Las Pilitas Nursery

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Santa Margarita, CA 93453

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This website is dedicated to Bert Wilson. His genius continues to inspire us.

Companion Planting

Even in a vegetable garden, planting the right plants next to each other in a group can make a significant difference in plant health and yields.

I read in a book that some plants grow better when grown next to other plants, while other plants do poorly when grown next to the same plants. I read that tomato likes basil, Alliums (garlic, leek, onion), marigold, parsley, and coriander. So I set out to discover why. Below I have listed each plant/genus and the positive effects it confers when grown with the tomato plant.

Tomato, Solanum lycopersicon, is pollinated mostly by wind, with a little help from honeybees, stingless bees, bumblebees, and solitary bees (Klein et al. 2007). Solanum species are native mostly to the Americas.

Basil, Ocimum basilicum, an annual in the mint family, is pollinated by bees and flies (Raju, 1989), (Kuberappa et al., 2007), and supports arbuscular mycorrhiza (Wang & Qiu, 2006). Ocimum species are native to the Americas and Asia. Studies found that when basil was grown with tomato, the tomato plants were more vigorous, the tomato fruits were larger, and the tomato showed less damage by Fusarium wilt (Hage-Ahmed, Krammer and Steinkellner, 2013).

Allium species (garlic, leek, and onion) are mostly perennials, pollinated by bees and flies (Sajjad et al. 2008), (Clement et al. 2007), and also support arbuscular mycorrhiza (Wang & Qiu, 2006). This is important because arbuscular mycorrhiza helps to increase pollinator visits, they believe by way of higher nectar production, and also helps to increase yield of pollen (Gange & Smith, 2005). When Alliums (Allium ampeloprasum) were grown with tomatoes, tomato fruits were larger, tomato plants more vigorous, and Fusarium wilt disease on tomato was reduced (Hage-Ahmed & Steinkellner, 2013). Alliums are native to the Americas, Europe, and Asia.

Coriander, Coriandrum sativum, an annual herb native from Europe to Asia, is pollinated by bees, which are critical to its seed production (Klein et al. 2007). Scientists have found that coriander plants mask the scent of tomato plants, and so reduce damage to tomato by the silverleaf whitefly (Bemisia tabaci) (Togni et al. 2010).

Parsley, Petroselinum crispum var. neopolitanum, usually a biennial, is pollinated by syrphid flies, honeybees, and other bees (Burgett, 1980). Parsley is native to Europe. Parsley, in adddition to coriander, and dill, is small enough not to overpower the tomato plant, and also attracts tiny wasps, that are parasites of tomato pests (Russell, 2013)

Marigold, Tagetes species, usually annuals, native mostly to the Americas, are pollinated by bees, and flies. In one study, when marigolds were grown with tomatoes, they reduced nematodes, reduced damage by early blight, reduced whiteflies, aphids, and viruses, and increased yield of tomatoes (Zavaleta and Gomez, 1995) (Gomez-Rodriguez et al. 2003). There is conflicting evidence on the merits of marigolds to reduce pests and diseases on tomatoes and other plants. In conclusion, the factors affecting the benefits of marigold as an intercrop were: the actual species And variety of marigold used, climate, soil type, temperature, and the plants themselves (Ploeg, 2002), (Ploeg & Maris, 1999), (Motsinger, Moody & Gay, 1977).

For your backyard garden, the best way to plant may be to grow tomato interplanted with basil, garlic, leek, coriander, parsley, and a variety of marigold types, and species. For a more commercial setting, identifying the nematode species that is causing a major problem on your tomatoes, then checking which marigold variety is resistant, are the first two steps in aiding your tomato crop health and yield.

Parsley, Tomato, Onion, Basil and Coriander in a wine barrel. It was so dry this year, the wine barrel was all the water we had for a garden.....