Cosmos Seedlings

Garden Cosmos Seedlings

Cosmos bipinnatus varieties, commonly known as Mexican Asters in America, are increasingly popular annuals and for good reason. They flower their socks off from May until Autumn. This makes them ideal for containers as well as flower borders or cutting beds in larger gardens. When cut, cosmos last for up to a week indoors and the more you cut them the more they flower. They are easy to grow, reaching 60-90 cms tall and are pretty much disease and pest free.

Cosmos in Summary

• Uses: Annual flowering bedding
• Good Points: Free flowering from May to September, plain and variegated pastel colours, wonderful cutting flower
• Position: Likes a sunny spot with decent soil that retains a bit of moisture
• Growth: Up to 90 cms

Order Cosmos Seedlings

Choosing, Planting and Growing Cosmos

Choosing Cosmos

The best Cosmos are sown in early spring, under cover, as "plugs" so that they have a well-developed root system by the time they are despatched from early May onwards at which point they are ready to be planted out into their final flowering positions. We grow our plants from the best quality seed we can find as there is no doubt that seed quality significantly affects plant quality. With an eye on the environment, they are germinated in peat-free compost with a slow release fertiliser to keep those roots going until they are planted out. And they are germinated in ideal conditions; frost-free tunnels with steady watering to ensure good growth. We just try to produce the best...

Planting Cosmos

Planting holes should be deep enough to accommodate the plug and to allow you to cover it over with about 1-2cms of soil. Our seedlings are well enough developed for you to be able to plant them straight into their final positions, with no need to thin them later and therefore no wastage. When fully grown, Cosmos like to grow with about 25-35 cms (8-14") between plants so use that spacing when you are setting them out. If you are staking them individually, use a bamboo cane about 5 cm from the plant. You can also support them by putting a few canes around the planting area and stretching some pea or bean netting between them about 30 cms above soil level. Your Cosmos will grow through and hide the netting very quickly, and it saves a lot of fiddly tying with twine.

Growing Cosmos

Ideally, Cosmos like a well-worked bed with a bit of organic matter added, but they flower best on soil that is not too rich. However, their principal requirements are sun and water. Cosmos grow very quickly indeed, so they need moisture in dry spells. To help them bush out and so produce as many flowers as possible the tips should be pinched out when they are about 20-30 cms tall. 

As the flowers develop cut them for indoors or if you want to leave them on the plant, deadhead when they are finished to extend the flowering period. To maximise flower size and colour, feed with a high potash and phosphate fertiliser during the growing season. Home-made comfrey liquid or Tomorite both work well.

Buying Cosmos

Our Cosmos are grown as maxi-plugs which give them a bigger rootball than is generally available elsewhere. They are sold in packs of five with quantity discounts as you buy more of any one variety. Delivery is when the plants are ready and the weather permits but is generally from the beginning of May onwards. We will, of course, email you when your order is posted to let you know your Cosmos are on their way.

Please note that annual plants are not covered by our year guarantee, because they are not supposed to last that long!