Campaign: Diary of a Giant Cabbage & Onion Grower David Thomas

Diary of a Giant Cabbage & Onion Grower

Week 31-35: July 30 - September 2

Giant Onions

The onions have plodded on through August and have remained green at their tops, but I think that the heat has been too much for them and that they have grown slowly.

Images of 3 onions grown in CANNA Coco Professional Plus showing variation in the amount of green leaves retained.

Giant Cabbage

I started adding CANNA P/K and upped the EC to 1.7 on the 1st of August. This had the effect of causing the heads to 'heart up' quickly. I now regret having done this since at the end of August the green ones started to split. It is also possible that splitting was caused by accelerated growth in response to the summer's heat. I have now stopped feeding the PK and am back on just CANNA Aqua Flores with an EC of 1.0. The red cabbage were looking ok at the end of August so hopefully, they will make it to the show, although September will be a nervous month for sure!

All cabbage are growing in DWC on CANNA Aqua Clay Pebbles Left to Right, Top to Bottom: 1) Cornish Giant Green Cabbage. 2) Kilmarno Red. 3) Mystery Red 1. 4) Mystery Red 2

Other Veg growing on CANNA Products

The cantaloupe melons in the coir are looking very well and I'm hopeful that I am heading for a personal best with the biggest one. I have marrows growing in the garden and am using the waste from the cabbage system to feed and water them. Of the 3 marrows in the patch, I have lost 1 to splitting. This is common with giant marrows as they are prone to growth spurts. If I can get one of the remaining marrows to the show, I think it will be a personal best for me. My previous best was one I grew a few years ago, which weighed in at 111lbs. The runner bean plant looks great in the bubble bucket system. I find it hard to believe that a single seed can produce such a big, strong plant. The peppers continue to grow well in the CANNA Coco Professional Plus...

Left to Right: 1) Canteloupe Melon grown in CANNA Coco Professional Plus. 2) Split marrow from this years crop. 3) Potential personal best marrow grown in CANNA Coco Professional Plus

Week 27-30: July 2 - July 29

The Weather!

July continued dry and hot just like June. We did have one wet day, but that was not enough for the normal outdoor crops and they could do with some more rain!

Giant Onions

I have lost all of my DWC onions. I believe that this was due to the feed/water being too hot during the hot weather period. I am keen to have another go at this next year with some alterations to the system. I think that the header tank needs to be buried under the earth as I have done for the cabbage, to keep it cooler. Perhaps painting the white would also help by reflecting the heat of the sun, rather than the black I am using which absorbs it and heats up the circulating water/feed reservoir. Even with the hot weather, the CANNA Coco Professional Plus grown onions do continue to develop slowly and they still have green tops. I am still feeding them at pH 5.5/EC 1.0.

Images 1) and 2): Giant onions growing in CANNA Coco Professional Plus

Giant Cabbage

The cabbage are still looking superb! The Klimarno Red cabbage both have very large heads and the foliage also looks good. One of the mystery varieties looks as though it has the potential to overtake the Klimarno, and with 8 weeks to go, this remains a distinct possibility. The second mystery variety still looks very ordinary. The green cabbage continue to grow well with some decent hearts forming. I am now feeding them at EC 1.5 and adding some CANNA PK to the mix, in order to try to ensure the formation of a big solid, heavy heart. I am also adding CANNA BOOST and CANNAZYM. I do have a favourite cabbage in the green batch, it has a tint of red in the veins which, in my experience, usually means that it will become heavy. I now have a Bluelab pH/EC meter that will allow me to monitor the pH/EC of the water/feed solution. It is a brilliant bit of kit and very simple to use.

Top to Bottom, Left to Right. 1) Green Cabbage in deep water culture (DWC). 2) Best Green Cabbage in DWC with CANNA Clay Pebbles. 3) Klimarno Red Cabbage in DWC with CANNA Clay Pebbles. 4) Mystery Red Cabbage strain 1 in DWC. 5) Mystery Red Cabbage strain 2 in DWC with CANNA Clay Pebbles.

