August Gardening Jobsi
August Garden Jobs: How to Maintain Your Garden in Late Summer
Could there be a lovelier month in the garden? (Yes, we know… we say this every month!). But seriously, August! The borders are full to bursting, there’s colour everywhere you look, and the sun can be relied on to shine at least some of the time.
This is the moment for enjoying the fruits of your labour. But don’t put your feet up for too long…! There are still plenty of jobs to be getting on with, for August is the month of hedge trimming, watering, a little pruning, and propagation. Well, you wouldn’t want to take it too easy, would you?!
- Trees, hedges, and shrubs
- Garden maintenance
- Pests and diseases?
Top garden jobs to do in August
Trees, hedges, and shrubs
August is one of the hottest months of the year and when plants can dry out the most. Relatively easy to remember are herbaceous plants and pots, which we cast our admiring eye over. Much easier to miss is the structural, woody planting, often escaping our attention until it becomes desperately brown and crispy.
Follow our simple tips to ensure your trees, hedges, and shrubs remain well-hydrated and continue to thrive.
- Water all newly planted woody plants regularly throughout their first year in the ground. We recommend a good, long soaking at least once a fortnight during the warmer, drier months.
- Even mature woody plants can show signs of water stress in periods of extreme heat and drought. Particularly vulnerable are those with larger leaves or restricted root growth (such as next to a wall). Early signs to look out for are dull and lacklustre foliage, or leaf tips beginning to brown. For more advice on how to care for plants during hot weather, take a look at our guide to gardening during a heatwave.
Irrigate in the morning or evening to minimise water lost through evaporation.
A slow and steady trickle will penetrate the soil more efficiently than a strong blast. Either leave a hose on little more than a drip for several hours, or invest in a leaky hose irrigation system (particularly good for hedges).
Read our How to Water Plants guide for more tips.
For some plants, the crucial moment for pruning is not winter, but summer. This might be to ensure the next year’s flowers, maintain a neat shape, or both.
For best results prune twice a year - once in August, to tidy and allow sunlight in to ripen next year’s flowering wood, and again in winter to encourage the formation of lots of stubby, flowering spurs.
Though this may sound complex it is really very simple! All you need to do now is take back all strong, new growth to five buds, as well as remove this year’s tatty, spent flower stalks.
August is an ideal time to prune several deciduous, climbing, summer-flowering shrubs:
The long, trailing stems of deciduous honeysuckle may be shortened to three or four leaves. Take older stems out down to the ground to promote new growth and avoid a ‘bare bottom’. Jasmine
The flowered stems of summer-flowering jasmine can now be cut back to a strong sideshoot lower down.Pyracantha
Once the main framework of a trained pyracantha is established, shorten the current year’s sideshoots in August, stopping just short of a cluster of berries (usually two or three leaves up from the base).Cotoneaster
The flowered branches of summer-flowering cotoneaster may now be cut back by half their length. Oldest branches can be taken back right to the ground.
If you have a rambling rose grown up a building or support, pruning now will prevent it from overwhelming the space and maintain overall health. If growing up a tree, you’ll be glad to hear it can be left alone!
The approach is very simple. Remove a third of the oldest stems down to the ground, and then any weak, misplaced, dead, diseased, or damaged growth. Tie in new, vigorous shoots ready for flowering next year.
Check out our blog post on How to Prune Rose Shrubs for tips on how to tackle other types of rose.
Hebe and lavender
While you may be familiar with the guidance for pruning lavender, did you know hebe can be given the same treatment? In both cases, a light shearing now will prevent plants from becoming woody and scruffy.
Simply trim back faded flowers, also taking off around 2-3cm of foliage. Try not to cut too far down into the plant, as neither lavender nor hebe grow back from old wood.
Unless you have a flowering hedge (in which case, trimming is generally advised after blooming), August is the perfect month for hedge cutting. The birds have finished nesting, and now is sufficiently early in the year to avoid frost exposure on cut stems, yet late enough that there will be minimal regrowth before winter. The result is neat, healthy-looking hedges right through until spring.
Read our How to Trim a Hedge and Bird Nesting Season guides for more in depth information.
- Deadhead flowering shrubs
Keep deadheading late-flowering shrubs (including roses) to encourage continued flowering into autumn.
- Propagate shrubs
Now is a great time to take cuttings of many hardy shrubs, including box, ceanothus, azalea, and privet. Use shoots of the current year’s growth with a soft tip and woody base (known as semi-ripe).
- Plant flower bulbs
When it comes to bulbs, it really boils down to one simple rule - to plant during dormancy. This will vary depending on the flowering time:
- Spring-flowering bulbs are dormant in autumn.
- Summer-flowering bulbs are dormant in spring.
- Autumn-flowering bulbs are dormant in summer.
We are now in the tail-end of the autumn-flowering bulb planting season (these bulbs will bloom within weeks of going into the ground). Favourites include:
Often sugary-pink in colour with delicate, wavy-edged petals.
Love a sun-baked spot at the base of a sunny wall.
