A grafted tomato, cucumber or aubergine plant costs several times what a seed-grown one of the same variety does, and it is worth the extra only in particular cases: a greenhouse or polytunnel border that is reused year after year and is hard to rotate or refresh. GraftingJoining a chosen fruiting variety onto a separate rootstock, so the tree grows the fruit of one plant on the roots of another. Full definition → strengthens what happens below ground and does not protect the leaves and fruit above it from pests and diseases.
What grafting is
A grafted vegetable plant is two plants joined into one. The roots and lower stem come from a separate rootstockThe root system and lower stem a fruit tree is grafted onto, chosen to control the tree's eventual size rather than for its own fruit. Full definition → variety, chosen for vigorous roots and resistance to soil-borne problems rather than for its fruit. The top growth, which flowers and fruits, is the familiar variety (the scion), fused onto the rootstock while both are seedlings. It has nothing to do with genetic modification: it is the technique used on fruit trees, applied to annual vegetables.
Tomatoes, cucumbers, aubergines and several related crops (melons, peppers, squashes, chillies) can all be grafted. For tomatoes the rootstocks available to amateurs include Aegis F1The first-generation offspring of two specific, deliberately chosen parent plants, bred for a predictable, uniform result but not worth saving seed from. Full definition → and Estamino F1, so a grafted Sungold is Sungold fruit on one of those root systems, not a different tomato. The rootstock most commonly available to home gardeners for cucumbers is 'Triumph'. The fruit itself is the ungrafted variety's fruit.
Grafting your own is challenging: stem thickness has to match, the join has to be kept humid while it heals, and rootstock and scion need sowing at slightly different times, and the graft is kept in a propagator or under a clear bag, typically for around a week. Most gardeners buy plants ready-grafted. The widest choice of varieties and rootstocks is usually from mail-order specialists rather than a general garden centre, and popular combinations can sell out before April planting, so order earlier than you would for ordinary seedlings. Plants that arrive by post are best given a few days to settle indoors before hardening offGradually getting young plants raised indoors used to outdoor conditions over 7–14 days before planting out, so cold, wind and direct sun don't shock or damage them. Full definition →, rather than going straight into a cold greenhouse.
One limit to know before paying the premium: grafted plants are as prone to the usual above-ground pests and diseases as ungrafted ones. A grafted tomato in a damp, poorly ventilated space is as exposed to grey mould or blight as a seed-grown one beside it. The rootstock is insurance against soil-borne problems specifically.
For sowing dates, spacing and feeding once you have chosen, see the growing guides for tomatoes, cucumbers and aubergines.
The claimed benefits
The case for grafted plants comes down to a few points, all of which depend on the plant meeting soil-borne trouble:
- Vigour. A larger, more efficient root system lets the whole plant grow away faster.
- Soil-borne disease and pest resistance. Rootstocks are chosen to resist problems such as fungal wilts and nematodes that build up where the same crop is grown in the same soil.
- Earlier, heavier cropping. Some grafted plants, tomatoes among them, can crop earlier and more heavily.
- Stress tolerance. A stronger root system is cited for poor soil or a stressed growing environment.
Disease resistance can matter especially for heritage cultivarsA plant variety that arose or was bred under cultivation and is kept true by deliberate propagation, rather than a naturally occurring wild species. Full definition →, since modern cultivars have some resistance already.
Grafting compared across the three crops
| Crop | Typical claimed benefit | What backs it up | Where it matters most |
|---|---|---|---|
| Tomato | Vigour, resistance to soil-borne wilts such as fusarium and verticillium, earlier and heavier cropping | Named rootstocks for amateurs (Aegis F1, Estamino F1); some grafted tomatoes can crop earlier and more heavily | Permanent greenhouse or polytunnel borders grown in the same soil year after year |
| Cucumber | Vigour and resistance to soil-borne pests including nematodes | The rootstock most commonly available to amateurs is cucumber ‘Triumph’ | Borders reused without fresh soil between seasons |
| Aubergine | Vigour; resistance to soil-borne problems | Aubergines are available grafted, but no rootstock is named for them, so treat the benefit as plausible rather than shown | Greenhouse borders where soil problems are suspected |
Cost and care
How much more a grafted plant costs varies by retailer and crop, so compare the price on the label. If a soil-borne wilt kills or badly stunts a plant or two in your border most years, the premium can pay for itself through survival alone, whatever the yield on plants that would have thrived anyway.
Keep the graft union above soil or compost level. If the scion stem roots into the soil, the top is exposed to whatever soil-borne pathogens are there and you lose the rootstock's protection, so you have paid for an ordinary plant. Look for the healed join a few centimetres up the stem and plant with it clear of the compost, without deep-planting to encourage extra roots as you would with an ordinary tomato. Shoots that appear below the union come from the rootstock and should be removed. For the same reason, do not take cuttings from suckersA shoot that grows from a plant's roots or lower trunk, separate from the main framework, usually removed before it diverts energy. Full definition → of a grafted plant: they are the rootstock, not the named variety.
