Watercress channel shown below.

Shown here is the Solar powered NFT watercress system, The system is made up of a nutrient container (The green box) , This contains all the nutrient solution.

The nutrient is pumped every 20 seconds for 2 seconds by the solar panel, The solution is pumped up into a piece of standard square guttering where it flows down into another piece of guttering underneath and back into the nutrient container to start the process again.

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