When sowing sweet peas put the seeds between two layers of kitchen towel on an old dinner plate, dampen the towel, drain off excess water and sow those that start to swell or sprout which takes around 48 hours. Leave any others; you may want to try chipping the seeds with the end of a sharp knife or abrading them with sandpaper but not deeply enough to damage the living endosperm inside, then pop them back to see if they germinate, those that don’t can be composted.
Sow the germinating seeds individually into ‘Root Trainers’ or 9cm (3in) pots of seed compost or five to seven seeds to a 13cm (5in) pot, spaced 2-3cm (¾-1¼in) apart, then cover the seeds with 1cm (½in) of compost. Water in gently, then put them in a propagator at about 15°C (59°F). Remove the covering once they appear and overwinter young plants in a cold frame or unheated greenhouse. Transplanting seedlings into 9cm (3in) pots once they have reached about 3.5 cm (1½in) tall. Sweet peas make lovely presents for gardening friends; I gave ‘Cathy’ to my sister of that name, ‘Just Christine’ to my friend Christine and am sowing ‘Cedric Morris’ because I like his art and his Irises even more. We have relatives from New Zealand visiting next year, so the aim is to have ‘Lisa Marie’ flowering when they arrive, in memory of their late daughter.
It has been warm so far this autumn so tender plants will stay outdoors as long as possible, while constantly checking the weather forecast and bringing them under cover before the first frosts, Cutting back the main stems of pelargoniums to within a few inches of the base and keeping them slightly moist over winter, (more are killed by overwatering than under watering) maintaining a temperature of around 10°C (50°F) over winter. It’s also time to lift cannas and dahlias in cooler climates, bring in pots of Heliotrope, Fuchsias and marguerites. Fuchsias, cacti and succulents should be treated with Vine weevil biological control nematodes before bringing them into the greenhouse.
Clear autumn leaves from greenhouse gutters as they start to fall and add them to the compost heap or leaf pile, depending on the volume you collect. Prevent downpipes from clogging by putting a pan scourer in the hole at the top, then clearing the debris from the guttering as it backs up. Collect rainwater in a water butt and when it is full, water at the base of fences under the eaves of your house where it is dry – anywhere in the garden where there is a rain shadow, rather than letting it overflow and drain away. https://hartley-botanic.com/product/water-butts/
Water plants sparingly and avoid wetting the leaves to prevent fungal problems and open the vents on warmer days. Watering in the morning means that accidental splashes will have dried out by nighttime.
Make the removal of dead diseased or dying leaves from greenhouse plants a daily task, as seasonal humidity causes fungal problem to spread. Happy gardening. Matt