This article appeared in Grow It! Magazine January 2012
Grafted vegetables cost significantly more than standard plants, but is the extra expense worth it? Angela Youngman conducted a trial last summer to find out. Here she reports on the results
In recent years seed catalogues have been offering a selection of grafted ‘turbo-charged' tomatoes. This offer is now being slowly extended to other crops such as cucumbers, peppers, aubergines and squashes. Customers taking up the offer receive young plugs that have to be grown on. But what exactly is meant by grafted vegetables? As with any other type of grafted plant, it involves joining two plant varieties together so that the weaknesses of one variety are counteracted by the strength of another.
The cultivation of grafted vegetables began in Korea and Japan during the late 1920s when watermelon plants were grafted onto a squash rootstock. The experiment's success meant that use of the technique spread to other types of vegetable. The grafting technique was seen as ideal for species that require a long growing period, as it could allow harvesting to begin earlier and last for a longer period. Of course, cultivating grafted plants requires extra expense, which means that it has been most associated with higher-value crops such as tomatoes, squash, melons and aubergines.
Today over 81% of Korean and 54% of Japanese vegetable cultivation uses grafting techniques. Commercial growers have been using the technique for over 50 years. During the past decade, the technique has begun gaining popularity in the US and in Europe for consumer use. At present, grafted vegetables can only be purchased in Britain through mail-order catalogues such as Suttons.
A grafted tomato. The rootstock gives such vigour that two leading stems can be trained in place of one
The claims made for grafted vegetables are considerable. They are said to be much stronger, easier to grow and more reliable. The fruit is of higher quality and quantity than that provided by plants grown by normal methods. Grafted vegetables tolerate a far wider range of temperatures, moisture levels, salt levels and soil-borne diseases. The plants grow better with less need for chemical fertilisers and pesticides and, overall, grafted plants possess greater disease resistance. Sometimes grafted vegetables are described as being ‘turbo-charged'. This refers to their speed of growth, which is accelerated by comparison with ordinary plants.
The cost of grafted turbo charged vegetables is much higher than comparable non-grafted plants. In 2011 Suttons were selling three ‘Conchita' potted plants for £12.99. Three non-grafted tomato plants could be obtained from nurseries at a fraction of the cost, while a packet of seed can be had for just over a £1. Buying grafted vegetables is obviously much more expensive but is it worth it? Do the claims match up with reality? I decided to find out.
| ||Did you know? |
* The first grafts were made using melons to try and overcome fungal diseases, which could decimate a crop.
* Dutch growers began grafting cucumbers soon after the War in 1947.
* In 1962 the first commercially grown grafted tomatoes appeared in Europe.
* Japanese Top Grafting is the most widely used method of grafting.
Throughout last summer I trialled a range of grafted tomato plants from Suttons, DT Brown and direct from Hishtel, a grafted vegetable breeder. The varieties were ‘Shirley' (also known as ‘Felicia'), ‘Supersteak', ‘Piccolo', ‘Sungold' and ‘Conchita'. Breeders claimed that all of these would provide much higher crops and of better quality than any non-grafted alternatives. For example, the marketing material for ‘Conchita' referred to it as having ‘huge crops on trusses bearing as many as 20 fruits'. Some samples of grafted peppers, cucumber, aubergine and squash were also grown.
One of the young grafted peppers, showing healthy, even growth
In order to monitor growth and development, non-grafted versions of ‘Conchita' and ‘Shirley' were grown alongside. It was not possible to obtain non-grafted versions of ‘Supersteak', ‘Sungold' and ‘Piccolo'. Likewise, comparable non-grafted versions of the peppers, cucumber, aubergine and squash were not available.
All the plants arrived within a few days of each other. They came as plugs, which needed to be potted up as quickly as possible. Initially all the plants were placed into a greenhouse. Re-potting was necessary within a couple of weeks as they grew quite rapidly. In June, they were ready to be transplanted again as they had outgrown their pots. This time they were placed into what was expected to be their final home for the summer. Samples were planted in the vegetable plot, in pots and in grow bags. Wherever possible, grafted and non-grafted versions of the same plant were grown side by side. All the plants were regularly fed with tomato food and sometimes with a home-made comfrey fertiliser.