Other Vegetables

After losing a Coir onion, my daughter replaced it with a giant chilli pepper which is also being grown in CANNA Coco Profesional Plus. At the moment it is looking very healthy and is already sporting a pepper. My daughter has claimed rights to this, as she wants to have a go at the chilli pepper class at Malvern this year! I also have 2 cantaloupe melons growing in CANNA Coco Professional Plus. One of these has a fruit set which looks promising. I replaced the rotten cabbage with 1 runner bean plant and this has gone crazy! It has lots of flowers at the moment, but no beans yet. It will be interesting to see how well this one does.

Left to Right: 1) Runner bean in CANNA Coco. 2) Giant Chilli Pepper in CANNA Coco. 3) Canteloupe Melon in CANNA Coco.

Week 23-26: June 4 - July 1

The Weather!
This has been one of the hottest, driest Junes that we have had in a long while. There has been plenty of sunshine so all of my plants are growing well. I have opened all of the greenhouse doors, and I have left them open day and night.

Giant Onions

I have lost 2 onions during the month. The first one was a coco grown onion, which had a stuck neck, and the other was one of my deep water culture (DWC) onions, which just 'gave up' for unknown reasons. I have replaced the coco grown onion with a pepper plant which is doing well, and have put a giant cantaloupe melon in the spare DWC bin. The remaining onions look fine and have shown a lot of bulb growth in the past month. I have resisted measuring them so far!

The CANNA Coco grown onions still look quite 'happy' on an EC of 1.0, so I have not changed this. I have now switched the nutrient from CANNA Aqua Vega to Aqua Flores for the DWC system since the pH started to drop rapidly in mid June. I am interpreting this to mean that they need more phosphorus and potassium now, rather than nitrogen. The pH has stabilised since I introduced this change.

Large images 1 and 2 CANNA Coco Professional Plus grown onions. Right hand Panel top 1) Onion with 'Stuck' neck. 2) Onion with 'Stuck' neck pulled. 3 & 4 Growth of the pepper replacing the pulled onion.

Giant Cabbage

The bad news is that I have lost one green cabbage. It looked different from the rest when I planted them and, for this reason, I thought it might be worth trying it. I found out later that the reason it looked different was that it had a rotten stump! This cabbage was removed from the system and replaced with a long runner bean. It is not all bad news though as I can see a big improvement in the cabbage this year compared to last year.

They don’t droop in the hot weather this year either, and I think this is because I am keeping the water cooler. The header tank, holding 200 litres of water, is buried in the ground which buffers its temperature against the heat of the day. Next year I need to set up a similar system for my onions!

I have also changed from CANNA Aqua Vega to Aqua Flores in the cabbage system and upped the EC to 1.45, while maintaining the pH at 5.5. All of the remaining cabbage look healthy. The 5 remaining green cabbage all have equal potential and could all grow to be as big as last years best.

The red cabbage are the stars though, I have never seen red cabbage as big as these at this point in the season. They are still keeping pace with the green cabbage and, if they continue to do so, could give some very interesting weights when they hit the scales! The 2 mystery red cabbage varieties have also put on a lot of growth and show great potential. It looks as if the problem I will have come show time is which one to take? Not a bad problem to have!

Top to bottom, left to right: 1) DWC Cabbage in the polytunnel. 2) DWC Green Giant cabbage. 3) DWC Kilmarno Red cabbage. 4) Row of DWC mystery red strains. 5) DWC Mystery red strain 1, 6) DWC Mystery red strain 2.

Week 18-22: April 30 - June 3

Giant Onions

I have managed to get supports around all of my onions this month and they are all looking a lot tidier. The CANNA Coco Professional Plus grown onions are now quite a size, although I haven't yet measured their circumferences. I am still feeding at an EC of 1.0 with added CANNA RHIZOTONIC and CANNAZYM. I think the onions are looking healthier this year, compared to last, which may be due to them having a bigger root zone.

