Marigold And Tomato Companion Planting: Do Marigolds And Tomatoes Grow Well Together

Marigold And Tomato Companion Planting: Do Marigolds And Tomatoes Grow Well Together

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By: Mary H. Dyer, Credentialed Garden Writer

Marigoldsare bright, cheerful, heat- and sun-loving annuals that bloom dependably from early summer until the first frost in autumn. However, marigolds are appreciated for much more than their beauty; marigold and tomato companion planting is a tried and true technique used by gardeners for hundreds of years. What are the benefits of growing tomatoes and marigolds together? Read on to learn all about it

Planting Marigolds with Tomatoes

So why do marigolds and tomatoes grow well together? Marigolds and tomatoes are good garden buddies with similar growing conditions. Research studies have indicated that planting marigolds between tomatoes protects the tomato plants from harmful root-knot nematodes in the soil.

Although scientists tend to be skeptical, many gardeners are convinced that the pungent scent of marigolds also discourages a variety of pests such tomato hornworms, whiteflies, thrips, and maybe even rabbits!

Growing Tomatoes and Marigolds Together

Plant tomatoes first, and then dig a hole for a marigold plant. Allow 18 to 24 inches (46-61 cm.) between the marigold and the tomato plant, which is close enough for the marigold to benefit the tomato, but allows plenty of space for the tomato to grow. Don’t forget to install a tomato cage.

Plant the marigold in the prepared hole. Water the tomato and marigold deeply. Continue to plant as many marigolds as you like. Note: You can also plant marigold seeds around and between tomato plants, as marigold seeds germinate quickly. Thin the marigolds when they’re 2 to 3 inches (5-7.6 cm.) tall to prevent overcrowding.

Once the plants are established, you can water the marigold plants along with the tomatoes. Water both at the surface of the soil and avoid overhead watering, as wetting the foliage may promote disease. Watering early in the day is best.

Be careful not to overwater marigolds, however, as they are susceptible to rot in soggy soil. Allow the soil to dry between waterings.

Deadhead marigolds regularly to trigger continued blooming throughout the season. At the end of the growing season, chop the marigolds with a shovel and work the chopped plants into the soil. This is an effective way to use marigolds for nematode control.

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As vegetable gardeners we know the importance of bees to the success of garden…aka pollination. Marigolds not only attract bees but they help the to thrive and survive! BUT if you are planting marigolds in the vegetable garden as part of your bee attracting plan there are a few caveats to be aware of (I’ve learned this the hard way). Bees prefer the single-bloom varieties of marigolds over the double. Secondly I highly recommend only planting seeds or flowers grown in organic conditions the ones purchased at big-box stores contain insecticides that are bad for bees and your garden.

Marigolds in the vegetable garden, offer us so much as gardeners and homesteaders. Do you know why? Let me share the top 6 reasons you should be planting marigolds in the vegetable garden…if you aren’t already.


Carrots are great companion plants for your tomatoes. They complement each other’s growth habits and benefit each other. Tomatoes prefer the warmth and sunshine of summer while carrots prefer growing in coolers soils and weather.

The root system of carrots provides extra air circulation for the roots of your tomatoes. Carrots suppress the growth of weed and retain soil moisture because of their full foliage that provides a natural mulch.

The tomato plants shade the soil making it cooler for the carrots.

Vegetables & Fruits To Companion Plant With Tomatoes

If you are growing your tomatoes in an annual growing area, you must consider a number of different factors when choosing companion plants.

Often, it will be important to think not only about space but also about time.

You should think about whether companion plants will be grown alongside tomatoes right up until harvest, or grown as an interim crop before your tomatoes really get going.

It will also be vital to consider your crop rotation plan. What comes before and after your tomatoes is often just as important as what is planted with them.

When planning a planting layout and crop rotation plan, these are some other fruits and vegetables that you could plant alongside your tomatoes:

1. Peppers

This suggestion comes with a caveat. Some gardeners and gardening books will tell you to never plant members of the Solacaceae family together. This family includes potatoes, tomatoes and peppers.

The reasoning goes that planting these crops together can be problematic because diseases (like blight, for example) can easily spread between them.

However, bigger problems arise with diseases etc. when you grow members of this family in the same bed after one another. Growing them together, therefore, can sometimes be the better option.

By planting tomatoes and peppers together, you can move them together in a crop rotation system. This can make things easier in a smaller space.

What is more, tomatoes and peppers grow at the same time, and like similar conditions. And peppers can benefit from the shade and humidity created by the tomato plants close by.

