By Alextb
London,
England 
I ahve been told taht Cosmos love being negelcted, and that they should be palced in poor soil with no feed for best results. As it likes neglect, how much should watering be restricted. Should it be little and often, or a little when the surface is dry or a lot and not very often?
Also, is the above about soil and feed correct?
Thanks in advance
12 May, 2011
Answers
O.K, thank you
12 May, 2011
In containers, though, they will need more feed and water.
14 May, 2011
I thought feed was an absolute no-no. I thought the only care would be occasional watering, and deadheading?
14 May, 2011
Well, if you have an unusually rich compost that has enough slow release nutrients for the whole season, then feeding might not be necessary. Most often, though, they will start to turn yellowish, and stop growing and blooming, after 6-8 weeks without some kind of feed.
14 May, 2011
Oh, O.K then. Thanks Tugbrethil
15 May, 2011
Hi, you have been well informed.
Cosmos grow to about 1-2 metres in scrub land in South Africa - you often see them by the side of the road. They thrive on poor, dry soil with little water, so yes neglect them but do deadhead unless you want to collect seeds. They self-seed reasonably well in the UK. They do not tend get to 2 metres in UK but could.
If you grew by seed they would not be flowering now, normally in June, so am not sure how your pot bought ones will do - certainly let them seed and you will get some next year and get better value for money.
12 May, 2011