Spot the difference! Non-grafted (left) and grafted tomato ‘Felicia' in July
My Norfolk garden is located in an open location with fields around, so it can get quite windy. I normally experience no problem growing tomatoes, squashes and similar vegetables in the open or in containers. As my greenhouse is unheated, I have found it very slow to grow tomatoes from seed. Consequently, harvesting usually begins around early August.
This year, there was an unexpected chilly period in early June, during which night-time temperatures dropped dramatically, though not below freezing. The temperatures were sufficiently low enough to set back plants that had been planted outside, even when covered by a cloche. This period was followed by very dry weather, periods of heavy rain, and high temperatures that were said to be warmer than those in Ibiza! July and August followed similar patterns, albeit with cooler temperatures overall.
September started cool, when temperatures dropped. I thought that this was going to be the end of the plants and began to prepare for a cold autumn – only to be surprised by an Indian summer in which temperatures rose into the high twenties.
Grow bag housed grafted and non-grafted tomato plants establishing under protection in early June
On the whole the growth of the tomatoes really astounded me. They grew much faster than I could have imagined! I was away for a few days in late July and when I came back the tomato plants seemed to have almost doubled in size. In fact, they had outgrown their stakes and were happily sprawling outwards and twining into other tomato plants. As a result I had a hurried visit to the local hardware store to buy some extra long eight-foot bamboo canes, followed by several hours disentangling the stems and tying them back in. This turned into a two person job – my husband had to be called in to help hold stems and plants.
The amount of fruit on the stems was incredible. We started harvesting fruit at the end of July and by early August each of the grafted plants were positively laden with fruit. When re-potted, we counted an average of 60 fruits per grafted plant. The lack of long periods of sunlight meant that ripening was slow and sporadic. Non-grafted tomato plants had only a small fraction of this number and were much smaller. All the non-grafted plants were quite happy with stakes of around five to six foot in length.
| ||The grafted tomatoes, here ‘Conchita', yielded a real proliferation of fruits |
As summer progressed the speed of growth slowed down (thankfully!) but fruit production continued at the same high levels. At times we were picking twice daily. Crops were still being harvested from plants growing in containers outside at the beginning of October, admittedly at the end of that Indian summer. The flavour and taste of the fruit was extremely good – sweet, juicy and pleasant.
The strength of the grafted tomatoes was quite remarkable. They even survived unexpectedly high winds that whisked the mini greenhouse away to a neighbouring field. Without the gales, which broke several stems and took off some fruit, the crops would have been even higher.
Results were much more mixed for the other grafted vegetables. Peppers grew well and were quite sturdy. The cucumbers and aubergines started well but got hit by an attack of mildew. Crops appeared quickly and then decreased. The plants did not cope so well with the sudden high and low temperatures, followed by constant cool weather. As for the squash planted out into the vegetable patch at the beginning of June, it never seemed to regain its strength after the unexpected cold snap during the early part of that month.
So what's the verdict on grafted vegetables? Peppers and tomatoes worked well. I would definitely buy grafted tomatoes and peppers again in the future, particularly tomatoes. The rootstock certainly sped up the growing and harvesting period. Three plants were certainly enough to provide enough tomatoes for my family (two children and two adults) all summer. Novice gardeners and anyone with limited greenhouse space would benefit from using grafted tomatoes.
The biggest criticism of grafted vegetables from some experienced gardeners is that as they can grow fruit from seed, why bother with something that costs so much? But what most tend to forget is that, if grown from seed, in most parts of Britain you will need a heated greenhouse. When comparing costs you have to take into account the heating costs which will continue to rise for many years. Of course, growing from seed can be somewhat of a hit and miss affair for these tender crops.
The trial worked better than I could have imagined. Grafted tomatoes are, without a doubt, worth every penny of the initial cost. The expense is balanced out by the reliability of the plants and the total yield of fruits taken. For speed of growth, disease resistance, reliability, crop size and flavour, grafted versions outperformed any other variety I have ever grown. The only word of caution would be this: make sure you have plenty of very long bamboo canes or other supports at hand. Turbo charged tomatoes live up to their name!
Find out more about the Grafting Process
View the full range of grafted vegetables from Suttons
One of the grafted aubergines in June – already a good-sized plant and ready for its final growing position