2. Asparagus

Asparagus is one of the better known perennial vegetables. But asparagus beds can take a while to become established.

And once the asparagus has been harvested in spring, the bed may see no action for the rest of the year.

Rather than leaving the bed largely empty between asparagus harvests, it can be a good idea to plant tomatoes (and other companion plants) to take up the time and space.

3. Carrots

Carrots can also be companion planted with tomatoes and many people believe that though carrots will be a bit smaller as a result, overall yield will be improved.

Rather than planting carrots at the same time, it may be better to consider overlapping the cropping times of the plants, planting and harvesting early carrots in the tomato bed before they really take off, and perhaps adding a second crop once the tomato plants are past their best.

4. Celery

Tomatoes can also be planted in the same bed as celery without any harm to either crop. The celery may also benefit from the shade from the tomato plants.

However, I tend to fit celery in with brassicas, since the celery is said to repel the cabbage white butterfly.

And members of the cabbage family should not be grown with tomatoes.

5. Beans

Tomatoes are not a particularly nitrogen-hungry plant. They need a good boost of potassium to flower and fruit well.

But nitrogen fixing beans are generally a good plant to scatter all around your garden, and tall climbing beans can work well between and amongst cordoned tomato plants.

6. Squash

Beans are often planted alongside squash, since they are nitrogen-hungry.

These two feature in the famous companion planting combination – the ‘three sisters’ (along with corn). I would not recommend growing corn and tomatoes in the same bed.

But along with tomatoes and perhaps beans, squash could serve the same function that they do in that other guild.

Their spreading form and large leaves means they create good ground cover, reducing water loss from the site. Squash and tomatoes also require similar growing conditions, and so can work well together.

7. Cucumber (And Other Cucurbits)

Cucumbers (and other members of that plant family) can also work well with tomatoes.

They too share similar needs in terms of their environment and growing conditions.

And they, like tomatoes and beans, could also be grown up cordons or supports to make the most of a smaller growing area.

8. Garlic, Onions, Chives (and other Alliums)

Garlic, onions, chives and other alliums all work well as companions to a number of other plants.

Their strong smell can repel a range of pests that might otherwise bother your tomatoes.

9. Lettuce (or Other Low-Growing Leafy Greens)

Lettuce and other low-growing leafy greens can also be slotted into spaces between and beneath tomato plants.

They can be used to fill gaps between growing tomato plants early in the season, and to create ground cover to retain soil moisture and reduce weeds.

In summer, the shade cast by your tomato plants will also prevent lettuce from bolting and prematurely going to seed.

Best Companion Plants For Tomatoes

Amaranth is said to help repel pests by attracting predatory beneficial insects (i.e. the ones that get rid of the pests that will try to wreck your tomatoes).

Asparagus planted in close proximity to tomatoes will ward off nematodes (parasitic worms).


Basil repels insects (even fruit flies) and encourages growth, and it might even make your tomatoes taste better.

Walliser recommends beans (pole or bush beans, specifically) to lure in bumblebees to pollinate your tomatoes.

Borage repels tomato hornworms, and it improves flavor and growth.

Carrots can help to loosen the soil, meaning it holds water and stops the tomato plants from drying out. Gardening Know How recommends starting carrots when the tomato plants are small, so they grow in conjunction. The carrots will then be ready to harvest around the time the tomato plants are taking over the space.


Lettuce provides a living mulch, which helps to keep the soil cool and moist.

Radish planted around the base of your tomato plants will keep flea beetles away, Walliser says.

Other good companion plants for tomatoes include bee balm, calendula (pot marigold), celery, chives, cleome, cosmos, cucumber, garlic, lemon balm, lettuce, marigold, mint, nasturtium, onion, parsley, peas, sage and squash.

Companion planting with marigolds: myths and secrets

Published by Amber Hall on July 3, 2018 July 3, 2018

When we talk about companion planting we’re talking about a set of techniques. I’ve written a blog on effective companion planting techniques so I won’t repeat myself here.

How plants communicate with microbes – the basics!

All plants communicate with microbes using secondary metabolites some of which are excreted into the soil. These are called root exudates. They are compounds a plant excretes to attract and/or repel particular microbes. I’ve written a blog covering the basics of this science, so I won’t go into much detail here.

Understanding these basic functions is necessary when looking at companion planting. If for example we choose a companion plant for its scent shielding qualities, that plant may also excrete root exudates that repel say: other plants… or feed other pathogen microbes.

Therefore, we may us a plant’s companionship in one way and also get a result in another perhaps unexpected way. Nature is complex.

