For several years I have thought about grafting some tomatoes on potato plants to grow some tomtatoes* but never got round to it. Because I am a bit more organised this year and am going to grow some potatoes in bags for some extra-early-earlies I am planning to grow some tomtatoes. These are something of a novelty and many years ago, when the current fashion for growing grafted vegetable plants really began I asked the head of the leading retail seed company in the field (Suttons) if they were planning to sell them and they said no because they did not give the health or yield advantages of the plants they offered and were just a novelty. It seems that novelty is what people want and Thompson & Morgan are selling them widely this year again.
The idea is that one plant will produce a crop of both tomatoes and potatoes although, obviously, if you dig the plant up to get at your spuds you won’t get any more tomatoes! I see that in the USA the plants are being sold as ‘ketchup and fries’ plants which seems a little optimistic – a bit like calling grass the ‘beef and lamb’ plant!
Anyway, grafting of tomatoes is widespread and usually a good-fruiting variety is grafted, at the seedlings stage, onto rootstocks of a variety that doesn’t have good fruit but that is vigorous and is resistant to disease. These are widely used commercially and are now widely available to amateur gardeners where the improved vigour and crops are an advantage.
Potatoes and tomatoes are closely related, especially since tomatoes have recently been moved from their own genus (Lycopersicum) to the same as potatoes (Solanum). Closely related plants can be grafted onto one another and it is common practice with shrubs (roses are usually ‘budded’ which is a type of grafting). Cacti are often grafted too if the species is difficult to cultivate, particularly if they are very sensitive to overwatering – they are grafted onto more tolerant species – though they sometimes grow almost too well and are not quite the same as the plants in the wild.
So, it is possible to graft tomatoes onto potatoes for a bit of fun and I am having a go this year. I have the usual large number of tomatoes to grow this year though this time I am growing fewer heirlooms and more F1 hybrids and more small varieties. As for the potatoes, it is best to grow a maincrop variety because earlies mature too early and I am worried that the ‘roots’ will give up before the tomatoes have fully developed. By a strange chance circumstance I am going to try using ‘Mayan Twilight’ as the potato.
I bought these tubers last May at Garden Show Ireland ** and, to my shame, the poor things never got planted but were left in a cold shed! But I checked them last week to see if they were alive and, to my delight, they had shriveled but were covered in short shoots. The problem with using seed potatoes as the ‘stock’ (the roots that are grafted onto) is that each spud produces a number of shoots. So I pulled off all the shoots and potted these in small cell trays.
Being in small cells it will be easier to plant the potato and the tomato closely together in the pots ready for grafting, which I will explain in a few weeks when I do the job. I am pleased to report that even a few days after planting the shoots are growing away well.
You can adapt this method – taking the individual shoots off seed potatoes – on any spud – you do not have to wait a year as I did. It is handy if you only have a few seed potatoes of a particular variety. The plants need a bit more care but it is quite feasible.
‘Mayan Twilight’ is a rather strange potato with light crops of red-skinned tubers with white ‘spectacles’ around the eyes. It is a ‘phureja’ potato meaning that it has been bred from a different species to the ‘normal’ potato. The tubers have yellow flesh and a different texture and taste with a ‘umami’ flavour. They are fairly useless for boiling because they break up too much and they cook more quickly than standard potatoes but they are good for steaming and especially roasting and chips.
* It seems that Thompson & Morgan have copyrighted the name ‘TomTato’. The name has been widely used for the grafted oddity for many years so I will assume that ‘tomtato’ is still legit.