Posted: 17/09/2015 at 10:54
As a general remark, I would add that when seed companies state on the back of their packets to sow in autumn or specify different months, it should be understood that the back of a seed packet doesn't offer them much scope.
By way of explanation I would say that autumn sowing of sweet pea seed is a balancing act and being so, no definitive time can be given for sowing.
The best case scenario is to sow the seed and as soon as it has germinated hope for the onset of cold weather to keep them from putting on further growth.....the general idea being that in October (or whenever) there is still sufficient natural warmth to germinate the seed before the onset of winter......in other words the optimum time.
With the above in mind (and with a little practice) it's advisable to sow according to the existing weather, not a particular week/month.