Pretty marigolds have been grown as natural pest control in vegetable gardens for centuries and they really are a pest control power house. Their lovely orange flowers see off all sorts of bugs from caterpillars to mosquitos and they are super easy to grow.
So in this post I will take you through everything you need to know about growing marigolds to control pests organically without toxic pesticides.
Table of Contents
How Marigolds Control Pests Organically
Marigolds are one of the most useful companion plants in your vegetable garden as they can control all sorts of pest organically in very different ways :
- Repel vegetable eating insects
- Camouflage vegetables from pests
- Keep pests like slugs off prize vegetables as a trap crop
- Attract pest predators
- Kill disease spreading nematodes.
We can also use pretty marigolds to attract pollinators all summer long.
Repelling Pests
The fragrance of marigolds naturally repels key pests including white fly, butterflies and moths whose caterpillars devour cabbages and collard greens and some beetles.
Camouflage
Marigolds can be used as camouflage to hide vegetables such as carrots from key pests. The strong fragrance of the marigolds prevents the dreaded carrot fly from picking up the gentler smell of the carrots.
Trap Crop
Marigolds can also be used as a sacrificial trap crop for slugs and snails who will eat the marigolds rather than your vegetables. As you can cram marigolds in a bit you can easily afford to lose a few.
Pest Predator Food
Natural pest predators, such as ladybirds, lacewings and hover flies who eat aphids and mites, are essential for successful organic gardening. Bright orange marigold flowers are great for attracting these predators into your vegetable garden.
Killing Nematodes
Nematodes are a worm like bug that causes disease in vegetables such as tomatoes, lettuce, carrots, peppers & potatoes. Marigolds when flowering secrete a chemical into the soil which is toxic for nematodes. However, some nematodes can be used for organic pest control themselves so as ever in the garden we have get the balance right between the two.
Attracting Pollinators
Sun loving marigolds will keep flowering all summer long and are a great way too attract pollinating bees, butterflies, ladybugs, lacewings and hover flies into backyards to pollinate flowering and fruiting vegetables such as tomatoes, peas and zucchini.
OK now we've seen all the amazing benefits of growing marigolds for organic pest control let's move on to how to grow marigolds.
- Marigold Varieties
- When To Plant Marigolds
- Best Growing Conditions
- Sowing Marigold Seeds
- Transplanting Marigolds
- Growing Marigolds In Pots
Marigold Varieties
The first thing we need to know about growing marigolds is that there are different varieties.
- French marigolds (Tagetes patula)
- African or American marigolds (Tagetes erecta)
- And pot marigolds (Calendula officinalis) which aren't actually marigolds at all!!
French marigolds are the ones that have all of those amazing organic pest control benefits. The other marigolds are lovely but won't do the trick.
Growing Marigolds From Seed
Marigolds can be grown easily from their rather wonderful seed. Ideal growing conditions for different varieties of French marigold seed vary, so do check seed packet details before buying and sowing.
When To Plant Marigolds
French marigolds are annuals. They don't like the frost and prefer a bit of warmth so sow marigold seeds outdoor :
- After your last frost date
- When daytime temperatures have reached around 65f / 18c.
In cooler climates like the UK, it is not typically warm enough until May to sow seeds outdoors. So start seeds indoors or under good cover e.g. a greenhouse in early April to plant out in May.
Best Growing Conditions
Marigolds aren't particularly fussy about soil conditions and will grow happily in typical potting compost and reasonably well drained soil.
How To Sow Marigold Seeds
Sow marigold seeds about 1cm / half an inch deep and about 2 or 3 cm / 1 inch apart. Seedlings can be thinned later.
When To Transplant Marigolds
If you've started your marigold seeds indoors or under cover you'll need to play it by ear a bit to pick to pick the right day for transplanting. French marigolds do like sunshine and don't like to be too soggy.
If you get some nice sunny warm weather in early May and it is forecast to stay get them out there but if it is cool and wet hang on for a sunnier day. If the weather is totally unpredictable transfer them to pots that you can easily cover or bring in if necessary.
How To Grow Marigolds In Pots
I am a big fan of growing companion plants such as marigolds, garlic and chives in pots as it means you can easily move them around to do pest control duty in different parts of the vegetable garden as needed.
French marigolds only grow to 20cm or so so they can be grown individually in small 15cm / 6 inch pots which you can spread around near different vegetables needing pest protection. But marigolds do also look wonderful in a big pot if you're growing vegetables like tomatoes in containers on a patio. You can fill a 45 cm / 18 inch pot with 5 or so French marigold plants.
Where To Plant Marigolds In Your Vegetable Garden
To get the full benefit of their organic pest control powers you need to plant marigolds in a range of places around your vegetable garden.
Vegetable Bed Perimeters
Planting marigolds around the perimeter of your vegetables can help repel pests generally and act as a trap crop for slugs and snails who will hit the marigolds first and not bother with anything else.
Interplanted
To camouflage your carrots you really need to interplant marigolds in between rows of carrots so the marigold fragrance fully hides the carrots from the carrot fly.
Co-planted In Pots
If you want to use marigolds as organic pest control for nematodes on pot and container grown vegetables e.g. e.g. tomatoes, you will need to plant the marigolds in the same pot.
Do Marigolds Always Need Full Sun?
French marigolds do thrive in full sun which is great for some summer vegetables but obviously not for vegetables that prefer some shade. However, most French marigold varieties are happy enough as long as they get some sun and their roots don't get soggy in over damp ground.
What Marigolds Should Not Be Planted Near
Most helpful companion plants have some vegetables they just don't get on with, you shouldn't for example plant garlic and chives near peas. But as far as I am aware you can grow marigolds with everything without ill effect and can really use them to bring some beautiful colour into your vegetable garden and get that country cottage look that so many of us - and pollinators - love so much.
How To Keep Marigolds Flowering
If you deadhead your marigold flowers as soon as they start to fade, you can keep your marigolds flowering and doing their work attracting pollinators and pest predators all summer long.
Do Marigolds Come Back Every Year?
French marigolds are annuals so they do not come back every year and you will need to sow them again. But if at the end of the summer you let the flowers go to seed rather than deadheading them you can collect the seeds to plant next year.
And there you go, everything you need to know about growing marigolds to control pests organically. They truly are one of the most hard working companion plants and an absolute joy to see in the vegetable garden.
For more simple tips check out my other grow your own posts and follow me on Pinterest.
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