Paddy,
The semp flower opens its anthers first. The stigma is generally not too receptive at that point. The tips of the stigmas should feel slightly sticky and they spread out sort of like a rack of lamb. To do controlled pollinations you need to cover the stalk. I use simple small paper bags to cover the bloomstalks to prevent insects from contaminating the crosses but we have essentially no rain in the summer here so the bags don't get wet. In MA I used muslin bags. Old panty hose works too.
OK so you watch the flowers now. On the ones you want to set seed you need to go in and remove the anthers before the flower opens. They are tiny globes at the tips of the anthers at this point. I use Dumont #5 tweezers as they have a very fine tip so that you can pull off these anthers without ruining the flower. Leave these flowers alone until the flower adjoining it develops sticky anthers. Now you are ready to pollinate that flower. In flowers you want to use for pollen, you leave these anthers on the flower. When they dehisce you will see a quantity of yellow pollen on them. You can either use the whole flower and rub it over the stigmas of the pod parent or pluck bunches of the yellow pollen with tweezers or a fine artist brush and make sure you have pot pollen on those stigmas. Keep the bloomstalk covered until all the flowers have been pollinated. I mark the name of the cross on the bag and also in a notebook as you can forget what crosses you have made otherwise. By marking the bag, I have a double indicator of what I'm doing.
Hope that helps!
Even in heuffs only the flowering stem dies. The rest will be fine.
Kevin
