Gardening tasks for August
any of the above - or preferably all of the above
Rudbeckia laciniata 'Herbstsonne'
There is no rest for the wicked. Having taken a relaxing couple of weeks thinking my garden might well do the same I'm back out there, nose to the grindstone and shoulder to the wheel.
As always at this time of year there seems to be a re-emergence of weeds in lawns. Its a little early still to apply autumn lawn weed and feed treatments - in Ireland with our moist and mild climate the grass season can be a month longer than many textbooks would suggest, so I would hold off until mid-September for that.
In the meantime you can spot treat weeds with a selective lawn weed killer, one that kill broadleaved plants but not grasses. Buy ready-mixed solutions or, if mixing yourself, be sure to follow the mixing ratios carefully as while the weed killer is selective to broad leaves a strong mix will damage your grass as well. I speak from experience.
If you have a moss problem you can start treating that too. Sulphate of iron will do the trick but blacken the moss that will need raking out afterwards.
A newish product called Mo Bactor contains a bacteria that eats away the moss leaving no blackened areas and requiring no raking. It does contain a slow-release fertiliser but I would not see any harm applying that even at this time of year. Of course it is expensive compared to sulphate of iron.
Lavendula angustifolia needs clipping back now, leave the taller Lavendula x intermedia varieties for another couple of weeks. Don't cut into the old wood with no foliage as it won't regrow but do cut back hard to live growth. Wisterias are also due a summer prune. Remove all the new lateral shoots and those that are long and wispy back to about twenty centimetres of the old growth. This only needs to be done on established plants that are of a size you want. On young plants tie in new growth to supports to create your desired framework and remove any excess.
A second hedge clipping can be done now. This will keep your hedge really tight and compact in growth and looking good through the rest of the year. Clipping now will also allow any new growth to harden off before winter. Pruning rambling roses can also be carried out now in a similar way to the wisteria but try to remove a quarter of the old growth and replace with strong new shoots. Continue to dead head herbaceous plants like Phygelius, Penstemon and Dahlias to encourage flowering well into autumn. I leave the seed heads of Agapanthus, Libertia, Astilbe and Dierama as they are attractive in their own right, I do give a couple of liquid feeds just to strengthen the plants energy levels.
Seed collecting is another job on the list. Beans and peas in the vegetable garden can be dried and used next year. Herbaceous plants like foxgloves, aquilegia and honesty will self seed but if you want to control their spread remove the seed heads early then dry them out and store for controlled sowing later.
You can still take semi hardwood cuttings of Hydrs fangea, Fuchsia and most woody plants but do this before the end of the month. Strong strawberry runners can be removed and discarded or used to replenish or replace your old existing stock.
Be vigilant with your regular watering of plants in pots, even if it rains it probably won't be sufficiant to what is required. Liquid feed annual bedding on at least a weekly basis, often at this time of year these plants can begin to tire but if looked after they will continue to produce flowers for at least another month.
If you stll have time on your hands you can turn over your compost heap with a garden fork to encourage faster decomposition.
When all these little jobs are done sit down with a cup of tea and plan your spring flowering bulb planting scheme for September planting.