Everything you need to know about Cosmos Seeds

Cosmos seeds Questions and Answers:


When should you plant cosmos seeds?
In Europe, when to plant cosmos seeds depends on your location and climate. In a Mediterranean climate, the best time to plant them is either in September to October after the hottest weather has passed or in February/March. For continental climates, plant your cosmos seeds in May or after the frost risk has passed.

Are cosmos difficult to grow from seed?
Cosmos are considered one of the easiest flowers to grow from seed. They are easy to germinate, fast growing, tolerant of various soil conditions and don't require frequent watering. Cosmos are ideal for inexperienced gardeners and also give a massive reward with abundant blooms throughout the summer.

Can you save seeds from cosmos?
Yes, you can absolutely save cosmos seeds. Wait until your cosmos flowers have faded and dried out and are slightly brown and papery. Separate the seeds from the other parts of the flower head. Spread them out on a paper towel and allow them to dry for 7-10 days.

Do cosmos come back every year?
Most cosmos varieties are annuals, meaning that they won't come back the following year. The exception is Chocolate cosmos, which is classified as a 'tender perennial' and may return in warmer climates.

How long does it take cosmos to grow from seeds?
Cosmos seeds take up to around 7 days to germinate and approximately 50-60 days until the plants start to bloom. Cosmos takes up to 90 days to reach their maximum height.

Do cosmos need full sun?
Cosmos needs at least 6 hours of direct sunlight to thrive. In warmer climates, they can tolerate slightly less light but might produce fewer flowers and weaker stems.

Can cosmos grow in pots?
Yes, cosmos grow perfectly well in pots. Choose a container of about 30cm in diameter that has drainage holes. Place the pot in a sunny location and water regularly.

How do you make cosmos bushy?
To encourage branching (this leads to a bushier plant), the key is to pinch back the seedlings. When the seedlings have 3-4 pairs of leaves, pinch off the growing tip. You can repeat the pinching when the plants reach 20-30cm in height. Continue to prune back any long or leggy stems.

Will cosmos reseed themselves?
Yes, if left alone, cosmos plants will re-seed themselves. If conditions are  favorable, they will germinate the following spring and produce plants that will resemble the parent plant (occasionally there is some variation in color).

Where do cosmos grow best?
Cosmos grow best in areas with full sun, well-draining soil, and moderate temperatures. They thrive in warm and temperate regions and can tolerate dry conditions once established. Cosmos can grow equally well in both garden beds and containers.

How deep to plant Cosmo seeds?
Plant cosmos seeds about 0.5cm deep. Gently press the seeds into the soil and cover them lightly with a thin layer of loose soil or compost. Keep soil consistently moist until the seeds germinate and seedlings emerge.

Why are my cosmos not flowering?
Cosmos usually bloom very easily. If your cosmos isn't flowering, it could be due to lack of sunlight (they need 6 hrs a day), or very poor quality soil. Also check when you planted your cosmos seeds as they need 50-60 days to begin blooming but this could be delayed with cooler temperatures.

Do you cover cosmos seeds with soil?
Yes. While cosmos seeds don't need to be planted deeply (0.5cm is deep enough), they should be covered with a thin layer of loose soil to keep them in place and provide moisture and protection.

Do cosmos seeds need darkness to germinate?
No cosmos seeds don't need darkness to germinate. Quite the opposite, they germinate best in a well-lit environment. They actually need the light to trigger the germination process.

How long do cosmos live?
Cosmos are annuals and complete their growing process within one season. However, their blooming season can be quite long in warm climates, with plants flowering continuously throughout the summer.

Do slugs eat cosmos?
Yes, slugs are known to feed on cosmos plants, particularly young seedlings and tender foliage. They chew holes in the leaves and stems, which can hinder growth and flowering. Try to use slug repellents or use copper barriers or other organic slug control methods.

How long will cosmos bloom?
Cosmos flowers typically bloom continuously throughout the summer
and into the fall, Pruning and deadheading (removing spent flowers) will extend their blooming period and cosmos can continue to flower until the first frost arrives. Depending on the variety and growing conditions, cosmos can flower for about 2 to 4 months or even longer.