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Expert Tips on Growing Marigold Flowers in Australia

Marigolds are warm-weather annuals, so they should be planted in spring.

Marigolds can add a bright splash of colour to your garden during the warmer months.

They can be grown in most parts of the country except for tropical regions.

There are two common varieties that you can grow:

  1. African marigolds (Tagetes erecta) have large and bold flowers.
  2. French marigolds (Tagetes patula) are more compact and great for planting around vegetable gardens.

When to plant marigolds in Australia

Marigolds are warm-weather annuals, so they should be planted in spring.

You can either grow them from seeds or purchase them in pots or punnets from your local nursery or garden centre.

Growing marigolds from seeds and seedlings

Whether you want to grow your marigolds from seeds or purchased seedlings, the process is fairly simple.

How to grow marigolds from seeds

Marigold seeds | Plant care

Choose a sunny spot in the garden that has free-draining soil. Create a shallow drill and sow the seeds into this then cover lightly with soil and water.

Make sure that the soil has warmed up enough and that there is no more frost predicted before sowing your seeds. Ideally, the soil temperature should be around 24 to 28 degrees Celsius. 

You can use a soil temperature probe or even a meat thermometer to test the temperature of the soil. Insert the probe around 10 cm into the soil.

soil temperature test | Plant care

Alternatively, you can sow seeds into punnets filled with seed-raising mix in autumn and keep these either indoors or in a sheltered spot. These can be planted out once the soil has warmed up.

Marigold seeds germinate readily and you should have some flowers within around 8 weeks from seed sowing in the garden.

How to grow marigolds using seedlings

Marigold seedlings | Plant care

Whether you’ve grown your own seedlings or purchased them from a nursery, make sure that the soil is warm enough (24 to 28 degrees Celsius) before planting them in the garden.

Take your seedlings out of their punnet and separate them gently. Plant these around 20 to 30 cm apart.

For small seedlings, I either use a hand trowel or a bulb planter to create the holes.

Once your seedlings are planted, give them a good watering.

Light requirements

Marigolds will thrive when grown in full sun. Therefore, you should choose a nice sunny spot in the garden to grow them.

Marigolds | Plant care

Temperature and humidity

As these plants are summer annuals, they prefer a warm temperature to thrive and flower well. However, they’re not fond of humidity so will generally not grow well in the tropics.

Soil requirements

Marigolds need free-draining soil because they don’t like having constantly wet feet. They also don’t need overly rich soil because this may result in weak growth and not many flowers.

Water requirements

Marigolds are quite low-maintenance plants. You only need to water them when the top 5 to 10 cm of soil are dry.

watering marigold flowers | Plant care

Fertiliser

These lovely annuals are not really heavy feeders. Therefore, if you give them a dose of liquid fertiliser around once a month, that should be sufficient for good growth and flowering.

Pruning

The only pruning that marigolds really need is deadheading the spent flowers.

If you do this regularly, the plants will remain nice and bushy and you’ll get many more blooms.

Problems, pests and diseases

Marigolds are popular for planting around vegetable gardens because they are natural insect pest repellers. This is particularly useful if you’re growing broccoli, cucumbers, kale, tomatoes, eggplants or melons.

marigold flowers in vegetable garden | Plant care

However, marigolds may have their own pest problems such as aphids. But, some expert gardeners actually grow marigolds in order to attract sap suckers such as aphids away from other plants.

If you find that you do have a problem with too many aphids on your marigolds, you can either hose them off or make your own white oil and spray your plants with this.

Powdery mildew can also be a problem. That’s why many gardeners choose to grow marigolds near vegetable crops that are susceptible to this. They are a good early indicator that the disease is present.

Powdery mildew 1 | Plant care

If you notice this disease, which displays as a white, powdery substance on the leaves, spray it with a mixture of milk and water. Apparently, there’s a certain compound in milk that will stop this fungal disease in its tracks.

The only other things you’ll need to keep an eye out for are slugs and snails. These annoying pests absolutely adore feasting on young seedlings. 

You can use either snail baits or environmentally friendly snail pellets to keep these pests at bay.

The many benefits of growing marigolds in your garden

Apart from being attractive plants in their own right, marigolds have long been prized for the many benefits that they can add to your garden.

Here are just a few.

Marigolds attract beneficial insects

If you’re growing fruiting vegetables, you need to attract pollinators to your garden. The flowers that marigolds produce are particularly attractive to pollinators such as bees and butterflies.

Marigold and bee | Plant care

Predatory insects such as ladybirds, lacewings, and hoverflies also find marigold flowers attractive.

These beneficial insects are great to have in your garden because they feast on pests such as aphids and mealybugs.

Marigolds will attract slugs and snails away from your leafy green vegetables

If you have a snail and slug problem, and who doesn’t, planting marigolds around your leafy greens such as lettuces is a great idea. This is because the slugs and snails will be attracted to the marigolds instead.

Marigold and snail | Plant care

Keeping these pests away from your leafy vegetables also makes them easier to control with environmentally friendly slug pellets or other types of control such as baits or traps.

Marigolds can kill soil nematodes 

Nematodes are tiny worm-like organisms that live in the soil. While some nematodes are considered beneficial, there are others that will feed on and destroy the roots of your plants.

Marigolds roots have the ability to produce compounds that will actually kill harmful nematodes. Additionally, some marigolds can also release a chemical that can repel soil nematodes in soil where marigolds are growing. 

While there’s no conclusive scientific proof of this, it certainly can’t hurt to plant some marigolds if you think you have a nematode problem.

Marigolds can repel whiteflies

Whiteflies are a huge problem in summer where I live and it is said that marigolds can repel these annoying pests. They do this by secreting a certain compound referred to as limonene. 

It’s also believed that marigolds can repel other pests such as the white cabbage moth which is why they’re handy for growing around your brassica crops.

FAQ

Why are marigolds good for your garden?

Marigolds are a great addition to your garden because they help to attract predatory insects such as ladybirds, hoverflies, lacewings and parasitic wasps. These friendly insects feed on sap-sucking pests such as aphids, scale and mealybugs.

Are marigolds annual or perennial?

Marigolds are warm-weather annuals. This means that they need to be planted every year from either seeds or seedlings in spring. 

Photo of author

Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.

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