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Medwyn Williams

Hello. I'm Medwyn Williams – eleven times Gold medal winner at the Chelsea Flower Show, Past Chairman of the Royal Horticultural Society Fruit Vegetable and Herb Committee and President of the National Vegetable Society.

Exhibition Celery – In need of careful attention now


If you have timed it for mid to late August then it should by now be really well grown and on at least fifteen inch collars and ready for the 18 inch ones. The attention that it needs more than anything is an adequate supply of water so that the bed is always evenly moist, even to the extent that it’s really wet.

The one vegetable that does require a fair bit of attention at this time of year is the trench or exhibition type celery. If you have timed it for mid to late August then it should by now be really well grown and on at least fifteen inch collars and ready for the 18 inch ones. The attention that it needs more than anything is an adequate supply of water so that the bed is always evenly moist, even to the extent that it’s really wet. Celery in it”s wild and natural habitat grows in marshes and bogs so it does need plenty of water to maintain good growth and to make sure that it doesn’t go to seed on you. I have set up a sprinkling system on my bed and this will be left on for a couple of hours each day to really soak the bed, particularly on hot dry days.

Hybrid Crosses

I have two of my new hybrid crosses this year in two raised beds that are two feet above the surrounding concrete paths, there are twelve plant of each variety in each bed. Both beds are quite new and have not as yet really settled down as regards the organic matter that I have introduced by way of manure and peat. They still need more time to become integrated into the bed as humus and from there on the bed can be improved annually with plenty of moisture holding material throughout the bed.

There is no doubt that the vigour in the newer hybrids in comparison to the old Ideal is plain to see, however time will tell, after we have managed to understand how it needs to be grown, whether either of these will be a permanent replacement. Currently both Starburst (Ideal crossed with Moonbeam) and Redstar (Ideal crossed with red Lathom) are looking really good with plenty of heavy petioles or stalks to be seen developing.

Blanching Material

This year I have reverted back to the use of black builders damp course as blanching material as I didn’t seem to get them blanched sufficiently last year when they were collared only with corrugated paper. Of course the black damp course on it’s own will most certainly attract the heat of the sun to it and possibly cause problems later on with the young tender heart sweating and rotting away causing the dreaded celery heart rot. I have therefore purchased a couple of rolls of the aluminium backed polystyrene material, the same as I have used with my leeks, the purpose being exactly the same, to keep the plants cool which it most certainly achieves.


Since the celery was planted a week before I left for the Chelsea flower show, it has had no liquid feed at all relying totally on the base top dressing that the bed received a week prior to planting. As I have tried my utmost this year to keep the use of pesticides to a minimum, my celery initially was troubled with the celery fly which tunnels into the foliage turning them yellow. A closer look will reveal that a section of the leaf has been parted in two and inside the yellow area there will be a small maggot that if left alone would strip the foliage off your celery plant. This pest can attack your parsnips as well being from the same umbelliferae family. I managed to control it by being vigilant and as soon as I saw a patch on the leaf I cut it out or squeezed the leaf between thumb and fore finger to kill the grub.


I am not however going to let the slugs have a field day and I have kept applying a small amount of slug pellets on a regular basis around each celery head. Of all the pests in the garden I have to say that the slug is the one that can cause more damage, often unknown to you until lifting time. Who for instance would think that a slug would like onions, well they do, as I discovered to my horror a few years ago. When I lifted my show onions, one or two had a munching hole near the bottom of the onion where a slug or two had got at them. They were hiding beneath the black and white polythene in their moist dark cosy environment during the day and popping out for a feast once it got dark. Ever since then I have regularly reverted to a sprinkling of slug pellets underneath the black and white sheet at planting time as well as a few pellets pushed under the sheeting during the growing season.


There is no doubt that celery doesn’t mind a little shade and on that basis both of beds have been positioned next to a tall Leylandi hedge that runs along one side of my garden and they certainly grow very well there. I know that Bob Herbert, a top celery grower, has constructed a tubular framework above his beds so that he can roll over some dark fine netting during the hottest days.

Watering and Preventing Celery Heart Rot

From now on my main concern will be adequate watering and the control of celery heart rot which can be so devastating, just when you possibly have the best heads ever. For the past few years I have proved that the regular use of Calcium Nitrate controls this affliction as I have staged good celery at the Chelsea flower show with no heart rot at all. Bear in mind that I was staging celery fully grow when I had only just planted out the ones for the August shows, they were grown in 7 litre pots in a warm often hot greenhouse throughout. Each head of celery were given a soaking through the rose of a watering can with diluted Calcium Nitrate, I used 7ml to 1 gallon and that is sufficient to trickle down into the heart of twelve plants. The idea is to harden up the young growing tip whilst at the same time maintaining strong growth. I will apply this dose from now to show time every ten days or so depending on the weather.


Growing Parsnips

25th July 2007 I am often asked what is the best method of growing both long carrots and parsnips for the show

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