Also, the weather in May has been very good for them, with a lot of warm sunny days. I have installed a fan over the onions to keep the air moving around their aerial parts, as ventilation ensures good distribution of heat, humidity and CO2 around the leaves and should encourage growth. I am now watering the Coco grown onions four times a day, as the weather is warmer and they need more food. The DWC grown onions have their supports now and are looking superb. In fact, they seem to be catching up with the Coco grown plants which is amazing as the sowing date was a lot later. My cunning plan seems to be working so far!

I have maintained the EC at 1.0, as they seem to be happy and are growing fast, but I may increase this slightly in June. On the longest day of the year, the 21st of June, I will modify the light-dark cycle on my DWC grown onions. I will maintain the day length the same as the longest day in an attempt to encourage them to continue to produce new leaves. I don't know if anyone has ever tried this, and it may go horribly wrong, but in my mind it makes sense.

Top to bottom, left to right: 1) Coco grown onion May 13th. 2 & 3) Coco grown onions June 1st. 4) Fan used to ventilate onions. 5 & 6) DWC grown onions June 1st.

Giant Cabbage

I have planted all of this year's cabbage now, 6 green and 6 red. The 2 earlier planted red cabbage are surprising me, as they seem to be keeping pace with the green ones so far. If they continue to grow at this rate things could get very interesting for the season end shows. My two 'mystery varieties' of red cabbage are also growing well and I am excited to see how they do towards the end of the season. I increased the EC of the feed for the cabbage to 1.35 for the last 10 days of May and they seem to be fine with it.

I have set up the feeding system for the cabbage to run autonomously again this year. I am hoping that this will reduce the guesswork involved in my growing. The header tank holds 1000-litres of water and it would seem a waste to dump it all each week. It is also time-consuming to completely refill the header tank so I am pumping some of it out every day and using it to water my greenhouse. My tomatoes (normal ones, not giants) now look great as well!

Top to bottom, left to right: 1) Red and Green cabbage in the polytunnel early May. 2) DWC Red cabbage root system early May. 3) Red cabbage in situ in DWC early May. 4) Red Cabbage end of May. 5) Green Giant in DWC end of May. 6) Red cabbage in DWC at same age as the Green Giant.

Week 14-17: April 2 - April 29

Giant Onions

My CANNA Coco Professional Plus grown onions are looking very well, I’m keeping the EC at 1.0 and the pH at 5.5, as previously. I am also adding CANNA RHIZOTONIC for the roots. The onions are being watered once a day (in the morning), but I plan to increase this as the weather gets hotter and the onions get bigger. At the moment each onion plant has up to 10 leaves which is about the same as at this stage last year. I think that they are appreciating the larger pots I am using this year. The DWC onions are away, but look untidy. They are being watered/fed with CANNA Aqua Vega (EC 1.0 and pH 5.5) plus some CANNA RHIZOTONIC. I need to design some supports for them as they can't hold themselves upright, which is causing some damage to the leaves. The roots look good and are getting right down into the water now.

Project 1 Onions: Above, left to right: 1) CANNA Coco onion, 2) DWC onion, 3) DWC onion roots, 4) DWC onion needing support


There has been quite a bit happening with the cabbage in April. The hydroponic system is largely up and running and I transplanted the first 8 cabbage (6 green and 2 red) into net pots on April 29th. I'm feeding them on CANNA Aqua Vega at an EC of 1.0 with the pH being kept at 5.5. I am also adding CANNA RHIZOTONIC to the feed. I am trying two new strains this year that were recommended to me as having the potential to grow very large. If they do break the World Record I will let you all know their details. Since I received the seed quite late and they are not quite ready to go into the hydroponic setup. I plan to introduce these in May and have decided not to plant any cabbage in the ground this year as not only have I run out of time but I also have great faith in the hydroponic system.

