The secret with growing long vegetables is in the preparation of the growing medium.
As you are growing a carrot with a thin tap root, other than the initial 6 month fertiliser at the start of the plant, the mixture only needs to have minimal feed incorporated into it.
Our mixture consists of sieved compost and vermiculite to retain moisture. If you are able to source mycorrizhal funghi, add this to the seed at initial propagation. The seed should be planted around mid January to early February. Try growing at different stages to see how you get on.
Peter Glazebrook and Joe Atherton use the following mix
1/3rd clean garden soil, 1/4" fine-sieved, 1/3rd peat, 1/4" fine-sieved
1/6th grit sand, 1/8" fine-sieved, and
1/6th medium Perlite
Peter and Joe also add superphosphate (0-20-0) and sulphate of potash (0-0-50) and Seaweed meal
Place a pot at the end of the pipe to prevent the mixture from escaping. Cover the pipe with some tarpaulin to prevent the elements baking the mixture / washing it away.
Position the carrots into their final growing position, ideally at 45 degrees
There are two options for germinating the seeds
Sow long carrot seeds in a mixture of compost and sand. Add a very little amount of 6 month osmocote feed. Place the kitchen rolls in a 3" pot and surround the roll with compost. Place on a heated propagator / windowsill and cover with polystyrene. Plant 3 – 4 seeds per pot
Check the carrots after about 6 - 10 days. As soon as you see the seed leaves start to emerge they need to be placed into their final growing positions. At this point the tap root should be near to the bottom of the pot and ready for transplanting. If four seeds germinate, select the strongest plant two weeks after planting out
Sow seeds direct into the mixture in the pipe.
We cover our pipes with tarpaulin and this aids with the moisture retention. Some grower such as Joe Atherton uses duvets and this regulates the moisture and temperature of the growing area. You do not want the carrot to produce into a giant one so feeding is not essential. We recommend that you feed with a weak mixture of Shropshire Seaweed every 14 days (foliar feed). Do not allow the carrot to dry out as this will cause the tap root to dry out and it will take a long time for the roots to re-grow. Keep the mixture moist but do not saturate it as you want the carrot to search for the water.
Preparation for Showing
It's best not to water a few days before harvesting to allow the compost to dry out the compost. The tubes can be carefully tipped over where you will see the long tap root at the base of the tube.
Allow the compost to dry out slightly and then carefully tease away the carrot and gingerly remove the long root – We usually cut ours with a scissors. Place the root into a cardboard box in layers and head to the show.
Measuring at the Show
Below Mary and Peter Glazebrook are measuring their long vegetable. This was a picture from a UK giant Vegetable Show and was judged by Ray Davey who judged the UK Giant Vegetable Championships for several years.
Current World Records
The World's longest beetroot was grown by Joe Atherton in 2014 and measured 6.67 metres - 28.19 ft
The World's longest Carrot was grown by Joe Atherton in 2007 and measured 584cm - 19ft 2 inches
The World's longest parsnip was grown in 2014 by Joe Atherton and measured 6.281 metres - 20.6 feet