Give the vigorous root system room: a small pot or cramped border wastes much of what the premium buys.
The Scottish angle: does a shorter season change the maths?
Two arguments are made for grafting in Scotland, that a cooler climate means more disease pressure and that a shorter season makes extended cropping matter more. The first does not hold up well. Fusarium wilts are often diseases of hot weather and warm soils, and verticillium wilt shows from spring until autumn, developing rapidly in hot weather, with plants able to recover in cooler or wetter conditions. Neither is a cold-climate problem.
What is Scottish is the growing setup. Tomatoes, aubergines and cucumbers are typically grown under cover here, in a permanent greenhouse or polytunnel border reused season after season. That is the strongest case for grafted disease resistance, in preference to digging out and replacing the border soil every three to five years or rotating cropsMoving each crop family to different ground each year, on a multi-year cycle, so pests and diseases that build up in soil don't get a repeat host. Full definition → that a small plot may not manage. Fusarium spores stay in the soil for several years, and the soil should be rested from the affected plant type for at least four to five years. So the disease case in Scotland rests on how the crop is grown, not on the cold.
The season-length case is more plausible. The frost dates page puts safe planting out around mid May in most lowland areas, late May in the north-east lowlands and early to mid June on upland ground, while the first autumn frost arrives in mid to late September on upland ground and around late October in the lowlands (early November on island lowlands). A plant that reaches cropping size sooner and keeps going into a shortening autumn buys more usable weeks than the same head start would in a longer season. No source tests grafted plants against ungrafted ones in a Scottish greenhouse, so treat the size of that gain as unproven.
Who should pay the premium
Worth it:
- Growers with a permanent unheated greenhouse or polytunnel border that is not rotated or replaced each year, which is the situation the disease resistance is for.
- Gardeners who have lost plants to wilt, dieback or poor vigour and want insurance against a repeat.
- Anyone chasing earlier fruiting in a short season, though that gain is unproven here.
Not worth it:
- Growbags or fresh compost each year, which remove most of the soil-borne disease the rootstock protects against.
- Gardeners who have had no disease or vigour problems with ordinary plants.
- One or two plants grown as a hobby, where several times the cost for an uncertain gain is hard to justify against two or three ordinary plants.
Pay the premium for the border you cannot rotate, not for the variety you already grow well.
Common questions
Do grafted tomatoes taste different from ordinary ones?
No. Grafting joins a normal fruiting variety onto a different rootstock, so the fruit is the ungrafted variety’s fruit. Any flavour difference gardeners report is more likely to come from the plant’s vigour and stress tolerance affecting ripening and fruit set.
Can I graft my own tomato plants at home?
Yes, but it is challenging. Rootstock and scion need sowing at different times so the stems match in thickness, the cut and join have to be clean, and the graft needs high humidity while it heals. Most home gardeners find ready-grafted plants more reliable.
Do grafted cucumbers and aubergines need different care?
Mostly not: feeding, watering and training follow the same routine as for ordinary plants. The graft-specific rules are to keep the union above soil or compost level and to remove any shoots that appear below it.
Is it worth buying grafted plants for growbags?
Generally no. The advantages are fewer if you use containers or growbags each year, because fresh compost avoids most of the soil-borne disease build-up that rootstocks are chosen to resist.
Are grafted plants better suited to a Scottish greenhouse than an English one?
The disease case is about how the crop is grown, in a permanent greenhouse or polytunnel border, not about Scotland being cooler; fusarium and verticillium wilts are more associated with warm conditions. The season-length case is more Scotland-specific, though no source tests it.
Sources
Show the 7 sources
- RHS: Grafting vegetables: What grafting is; greater vigour and/or resistance to soil-borne diseases and pests such as nematodes; useful in greenhouse borders where fresh soil or rotation is impractical; fewer advantages with containers or growbags; Aegis F1 and Estamino F1 tomato rootstocks; cucumber Triumph; as prone to above-ground pests and diseases; home grafting challenging; heritage cultivars; earlier fruiting
- RHS: Vegetables in greenhouses: Replacing border soil every three to five years; grafted aubergines and tomatoes may help where soil problems are suspected
- RHS: Fusarium wilts: Often diseases of hot weather and warm soils; long-lived spores contaminate soil for several years; rest the soil from the affected plant type for at least 4-5 years
- RHS: Verticillium wilt: Wilting from spring until autumn, developing rapidly in hot weather; plants may recover in cooler or wetter conditions
- University of Arizona Extension: Grafting tomatoes: Deep planting is not recommended with grafted transplants because scion tissue may be exposed to soil-borne pathogens
- Johnny’s Selected Seeds: Grafted tomato plants: Keep the union above the soil; remove suckers that develop below the graft union, which are rootstock
- GrowScotland: Scottish frost dates: Regional safe planting-out and first autumn frost bands, derived from Met Office station records