Project 2 Cabbage: Above, left to right: 1) Header tank with water pipe returns, 2) DWC Green cabbage with support frame 3) DWC Red cabbage 4) New Red cabbage strains for DWC introduction in May

The Cabbage set up consists of 12 x 80-litre dustbins set up in three rows of four. Last year I used a 20 litre header tank, but this year I have buried a 200 litre tank at the bottom of the polytunnel. I'm hoping that burying it will help to keep the water cooler and that the larger volume will help to make it easier to keep the EC and pH stable. Each bin has two aeration pipes in the bottom which are running constantly. I have a single water pump (5000 L/hr) that will keep all three rows going with a constant flow of water and nutrients. The solution is pumped to the top of each row and then makes its way back down to the header tank through each bubble bucket in the row under gravity.

Week 1-13: January 1 - April 1

I had a lot of success growing giant vegetables with CANNA in 2017. This included growing my own personal best onion in CANNA Coco Professional Plus which gained a first place prize at the CANNA UK National Giant Vegetable Show at Malvern for a giant cabbage. The cabbage was particularly rewarding, as it was grown in a Deep Water Culture (DWC) system using CANNA AQUA (Clay Pebbles, Aqua Vega/Flores). To the best of my knowledge, this is the first DWC grown cabbage to have been awarded the First prize in a national show.

Although this is my first diary entry of 2018, the work actually started in November 2017 when I seeded my new season's onions. My plan is to grow eight giant onions in Coco Professional Plus, which is fewer than last year. The reason for this is that I thought that the onion root systems might benefit from having more substrate volume so I will be using 75 L pots, rather than the 40 L pots that I used last year. I will also try four onions in DWC for the first time. Last year's cabbage had a much higher rate of growth in DWC than they did in soil and I would like to find out whether this might benefit the onions. I will also be growing twelve giant cabbage (eight green and four red) in DWC. I have sourced bigger containers for the cabbage this season as they had extensive root systems last year and I need to find out whether this might have limited their growth. With last years successes and new ideas to build on them, I'm looking forward to the 2018 season, my third season of growing with CANNA. I am also hoping that using CANNA feeds will give this years vegetables an extra boost.

Giant Onions

This season I am growing onions in two different systems. I will compare onion growth in CANNA Coco Professional (Project 1) which is the way I usually grow them, with growth in DWC (Project 2). Project 1 seeds were planted on November 14th 2017 which is the same date I seeded the previous years onions and it seemed work well. As soon as they germinated I subjected them to 24 hour lighting for 6 weeks, after which period, the supplementary lighting (regulated using a timer) was reduced to 10 hours.

Once the onions reached the 'crook stage', in other words when the first leaf was just out of the ground, they were potted up into 3.5” pots and four weeks after that they were potted-on into 1.5 L pots with wire supports. On March the 9th, they were moved to their final positions. I have added a layer of CANNA clay pebbles in the bottom of each 75 L pot to help with drainage although CANNA informed me after that this will not be necessary and will only reduce my pot size for rooting (it just seemed to be the right thing to do at the time).

I have been feeding the Project 1 onions with CANNA Coco A & B (EC 1.0, pH 5.5). I am taking a different approach with the DWC onions as I think that they will grow a lot faster. Project 2 onion seed were started much later on February 14th (also in Coco Professional Plus) and were moved up into 3.5” pots at the crook stage. These onions were exposed to 10 hours of light per day on a timer. I intend to increase this supplementary lighing period after the longest day of summer, to try to keep the onions green right up until the show. I don’t know if this will work but I think it is worth a try. I have now moved the onions into their final deep water culture buckets, where they are being fed CANNA Aqua Vega (EC 1.0, pH of 5.5).

Above, left to right: 1) Project 1 onions (75 L pots), 2) DWC system without onions, 3) DWC system with onion in place.