The key reason for companion planting with marigolds is usually based on root exudates and their effect on plant parasitic nematodes. I’ve written a blog on nematodes so have a read of that to understand nematode types. Most nematodes are great for gardens and plants.

Having a knowledge of plant susceptibility/resistance and types of nematodes we start to understand the importance for species specific plants for species specific problems. All plants evolve with particular antagonists. Marigolds are no exception.

Some Marigolds have effective defences against some plant feeding nematodes, others just don’t. Likewise, some plants in our gardens may attract the nematodes we want to kill with our Marigolds. So one plant may feed the nematodes and one might kill them.

However, nature is complex and the result of that scenario is likely to be more of those nematodes rather than less. I’ll tell you why in a bit.

Why Marigolds?

Many of our ancestors throughout the world grew and/or used Marigolds. Marigolds tend to have internal and external medicinal uses. They are beautiful and in some cultures they are used in religious and spiritual situations. They are also said to be good for gardens and soil.

Some horticulturalists and gardeners suggest they can be used as a sacrificial plant to attract some herbivores such as aphids. Others suggest companion planting with Marigolds to kill of nematodes in the soil. I sought to know what the science suggests.

Before we go on, I’ll link to this scientific article that covers the literature on the issue. As I have found, it suggests conflicting findings on the use of Marigolds on nematode populations. Those researchers have stated what we all know: nature is complex.

Research also shows a difference between the ways we use Marigolds and the effects on key nematodes. Do we use them as a cover crop or as a companion plant? Do we need to plant near their root zones or is digging in a dead Marigold plant enough? Is it more effective to use a spray based on steeped flowers or should we use the leaves?

Overall, it appears that marigolds hold the greatest effect when still growing. That tends to suggest companion planting with marigolds is key. However, not all marigolds are the same…

Which Marigolds do we use for which nematode?

Our environment and our soil is – or should be – a breeding ground for all types of nematodes. I’ve written a blog on the types of nematodes so check that out so we understand that most nematodes are our friends.

When we use Marigolds to reduce plant parasitic nematode numbers we’re looking for a Marigold that has the thiophene a-terthienyl secondary metabolite as a root exudate. Apparently that’s a very toxic compound. That compound can and often does detriment other microbes in the soil.

We also need to be mindful that the Marigold suppression of nematodes tends to only be effective when the soil temperature is between 10º C and 30ºC. So what do we do in winter and summer?

Well, we use organic matter in the soil and mulch on the soil to moderate soil temperatures. We also do that with water in the soil and a canopy of plants so there is no bare soil.

Also, in the colder seasons microbes tend to go to sleep. Most enter a dormancy period in the colder months. That’s why it’s important to store any Bt ( Bacillus thuringiensis) we have under 4º C until use.

I’ve looked into a number of different Marigolds and found three with very positive effects on some microbes. However before we go on, I just need to add that the science in this area is in its infancy. And, most of the research is being done on a handful of microbes that harm the agricultural industry. That’s probably less than 0.0001% of the microbe species as a whole.

1. Tagetes minuta – Stinking Roger/ Mexican Marigold

Tagetes minuta is considered to be a weed in most countries including several jurisdictions of Australia. Despite this, research conducted at the University of Florida shows that Tagetes minuta are resistant to two root knot nematodes (Meloidogne incognita and Meloidogne javanica) but susceptible to another root knot nematode (Meloidogne arenaria).

These nematodes I’ve just named are considered to be global problems and are also an issue throughout Australia. Therefore, for Australian gardens, we can see that if we plant Tagetes minuta and we have M.arenaria in our soil, we are likely to perpetuate a nematode issue. Why?

Because that Florida study showed that Tagetes minuta (Stinking Roger) is susceptible to M.arenaria root knot nematode. Being susceptible it can become a host for that nematode.

That’s why we need to know what nematode we have. Nature is complex…

Companion planting with marigolds of this type (Tagetes minuta) with tomatoes and eggplant is likely to be beneficial because both tomato and eggplant are susceptible to both M.incognita and M.javanica: and research suggests Tagetes minuta is resistant to those two root knot nematodes.

Therefore companion planting with marigolds in that scenario is likely to work.

Companion planting with Tagetes minuta have also shown suppressed number in Rotylenchulus reniformis and Tylenchorhynchus brassicae when inter-planted with tomato, eggplant, cabbage and cauliflower.

Rotylenchulus reniformis is a plant parasitic nematode that having infected a plant, the plant shows signs of water or nutrient deficiency. Apparently it’s a global problem affecting a lot of edible plants.

