I always suggest to gardeners to have duplicates of all the pots you have, this way when you have one set all planted up and looking great at the front of the house or in situ, you can have another set with the follow on plants starting to fill out. So at this time of year you could be planting up your Autumn/Winter flowering pots with Cyclamen, Ornamental cabbages, Solanums, Pansys, Asters and the likes so that when your summer ones started to turn you can lift them away and swap for the fresh containers for the next season…You’ll find most of the great gardens and displays are worked in this way.
However if you have only the one set of pots then now is the time to be emptying them out, filling with fresh compost and replanting…I know there still looking good, but let’s be honest they’ve went past their best and it’s important to replant now so that your new plants have a good 6 weeks of growth to get established before the weather turns cold and growth slows…or even stops.
A question I get asked routinely is “Do I have to replace the compost in the pot”, the simple answer is Yes. After a growing season the compost you’ve used is spent, the goodness has been used and its been ‘soured’ by the effects of water and fertiliser application. So it’s best to empty it all out, put it in the compost heap or into the garden and then refill the pot with fresh compost. Something I started to do a few years ago was empty my compost into a wheelbarrow and then fill it up with water, this helped to kill off any vine weevil larvae which may be lurking in the potting mix!
So part of this time of year is being brutal with your plants, accept that in 6 weeks its getting cold so you want…you need to get your new plants in an established now. This is the exact case in the polytunnel too. Yes your tomatoes are still growing, yes they still have red and green fruit, but see those green fruit the ripening process is now getting slower and slower so now is the time to take action. To help the plants to ripen fruit you need to increase the amount of ethylene gas so start putting buckets of fresh veg and fruit peelings beside the plants, buckets of fresh dung help too. Also reduce watering and feeding to encouraging ripening and then in a fortnight lift the plants up and hang them (fruit and all) upside down on a hook in the shed to get the last of the toms to ripen. Alternatively what I do is just pick all the fruit now and put it in a paper bag with a banana, this way I can dig out the plant now, condition the soil and start to get my Winter salads sown now, some early spring cabbage and some sprouting broccoli for the spring.
So grab the bull by the horn, accept summer is over and get changing!!