Monthly Advice - September Jobs in the Garden

Jobs for September


  1. Little needs to happen to your hedges in September, assuming that you did actually prune them in August. It is always worth checking hedges for damage from animals, footballs, bad that you cut out/clean up any diseased or damaged wood before any fungus or virus can get a grip.
  2. Keep an eye on the watering of anything that has been planted this year and anything in baskets, pots, boxes and other containers. 
  3. If you are planning a new hedge, then it is time to get busy. If you are happy using a weedkiller such as Roundup, then mark out the area to planted and weed-kill it. Absolutely worth doing as it will save you so much time later. If you do not want to use a weedkiller, then think about using a weed-proof membrane such as our Mypex - watch our video on how to plant a country hedge to see how to apply it.

Fruit Trees

  1. Where possible keep protecting any ripening fruit by using netting. Make sure it is secured tightly so that you do not trap birds in it.
  2. Dessert pears are best picked unripe and left to develop unwrapped on slatted shelves so that the air can circulate. Bring in a few to the warmth of the kitchen and watch them like a hawk because pears go from unripe to woolly in what will seem like hours. A ripe pear will give slightly around the stem but should  in no way be squashy. Once ripe, you can store them wrapped in newspaper in the fridge. Experiment with recipes that involve blue cheese or cook pears with blackcurrants frozen earlier in the summer. Check on the website when your pear variety is due to ripen; many should be picked towards the end of September. 
  3. Apples should come away from the tree with a gentle twist if they are ripe. They are surprisingly fragile and easy to bruise so treat them gently and store only the ones that are perfect. You can do this either by wrapping them in newspaper or leaving them unwrapped. Place them in a cardboard box or on a shelf but if unwrapped, do not let them touch one another. Use up any bruised fruits, or windfalls (mind the wasps!) first. It is not essential, but is quite efficient to prune your fruit trees as soon as the fruit has been picked.
  4. Any surplus plums or damsons that have gone over should be collected up and left in a pile somewhere for butterflies to enjoy.

 Garden trees and shrubs

  1. Assiduous gardeners spend a great deal of their time moving plants around when they see a gap or a better position for an existing plant. If you were planning on moving any evergreen shrubs - laurels, cotoneasters, privet, holly, pyracantha, box, yew or berberis - do it now when the soil is warm and you get the benefit of the early morning dews for moisture. Dig around the plant as far and as deep as you are able so that you can move as generous a rootball as possible. Rock the plant backwards and forwards to loosen it and, if possible, slide a piece of plastic or hessian underneath the roots to help you move the whole bang shoot. The covering will also keep some of the moisture around the roots diminishing the shock to the plant as you move it. Make sure that your new planting hole is big enough to fit in all of the roots and rootball comfortably and that once your plant  is settled in,  it is planted at the same level as before.  Stake if necessary and water well. It is as well to put up some shelter in a windy site so that your shrub or tree can manage to keep all of its leaves hydrated against drying winds . A couple of stakes to the windward side of the plant with some hessian or plastic mesh stretched between them should do the trick.
  2. The warm soil and damp mornings also make autumn an excellent time to plant new container grown trees and shrubs. It is less time consuming for you because you will have to do less watering than planting in spring and it means that your plant will get off to a flying start next year having acclimatised to its new position over autumn and winter.
  3. Any shrubs like Philadelphus, Viburnums or Eleagnus that have been unlucky enough to be beset by mildew or aphids should have their shoot tips pruned back to healthy growth. Burn the clippings.
  4. Trees that have been grafted may start to produce suckers from more vigorous root stocks. These suckers need to be pulled off (as in torn away) ideally; snipping them off just encourages them to grow back.
  5. Trees or shrubs in pots no longer need any fertiliser as it encourages  soft and sappy growth that is easy prey for pests and diseases in winter. Instead give them a last feed with sulphate of potash or rock potash to ripen any wood ready for the winds and cold of winter.


  1. If your climbing rose is no longer producing flowers - and bear in mind that sometimes they can keep flowering until November - prune it. Start by using sharp secateurs and remove any stems that are dead, damaged or look unhealthy. If there are any signs of disease on it, you are best to burn the prunings so that you do not infect your compost.  Inspect the base of the rose for strong new shoots that have grown this year and tie them in to the wall or trellis so that they cover a "new" area of your support. At the same time remove any very old shoots from the base to allow more room for new shoots in the future.  Now look at the basic framework of the rose and take back any sideshoots from the main stems to two to three buds.
  2. Keep deadheading any other shrub roses to maintain the shape of the bush.
  3. Ramblers, Rosa rugosas and some wild roses will start producing hips to admire throughout autumn. You can make rosehip jelly with these...and then there is of course the itching powder option.....
  4. Remove any suckers from the base of roses and where you have had blackspot or any fungal problems sweep up the leaves and burn them rather than leave them to compost where they are, or to include them in your actual compost.
  5. Order your bare root roses now before anyone else does so that you can guarantee you will get your rose of choice.