Tylenchorhynchus brassicae is known as the ‘stunt nematode’. She feeds on the roots of key brassicas and many other plants such as rice, tomato, eggplant etc and stunts their growth.

Another study found companion planting with Marigolds of this type effective when growing sugarbeets and perhaps also beetroot and chards. The antagonist there was Tetanops myopaeformis the Sugarbeet maggot.

Therefore, inter-planting Tagetes minuta with plants from the Solanacea and Brassica families may be effective with some root feeding nematodes.

2. Tagetes patula – French Marigold

Tagetes putulahas a sap known to irritate and burn skin. She flowers in an array of colours ranging from yellows, to oranges and maroons. A spray made of her flowers may be useful in reducing cankers, early blight, wilt, blossom end rot and even perhaps sun scald!

Like Tagetes minuta, companion planting with marigolds of this type (T. patula) can be effective against Rotylenchulus reniformis and also M. incognita and other nematodes.

An Indonesian study looked at a number of host and non-host plants and found, among other things, that the populations of plant parasitic nematode (Rotylenchulus reniformis) couldn’t develop with Tagetes patula and Tagetes erecta.

Another study found Tagetes patula effective in suppressing a lesion nematode (Pratylenchus penetrans [Cobb]). That study found an ongoing desirable effect using Tagetes patula as a cover crop and then planting strawberries. In fact, that study found the use of this plant as a cover crop more effective than soil fumigation. It is possible companion planting with marigolds of this type would also be beneficial to strawberries against that lesion nematode.

Therefore, it appears that where specific plant parasitic nematodes are problematic, cover cropping or companion planting with marigolds of this type might benefit other plants including members of the Solanacea family and also may have a positive effect with Cucurbits, Brassicas and Rosaceaes (strawberries etc).

3. Tagetes erecta – Aztec Marigold

Tagetes erecta is often regarded as a poisonous plant just like T. patula. She can cause skin rashes but what a lovely flower! She has known medicinal qualities and is also popular in gardens.

There does not appear to be as many scientific papers on this type of marigold. Most of the studies are approaching 30 and 40 years old. Some are more recent.

One study found companion planting with marigolds of this type successful in suppressing a number of different nematodes with cowpea. In fact they found the growth rates enhanced when Tagetes erecta were interplanted with cowpea.

Another study found a positive effect of a number of marigolds, including T. erecta with tomatoes. That study looked at four types of root galling nematodes. However, that study also showed a difference between cultivars of marigolds and also how one type of marigold acted as a host.

The key to reducing plant parasitic nematodes is creating a healthy soil

We’re not going to get rid of all the root feeding nematodes in the soil. Why would we want to? As Zen Master Thich Naht Hanh says: No mud, no lotus.

What we want is a healthy and diverse microbial population to keep the root feeding nematodes in check. Most of the nematodes in our soil are beneficial. Like everything, we need balance, homeostasis. This is a key message from soil microbiologist Dr Elaine Ingham.

As the research shows, companion planting with marigolds can be effective in reducing plant parasitic nematode populations. It depends on the type of marigold and also the cultivar. It also depends on the type of nematode and other factors such as soil temperature.

Unless we send a soil sample to someone like Dr Elaine Ingham or the Soil Foodweb Institute (Australia) how would we know if we have a nematode problem? How would we identify the type of nematode? There are many different types of root knot nematodes for example. Therefore by looking at the effects of a root knot nematode we still don’t know what type of root knot nematode we’re dealing with.

Are we dealing with Meloidogne incognita, Meloidogne javanica) or Meloidogne arenaria or some other species of Meliodogne….

The reality is, if we have a diverse microbe population in our soil, we’re less likely to have a plant parasitic microbe problem. A diverse microbe population would typically house plenty of omnivore nematodes and these would feast and feast if there were too many plant parasitic nematodes.

The presence of all the other microbes help to sustain a healthy plant. As my nitrogen fixing blog shows us, plants select for particular microbes. Healthy plants release exudates that attract and feed microbes beneficial to its survival. We get these results from having a healthy soil and gardening organically.

Therefore, I think companion planting with marigolds should be done with due caution. If we don’t have a plant parasitic problem, then why use a plant that could in fact cause a nematode problem?

Companion planting with marigolds can produce excellent results. This is particularly the case with susceptible plants such as tomatoes, eggplants etc as shown above. However, relying on marigolds to do the work rather than feeding the soil and the billions of microbes as nature intended, might be a bit short sighted.

Did you find this blog interesting? What are your thoughts on companion planting with Marigolds?

Watch the video: The Super Hero Spry Marigold AAS Winner Profile - A Tomato Companion: The Proof is in the Plant