How to Grow Pot Marigolds: A Practical Guide from Seed to Flowers

Pot marigolds, or Calendula, are one of those flowers I'd happily recommend to anyone who's fairly new to growing from seed. The seeds are large enough to handle easily, they can be sown straight outside and the plants get going without needing lots of attention.

Despite the name, pot marigolds aren't the same as the French and African marigolds we grow as summer bedding. Calendula are hardy annuals and are much happier dealing with cooler conditions.

They produce cheerful yellow and orange flowers through summer, and varieties such as Pacific Beauty give you a lovely mixture of warm colours.

They're useful plants too. Bees and other pollinating insects visit the flowers, they're good for cutting, and the petals are edible. 

I like to sow them directly where they're going to flower. Give them a sunny position, don't overfeed them and remove faded flowers regularly if you want to keep the display going.

When to Sow

Pot marigolds can be sown in spring or autumn.

For spring sowing, March to May is ideal. They're hardy enough that there's no need to wait for the warm conditions you'd need for French marigolds or petunias.

I usually sow directly outside once the ground is workable.

You can also sow in August or September for earlier flowers the following year. Young plants establish before winter and start growing again when conditions improve in spring.

If you're new to growing flowers, I'd probably start with a spring sowing simply because it's so straightforward.

There's also nothing wrong with making another small sowing a few weeks after the first. This can help spread the flowering period rather than having every plant reach the same stage together.

How to Sow

Calendula seeds are wonderfully easy to handle. They're large, curved and rather odd-looking compared with many flower seeds.

For direct sowing, prepare the soil by removing weeds and breaking up any large lumps.

Make shallow drills around 1–2cm deep and sow the seeds reasonably thinly.

Cover with soil, gently firm the surface and water if conditions are dry.

You don't need to create perfect rows. If you're growing them in an informal border, sow small groups where you'd like splashes of colour.

Keep the soil reasonably moist while the seeds germinate.

You can also sow into pots or modules if you prefer. Sow individually or a couple of seeds to a small pot, cover lightly with compost and keep them watered. I often plant a few trays of seeds early in the season.

Once the seedlings appear, give them plenty of light.

Thinning and Growing On

If you've direct-sown your pot marigolds, thin the seedlings once they're large enough to handle if they've come up too thickly.

Aim for roughly 20–30cm between plants.

Don't worry about getting the ruler out. You're simply giving each plant enough room to branch and produce plenty of flowers.

If you've started plants in pots, plant them outside once they're established. Calendula are hardy, but plants raised under cover still benefit from being gradually accustomed to outdoor conditions.

Water after planting and keep them watered while their roots settle.

Once established, there's very little complicated growing-on work involved.

Keep weeds under control while plants are small and let them get on with growing.

This is exactly why I like them for beginners. You don't need to spend weeks potting them on, pinching them out or worrying about complicated growing techniques.

Growing Pot Marigolds in Containers

The name rather suggests it, but pot marigolds grow very well in containers.

Use a pot with drainage holes and fill it with good-quality multipurpose compost.

You can sow directly into the final container and thin the seedlings once they appear.

A larger pot containing several plants usually makes a better display than trying to grow one plant in a tiny container.

Place it somewhere sunny.

Container-grown Calendula need more regular watering than plants in the ground because compost dries out faster, particularly during warm weather.

They work particularly well if you're just starting with a few pots on a patio. The seeds are easy to sow, the plants don't need elaborate care and you get plenty of colour for relatively little effort.

Watering and Feeding

Keep young plants watered while they're establishing.

Once they're growing well in the ground, pot marigolds are fairly tolerant and usually only need extra water during prolonged dry spells.

Plants in containers need checking more regularly.

Water thoroughly when needed rather than continually giving the surface a small splash.

Calendula don't need particularly rich soil or lots of fertiliser.

In ordinary garden soil, I generally wouldn't feed them at all.

Container plants that have been flowering for a long time may appreciate an occasional general-purpose liquid feed, but don't overdo it.