Giant Cabbage

The cabbage this year will all be DWC grown. The original plan was to grow eight green and four red cabbage, but that may change a little as I have been given two new red varieties to try. I broke the world record with Klimarno, but apparently, the two new varieties I have will go bigger still. It would seem rude not to try some in DWC so I will be growing two of each red variety. I started all of the seed for the DWC system on February 14th in CANNA Coco Professional Plus. I plan to move them into their final positions towards the middle of April. The weather has been terrible so far this season, with hardly a dry day. I would normally have prepared the ground to plant cabbage in the normal way by now, but I can't even get near it. Luckily the weather doesn't have to affect the planting of hydroponically grown crops, perhaps this will play to my advantage come the Autumn.

Above, left to right: 1) Top two pots: green cabbage seedlings, bottom two pots: red cabbage seedlings, Images 2 and 3 red and green cabbages just potted-on

David Thomas from Leedstown in Cornwall was born into a farming family and has been growing vegetables all of his life. In 1999 he produced a 220 lb monster pumpkin from shop-bought seed that won him the 3rd prize at the National Giant Vegetable show in Shepton Mallet. Not bad for his first season! Exposure to the vast array of giant vegetables on show cemented David's passion, but also made him realise what he was up against if he wanted to break a world record.

Especially inspired by the giant cabbage category, David sourced some Flatpol cabbage seeds (AKA 'Cornish Giant') from a local farming friend, George Rogers. David believes that this seedline is the one that is most likely to furnish him with the world record that he seeks. In the meantime, David broke his first world record at the Malvern Show in 2011, with a parsnip weighing 7.88 kg. In 2014, he beat Bernard Lavery's 1988 British cabbage record by 360 grams with a Cornish Giant weighing 56.4 kg (124.8 lbs). The world record for this category currently stands at 62.7 kilos (138 lb 3.7 oz.; Scott Rob, Alaska 2012), which means that David has something to work towards this year.

David's growing methods are evolving with his passion, and are yielding ever more impressive results. Tangible evidence of this arrived in 2015 with a world record cucumber of 12.9 kg (23 lb 7 oz.) and again in 2016 with a 23.2 kg (51 lb 2.4oz.) red cabbage, which smashed the previous record held by R. Straw since 1925 (19.05 kilo; 42lb).

In 2017 David had a great deal of success using CANNA products, with a personal best onion grown in CANNA Coco professional plus and a first prize at the Malvern Autumn Show with a 42 kg (92 lb 9.5 oz.) Cornish Giant grown in deep water culture (DWC) with CANNA AQUA nutrient and clay pebbles. This may well be the first DWC grown Cabbage to have lifted a prize at a national event. At the same show, he won first place in the category of heaviest cucumber (12.18 kg; 26 lb 13.6 oz.) and second place for heaviest Cantaloupe melon (3.74 kg; 8 lb 3.9oz.) and longest cucumber (0.857 m).

In 2018 (his third season growing with CANNA) David plans to grow 8 onions in CANNA Coco Professional Plus, although this time in 75 litre pots rather than the 40 litre pots he previously favoured. David will also grow 4 onions in a DWC system for the first time, as last seasons results with the DWC cabbage were so encouraging.

Finally, David will grow 4 red and 8 green cabbage, all by DWC method with a view to building on last years success. As per with the onions, David will also be increasing the cabbage pot volume this year.

To find out whether more root space means bigger bulbs and bigger crowns, follow David's monthly diary here.

Growing medium: CANNA Coco Professional Plus CANNA Aqua Clay Pebbles
Plant: Giant Onion x8 Giant Onion x4 Giant Red Cabbage x4 Giant Green Cabbage x8
Location: Polytunnel Open plan Polytunnel
CANNA Nutrient: Coco A & B (5-4-3) Aqua Vega (5-3-8) and Aqua Flores (4-4-10)

David will also be using CANNA additives (RHIZOTONIC, PK 13/14, CANNABOOST Accelerator and CANNAZYM).