Many Agapanthus will be still in flower this month so keep on top of your
liquid feeding with a good high potash feed such as “Geranium Elixir”
which is used here on the nursery. Cut off any flowering stems that have
“gone over” to stop them trying to form seeds and thus waste their
energy. The Agapanthus that have now come to the end of their flowering time
still need feeding this month. What you do with your Agapanthus this year
affects their flowering availability next year, so keep up their food intake to
prep them for next summer.
Continue to dead head & liquid feed your Pelargoniums to keep them
flowering for you that goes for your Penstemons too, which will often flower
well into October.
Most Heucheras will have finished flowering by now so go through them and
cut back the flowering stems to leave a lovely bushy mound of foliage for your
borders or pots, it really does freshen up the look of the plants. I love the
fact that Heucheras keep their foliage all year round, as they create much
needed structure in the borders throughout the winter months.