Cosmos, colors and light: planting, care and blooming

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Flowers in white, pink or red, or in hues running from yellow to orange depending on the species: cosmos is an easy annual that is spectacular from spring to autumn, its generous blooming constantly renewing itself. Avoid compact, heavy soils that hold water, deadhead as you pass, and the flowers seem perpetually fresh.

A very easy plant to succeed in growing, the blooming is abundant and its decorative effect is guaranteed.

Sowing Cosmos

In spring, right from the middle of the month of mid-spring, choose a full sun location to sow your cosmos.

If you live in areas that are farther up North, best sow starting from late spring.

In summer, it is always possible to plant your cosmos plants purchased in a nursery pot, but the most common technique is to sow them directly from seed.

• After having sown the seeds, water regularly to ensure that the soil remains damp.
• Once seedlings have sprouted well, you may thin them to give breathing space to your young plants. This means removing those sprouts which are too weak and too crowded together.

Just like the aster, ordinary soil mixed with a bit of soil mix is perfect.

• Avoid compact and heavy soils that would retain water instead of releasing it to the plant.
• To nicely cover a surface, plant around 8 or 9 flowers to a square yard (1 m²).

Care and pruning of cosmos

Easy to grow, cosmos only asks for very little care.

For long stemmed varieties, feel free to stake them to avoid having them double over in case of wind.

Deadheading will help renew blooms. It also makes the flowers seem perpetually fresh!

• Note: if you want seeds, let a few flowers mature and dry out.

• Avoid feeding cosmos with nitrogen-rich fertiliser, as generous soil pushes lush leafy growth and floppy stems at the expense of the flowers the plant is grown for.
• Pinch out the growing tip of young cosmos plants once they have a few pairs of leaves to encourage side branching, giving bushier plants and far more flower stems.
• Water cosmos only during prolonged dry spells once the plants are established, since they cope well with drought and sulk in soil kept constantly wet.
• Insert stakes for tall varieties while the plants are still small and tie the stems loosely with soft twine, since staking after a plant has toppled risks damaging roots and stems.

Popular cosmos varieties at a glance

The named varieties below are the ones you are most likely to find on a seed rack or in a garden centre. Match the height and colour to the spot you have in mind, then simply sow and deadhead.

All there is to know about cosmos

A plant for flower beds, edges or rocky land, cosmos is spectacular from spring to fall thanks to its generous blooming which constantly renews itself.

An easy annual, there are many different varieties and species which makes for just as many shapes and colors.

As for pests and diseases, Cosmos is rather something of a paradox:

• It attracts aphids away from other plants, thus protecting them. This makes it easier to use as a decoy to eradicate early aphid colonies.
• Conversely, it repels certain butterfly pests, like large white, from laying eggs in the area. But it still shares its nectar to them willingly.

Common varieties of cosmos

These can be divided into three large groups, for the most common flowers

• Cosmos bipinnatus – the most common one, with white, pink or red flowers.
• Cosmos sulphureus – the hues from these vary from yellow to orange.
• and finally, Cosmos caudatus – a more wispy variety native to South America

Not a very hardy plant, cosmos cannot withstand temperatures below freezing. This goes for all varieties. It explains why it must be grown as an annual in cold climates.

• In warm climates, cosmos will grow to a bushy 4 feet tall (1.30 m), and has a lifespan of about 8 months.

Cosmos, beautiful edible flowers

From the three groups mentioned above, only two are traditionally regarded as edible: Cosmos sulphureus and Cosmos caudatus.

• Pick young leaves and flowers and add them to chop suey.
• Sprinkle a few petals to decorate a colorful salad bowl!

The most common Cosmos family, Cosmos bipinnatus, is not considered edible. Since it isn’t toxic in any manner though, it’s still very safe to grow around children and pets.