Diarmuid Gavin: The garden's gift
Harvest seeds and cuttings from your own plot this month to fill your beds - for free - next spring
August is the time to begin to think about next year's garden. One of the ways of doing this is to start considering the propagation process - examining what you have, seeing what's done well this year and beginning the sequence all over again by ensuring that you have more of the same next season.
All species like to survive, and to do this they procreate. With plants, that's often by setting seeds. In late summer after flowering, many plants produce the seeds that will help preserve their genetic line. Now is the time of year when many pods are bursting with seed that can be collected and saved for sowing in spring.
It's also a very good time to try another method of propagation, taking cuttings.
Both are low-cost ways of increasing your garden stock, and even if you only do a couple of pots, it can be very satisfying to watch your favourite plants grow from seed or cutting. Get children or grandchildren involved, and spark their interest in gardening by cutting open unusual seed pods and explaining the magic contained in these tiny capsules.
Collect seed heads on a dry day and pop into brown envelopes or paper bags, labelling as you go along. Then on your kitchen table, open the seed heads and shake out the contents onto some kitchen towel - this will blot up any excess damp. Remove any chaff, as this can cause rot. Don't store seed in plastic bags as this can encourage moisture retention and fungus. If you don't have brown paper, greaseproof paper will also work.
Seeds for spring sowing can be stored somewhere cool and dry - not in your airing cupboard which is too warm. Some seeds, such as astrantia, foxglove, angelica, aquilegia (above), meconopsis, primula, orlaya and delphinium, can be planted straight away.
With very fine seeds, use seed compost with a layer of grit on top and surface-sow them. You can also hedge your bets by sowing some now and some in spring - or if you're waiting to decide, pop them in an airtight container in the fridge where they will keep well.
You can take cuttings from many tender herbaceous perennials now such as salvias, osteospermum, fuchsias (above), pelargoniums and argyranthemums. You might also do this as a sort of insurance policy with plants that you chance leaving in the ground over winter such as penstemon. At least if there's a hard winter, you know you have its young offspring safely indoors.
Generally, the rule for cuttings is to do it early in the morning and immediately pop into a plastic bag to retain moisture until you pot them up. However, with pelargoniums you can let the cutting dry out a bit for a couple of days so the end of it forms a bit of a callus and this will help your cutting survive. Select a piece of new growth that isn't flowering and cut just above a leaf.
The key to success in cuttings is the compost you use: it needs to be very free-draining so they don't rot. I use sand or horticultural grit in seed compost at a 50:50 ratio. Remove leaves from the bottom third of the cutting and, using a dibber, pop into the pot. You can use hormone-rooting powder; it's not necessary but can give a real boost to the strike rate. If you are using it, don't overdo it as this can be counter-productive - just a very light dusting is sufficient.
When putting a few cuttings in one pot, keep them to the sides of the pot (where it's warmer) rather than sticking one in the middle. Bottom heat from a propagator is a good way of encouraging roots to form.
If you're just doing a few cuttings, it's a good idea to keep them indoors on a kitchen windowsill (so long as it's not in direct sunlight) or somewhere you will pass regularly to keep an eye on them. There's a fine balance between over-watering and letting them dry out.
You can cover the pot or tray with some cling film to conserve moisture, but every few days lift the cling film and shake the drops out.
At this time of year with long day light hours, usually within four-to-eight weeks you'll be able to see roots developing - just turn the pot upside down and inspect. Once you can see a cluster of roots, you have a plant that's ready to be potted on.
So take a walk in the garden, see what you like and get harvesting!