Gro 'n Sell

Cosmos bipinnatus

$59.00
Tray Size: 210
Variety: Xsenia

Cosmos are the easiest thing for some folks, and are deceptively difficult for others. Here are some tips:

Cosmos bloom better in poor soil. Rich soil can result in lots of foliage and little flower. They are short day plants, that are triggered to flower as days get shorter in the late summer. Pinch plants a couple of times when young to develop long side shoots. Cutting long stems will help them to produce long stems. Deadhead regularly to keep plants productive.

Photos are provided as a guide not a guarantee of exact colors and shapes.

**We do not guarantee any specific shades will appear in Mix products, as the Mix is created by the seed breeder.  It is possible that Mix will be all one color, or significantly different from pictured colors. If you need specific shades, please order straight colors as opposed to Mix trays.**

Order 7 or more weeks in advance of desired ship date. 

About Tray Sizes

210 and 125 cell trays are full-sized trays, and three of these will fit in a shipping box.

50 cell trays are half-sized trays (unless otherwise noted) and two of these are the equivelent of one full sized tray. Six of these will fit in a shipping box.

18 and 32 cell trays are full sized trays specifically for our vernalized perennials. These have their own set of shipping rules (find details HERE) and cannot be combined with items grown in 210, 125, or 50 cell trays.

Growing Guides

Click here to access all of our comprehensive growing guides.



Common Name Cosmos, garden cosmos, Mexican asters 
Genus  Cosmos 
Species C. bipinnatus
Family Asteraceae
Life Cycle  Tender Annual 
Format Plugs
Plug Care Harden off and plant or bump up soon after receiving.  Cosmos are very quick growing and will soon become rootbound if left in the original plug tray.   
Netting / Staking One or two layers of netting is beneficial in areas with  high wind.  
Temperature Range Plants can not tolerate freezing at any point in the growth cycle. They can handle the heat of summertime and are a crop suitable for most zones. 
Spacing  9-12" 
Soil Preference Loose, well draining soil with low fertility. Too much nutrient content will cause heavy foliar growth and few     flowers. 
Day Length Short day plants - flowering is triggered as days get  shorter, typically towards the end of summer. If stressed  rootbound or drought conditions) they will flower  prematurely. If growing in a greenhouse through the winter, additional lighting will be required to mimic long days for the vegetative state. 
Pinching Pinch once when the plants are about 6" high, down to a few sets of leaves to encourage side branching. If the  plants try to flower prematurely, continue to pinch off  buds and flowers until you start seeing longer stems. 
When to Plant Plant in the spring after all danger of frost has passed.  Succession sow 2 or 3 times (about 4 weeks apart) for continuous blooms through to frost. 
Harvesting Expect flowers approximately 45-60 days after planting plugs (dependent on weather and temperature).  Harvest when flowers are just starting to open for the longest vase life. Mature side buds will also open in the vase. Cut deeply into the plant for long stems and to promote additional side branching. If flowers are left to open fully they will get pollinated and vase life will suffer. 
Post Harvest Care Place cut stems immediately into cool water. Floral  preservative will extend vase life - expect stems to last    just shy of one week. Can be stored in the cooler for a  short period of time. 
Diseases / Insects During long stretches of heat and humidity powdery  mildew and bacterial wilt may be seen. Common insect  pests include aphids, thrips and Japanese beetles.  
Bailey's Notes

Do not allow plants to set seed - keep up with harvesting and deadheading or the plant will start to shut down. 

Some growers will use stems of cosmos foliage as a filler in bouquets - they have reported a good vase life although we don't have personal experience to support  this claim. 
Resources  NA