Too much feeding can encourage plenty of leafy growth when what you really want is flowers.

Sunshine, reasonable soil and regular deadheading will generally do more for the display than endless feeding.

Flowering and Deadheading

Pot marigolds usually begin flowering from late spring or early summer and can continue well into autumn.

Regular deadheading makes a real difference.

Once flowers begin fading, remove them before the plant puts all its energy into producing seed. This encourages it to keep making new flower buds.

You don't need to inspect every plant daily. Going over them every so often and removing the obvious faded flowers is plenty.

If you'd like the plants to self-seed or want to collect seed yourself, stop deadheading some flowers later in the season.

I tend to do a bit of both. Keep some plants flowering and allow a few seed heads to develop.

Growing for Cut Flowers

Calendula make useful cut flowers and varieties such as Pacific Beauty give you a lovely mixture of yellows and oranges for the vase.

Pick flowers when they're fresh and newly opened.

Cutting flowers regularly has much the same effect as deadheading — it encourages the plants to continue producing more.

If you're growing specifically for cutting, sow several plants together so you can take a few stems without removing the whole garden display.

Put cut stems into water fairly quickly after picking.

They're not the grandest cut flower in the garden, but that's part of their charm. A handful of Calendula mixed with other home-grown flowers makes a lovely informal bunch.

Flowers, Bees and Edible Petals

The open flowers are visited by bees, hoverflies and other pollinating insects, so pot marigolds are useful plants to have amongst vegetables and other flowers.

The petals are edible too and can be used to add colour to salads and other dishes.

Only eat flowers that you know have been grown for edible use and haven't been treated with pesticides or other products unsuitable for edible crops.

Don't feel you need to pick everything, though.

I like leaving plenty of flowers for insects and taking the occasional one for the kitchen or vase.

That's one of the nice things about Calendula — one very easy plant can provide colour, cut flowers, edible petals and something useful for visiting insects.

Saving Seed and Self-Seeding

If you stop deadheading, you'll soon notice the unusual curved seeds developing where the flowers used to be.

Leave them on the plant until they're mature and dry.

Collect the seeds on a dry day and store them somewhere cool and dry until you're ready to sow again.

Pot marigolds can also self-seed quite happily.

If you leave some mature seed heads in the garden, you may find seedlings appearing the following year without having deliberately sown them.

They won't necessarily appear exactly where you would have chosen, of course. Plants seem to regard our carefully planned borders as more of a suggestion than an instruction.

Move or remove unwanted seedlings while they're young and leave the useful ones where they are.

Common Problems

Slugs and Snails

Young Calendula seedlings can be damaged by slugs and snails, particularly during damp spring weather.

Keep an eye on newly emerged plants until they're established. Larger plants generally cope much better with a little damage.

Aphids

Aphids can sometimes gather around tender shoots and flower buds.

Small colonies can often be washed away or left for beneficial insects such as ladybirds and hoverfly larvae to deal with.

Powdery Mildew

A white powdery coating can occasionally appear on the leaves, particularly later in the season or when plants are stressed.

Give plants enough room for reasonable airflow and keep them watered during prolonged dry weather.

Lots of Leaves but Few Flowers

Too much shade or very rich soil can encourage leafy growth at the expense of flowers.

Give Calendula plenty of sunshine and don't feed them unnecessarily.

Plants Becoming Untidy

After flowering for a long time, plants can begin to look rather tired.

Cut back straggly growth, remove old flowers and give plants some water. They can often produce another flush of growth and flowers.

Flowering Stops

If you've allowed lots of flowers to develop mature seed, the plant may naturally slow down.

Deadhead regularly while you want flowers, then leave some seed heads towards the end of the season if you'd like to collect seed or encourage self-seeding.

Pot marigolds are difficult to beat when you want an easy flower that gives plenty back. Sow them straight outside, keep young plants watered and deadhead once flowering begins. Pacific Beauty is particularly good for a beginner because you get that lovely mixture of warm yellows and oranges without needing to do very much to earn them.