Goblet-shaped flowers, usually in shades of purple, pink or white.
Enjoy a sunny spot where the soil dries out in summer.
Crocus-like flowers in bright, golden yellow.
Prefer light, chalky soils and a dry summer dormancy.
Small pink, white, or purple flowers appear after the first rains of late summer.
Enjoy sun or light shade and a humus-rich soil.
Resemble super-sized crocus flowers, in pink, white, and purple.
Prefer a deep, fertile soil and full sun.
- Sow hardy annuals
The sowing of hardy annuals starts in earnest next month, though bending the rules slightly and sowing towards the end of August can result in beefier plants which flower ahead of schedule next spring. The one proviso is that special attention must be paid to watering in those initial few weeks, when conditions can be perilously hot and dry for new seedlings.
Suitable plants include ammi, nigella, honesty, cornflower, poppy, and flax.
- Cut back herbaceous plants
While autumn and spring are the main seasons for cutting back herbaceous plants, if you have limited time available it can be helpful to get things off to a head start in late summer. The plants themselves will helpfully indicate where to begin; anything that has already died back (e.g., dicentra) is now ready for attention.
- Propagate flowers
There is still time to propagate bearded irises by dividing their rhizomes. As well as increasing stocks of each plant, this has the added benefit of maintaining the health and flowering vigour of existing clumps. Aim to do it every three to five years. Tender perennials:
You will feel exceptionally pleased with yourself next spring if you take a little time now to propagate your tender perennials. Yes, argyranthemum, bidens, gazania, salvia and the like can be overwintered indoors, though, not only is this a faff, but the plants rarely look as good from year two onwards. Far better is to take cuttings and start afresh each year.
- Mow the lawn frequently but raise the cutting height
Grass sends its roots further down into the ground when left to grow longer, making it more drought tolerant and less likely to turn brown during heatwaves.
Read our How to Keep your Lawn Looking Perfect guide for more information.
- Keep ponds and water features topped up
A huge range of wildlife can be reliant on a water feature, whether that be as a place to live, drink, or bathe. It is therefore vital that things such as ponds and bird baths are kept topped up at this time of year, particularly if you live in a built-up area where other sources of water are scarce.
Read our How to Make a Wildlife-Friendly Garden post for more tips.
- Turn compost to encourage aeration and decomposition
While it is not essential to turn your compost heap (providing it contains a mix of woody and green material), doing so can significantly increase the rate of decomposition. At this time of year when compost heaps are likely to be groaning with the results of hedge trimming and constant deadheading, a helping hand to speed things up can be much needed.
If you have multiple compost bays, use a garden fork to move all material from the full bay to an empty alternative. For those with just the one heap, lay a large sheet of tarpaulin on the ground to allow you to move material out and back in again.
Pests and diseases
- Powdery mildew
Powdery mildew is a fungal disease which causes white, powdery patches to cover leaves, flowers, and fruit. It tends to occur where plants have been given insufficient sunlight or airflow, as well as exposure to drought stress.
At this time of year, the best thing you can do is to remove affected parts of the plant, keep it regularly watered, mulch with well-rotted organic matter, and improve airflow in any way possible. This may involve a light pruning of the plant and/or its neighbours, as well as clearing away surrounding weeds or debris.
- Rose black spot
If your roses have succumbed to the dreaded black spot (a fungal disease of the leaves with an appearance exactly as the name suggests), by now the affected foliage may be starting to turn yellow and drop off the plant.
For now, all that can be done is to collect and destroy the leaves. Later (towards the end of winter) prune out affected branches where possible, as well as applying a thick layer of mulch around the plant to prevent rain splashing soil-borne spores onto the new leaves. These actions may help delay the onset of the disease, though are unlikely to prevent it entirely.
Fungicides are available to tackle this problem, however The Hedgers recommend replacing affected plants with one of the many black spot-resistant varieties available.
- Vine weevil
Earlier in the year, you may have spotted the tell-tale notching of leaves caused by adult vine weevils, particularly on your container-grown plants. While unsightly, this is unlikely to have had any major impact on plant health.
We’re afraid to say the worst may be yet to come. Around now larvae begin to hatch from the eggs laid in the compost by those adults, unfortunately the most damaging stage. The little white grubs have a voracious appetite for underground growth and will often decimate entire root systems.
Clearly, the time for action is when adults are suspected earlier in the year. The most sustainable approach is to encourage natural predators into the vicinity, such as frogs, shrews, toads, birds, hedgehogs, and ground beetles. Evening torchlight searches can also prove fruitful, allowing you to pick off and destroy the nocturnal insects by hand.
Once the larval stage has been reached, check the compost regularly and remove as many grubs as you can. We also recommend applying a nematode – a naturally pathogenic microscopic insect. These usually come in a small tube or sachet and are available from online biological control retailers.
Read our 11 Popular Garden Pests and Diseases Found in Hedging Plants for tips on dealing with a range of other common issues.
We hope you’ve enjoyed our gardening tips for August.
Want to get ahead on your to do list? Find out what you can do in your garden in a September here.
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