Tomato guild
A small group of aromatics, flowers and a trap plant to protect and boost the tomato.
The guild's plates
Introduction
The tomato guild is a small group of plants set up around the tomato to help it grow better, be less diseased and draw in more useful insects. It is organised around several roles: companion aromatics, repellent plants, attractive flowers, trap plants and ground cover.
Background
Around the tomato (the central plant) you typically find: basil and parsley (aromatics), garlic and chives (reputed repellents), borage and pot marigold (attractive to pollinators and beneficials), nasturtium (ground cover and aphid trap plant). Each plays a complementary role: protecting, drawing in beneficials, covering the soil, while also offering extra harvests.
Who this guide is for
Beginner or experienced gardeners growing tomatoes in the open ground or in a large container, on a well-lit bed of at least 1.5 m².
Why it matters
The tomato is prone to aphids, whiteflies and blight. A well-composed guild strengthens its resistance, improves pollination, draws in pollinators (bumblebees) and beneficials (hoverflies, ladybirds) and makes the bed more stable and productive, without resorting to treatments.
What to understand before starting
Detailed steps
- Step 1
Set the tomato in the centre
Plant the tomatoes in rows or clumps, 60 to 80 cm apart, with a solid stake for each plant. Full sun.
- Step 2
Add the companion aromatics
Between the tomatoes, place clumps of basil (and possibly parsley) 20–30 cm from the plants. Basil is reputed to hinder aphids and whiteflies; the idea that it improves the tomatoes' flavour is not confirmed by blind tasting (Bomford, 2004).
- Step 4
Sow borage and pot marigold
Along the outer edge or in patches between the rows, add borage and pot marigold (calendula). They draw in bees, bumblebees, hoverflies and ladybirds. (Nematode control, on the other hand, requires a dedicated, dense planting of French marigold/Tagetes over a whole season, not a few companion plants.)
- Step 5
Set the nasturtium along the edge
Right at the edge of the bed, on the path side, plant the nasturtium. It trails, covers the soil and traditionally acts as a trap plant: if it gets loaded with aphids, cut the affected stems so it does not become a hotbed.
- Step 6
Mulch the soil
Cover the bare soil with 5 to 8 cm of straw, hay or dry clippings. This limits evaporation, keeps the soil life active and stabilises the temperature around the roots.
- Step 7
Tend and adjust
Keep the bed airy. Trim the nasturtium if it takes over, remove the tomatoes' lower leaves for air circulation, and harvest regularly to stimulate production.
Concrete examples
- Small bed 1.5 × 2 m: 4 tomatoes in the centre, 4 basils interspersed, 6 garlic cloves along the inner edge, 2 borages and 2 pot marigolds scattered, 3 nasturtiums at the path-side edge.
- Large family vegetable garden: a row of tomatoes every 80 cm, basil and parsley at their feet, alternating garlic/chives along the edge, continuous flowering borders of borage + pot marigold, nasturtium at the foot of the bed.
- In a large container (60 L minimum): 1 central tomato, 1 basil, 1 pot marigold, 1 trailing nasturtium over the edges.
Common mistakes to avoid
- Planting too densely: the companions turn the bed into a humid jungle and encourage blight.
- Letting the nasturtium overrun the tomato: it is vigorous and must be trimmed regularly.
- Putting the borage too close to the tomato plants: it takes up a lot of room and can compete.
- Forgetting to mulch: the soil dries out, crusts, and the soil life dies around the guild.
- Watering the foliage at the end of the day: encourages blight. Always water at the base, in the morning.
Tips & best practices
- Keep a good permanent mulch to limit evaporation and feed the soil.
- Let a few basil and pot marigold plants go to flower: very attractive to hoverflies, whose larvae eat aphids.
- Harvest borage and comfrey (if present) to make a potassium-rich liquid feed for the tomatoes.
- Save your tomato, basil, pot marigold and nasturtium seeds: the guild becomes self-reliant over the years.
Frequently asked questions
- Does basil really improve the taste of tomatoes?
- Nothing confirms it: three years of double-blind tastings showed no consistent preference (Bomford, 2004). The pairing remains a classic: both plants like the same sun and the same soil.
- Doesn't the nasturtium draw ALL the aphids onto the bed?
- It does attract aphids, that is its traditional role as a trap plant, but its protective effect on the tomatoes has not been demonstrated. Keep an eye on it: if it gets too colonised, cut off the affected stems, or it becomes a hotbed.
- Can I make this guild on a balcony?
- Yes, in a large container with at least 60 L of soil: one tomato, one basil, a pot marigold or a compact borage, and a trailing nasturtium.
Key takeaways
- Tomato in the centre, aromatics close by, bulbs along the edge, flowers scattered, nasturtium spilling over.
- Roles: aromatic, repellent, attractant, trap plant, ground cover.
- Keep the bed airy, water at the base, mulch permanently to avoid blight.
Sources
- Bomford, M.K. (2004). Yield, pest density, and tomato flavor effects of companion planting in garden-scale studies incorporating tomato, basil, and Brussels sprout. Thèse de doctorat, West Virginia University.
- Conboy, N.J.A. et al. (2019). Companion planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne limonene. PLOS ONE, 14(3), e0213071.
- Hooks, C.R.R., Wang, K.-H., Ploeg, A. & McSorley, R. (2010). Using marigold (Tagetes spp.) as a cover crop to protect crops from plant-parasitic nematodes. Applied Soil Ecology, 46(3), 307-320.
- RHS (Royal Horticultural Society) : Vegetables in containers (rhs.org.uk/vegetables/containers)