Soft Fruit

  1. Autumn fruiting raspberries have the edge on summer fruiting in my book, and as of mid-September you should be harvesting yours. Leave the canes unpruned once you have harvested all the fruit you can; pruning them back is a late winter job.
  2. Summer fruiting raspberry canes that have fruited need to be removed. The new canes that have grown this year should be tied in securely so that they will not be affected by winter weathe


  1. Autumn is a fine time to plant container-grown climbers like clematis, honeysuckle or jasmine.



  1. Ideally lavender should have been trimmed in August, but September may just have to suffice. Remove the spent flowers and take off a tiny bit of the current year's growth to maintain a bushy appearance. Without this trim your lavender will become leggy and will need replacing sooner than it needs to.
  2. If you have an old lavender hedge that is really past its sell by date, then grub it out now. You can replant lavender where ti grew before, but it does much better if the soil has had a few months in which to rest. 


  1. Planting bulbs is, no doubt about it, time consuming. So for smaller bulbs or corms the quickest way is to use a half moon edging tool to cut a section of turf,  peel it back and place the small bulbs underneath before laying the turf back over again. Larger bulbs need to be planted 2-3 times their depth below the soil to ensure that they flower and will come back again and again. To prevent your planting looking municipal in any way, throw a handful of bulbs over the grass where you plan to naturalise them and then plant the bulbs where they fall. Clay soils require a little grit at the bottom of the planting hole and, for all bulbs, a little bonemeal added to the soil never comes amiss.
  2. And as to how many bulbs you need, it is worth working on the following numbers per metre squared for a pretty dense and impressive planting scheme:
    • narcissi or daffodils about 40-60
    • 100-150 crocus
    • 30-40 camassia
    • 15-20 large alliums like Purple sensation or up to 100 for the smaller alliums
    • And, sigh of relief, tulips can wait until late October or November.....but you will need between 40 and 60 bulbs per square metre (and order now to avoid disappointment later).
  3. As discussed in August Jobs, now is your very last chance to plant bulbs so that they might be ready for Christmas. You have been warned! Hyacinths and Amaryllis are the traditional choices but there is no reason not to pot up some of the smaller bulbs like chionodoxa, crocus or anemone so that you have lovely flowering things going on inside throughout winter.
  4. Gladioli fanciers should lift the corms once the leaves go yellow. After the leaves have gone yellow and withered, cut them down to 2-3 inches and remove the old used part of the corm. Hang onto any little baby corms that have developed because you sow them just like seeds in a seedtray of compost next spring to increase your crop.

Olive and Bay Trees  

  1. Feed once a month and water regularly so that the soil never dries out.

Other – to include soils, lawns, ponds, terraces

  1. Outdoor grown tomatoes may not have reddened yet. Hasten their ripening by laying the plant down on some straw and putting a cloche over the tomatoes to concentrate the effects of the sun.
  2. All chefs agree that fresh herbs make an enormous difference to the success of their cooking. For the winter sow some chervil, both types of parsley, coriander and dill inside to germinate. Then plant them outside if the weather is not too cold after a few weeks. And use up some of the last of your existing herbs: a few sprigs of tarragon in a bottle of white wine vinegar will keep for ages and makes wonderful hollandaise sauce and tangy salad dressings.
  3. Get a headstart for your spring flower borders by sowing some hardy annuals now so that they are already up and running to flower in early May. That way you will see less of a "gap" between the end of the bulbs and the beginning of the summer flowers. Seeds to sow include Cerinthe, Calendula, Centaurea and some poppies. Check the seed packet and if you are gardening on clay you might be advised to sow into modules and keep them in a green house; the wet of clay inclines seedlings to rot over winter. 
  4. Pick the last of your pumpkins, marrows and squashes and leave them out in the sun to ripen and dry off so that they will last until Christmas. If the weather is wet, store them in a greenhouse for a few weeks. Clear away the remaining plants because they will probably be mildewed by now.  And then look up lots of chutney recipes for any crop that you do not think will last!
  5. Garlic should be planted in the autumn. Break open the head of garlic and plant each clove individually so that just the tip of the clove emerges above the soil. Keep checking that the birds do not move them around out of curiosity.
  6. At long last the lawns should not be growing so robustly so you can cut down the amount of times you need to mow. Throughout autumn you should try to scarify your lawn. The energetic will use a spring-tined rake to eliminate the thatch of dead grass, moss and other debris that has built up in the lawn. Anyone with a larger lawn should hire a scarifier to do this back breaking job. The lawn will look awful immediately afterwards but it will improve very quickly and scarifying prevents weeds and moss taking hold. Next up is to aerate the lawn because grass needs air. Either hire another machine or push a fork 6 inches into the ground every 9 inches or so. Aerating compensates for all the compaction of mowing and general lawn use over the summer . Finally top dress your lawn using sharp sand, compost and soil and maybe adding some grass seed if it is looking a bit worn. If that is a step too far, a feed and weed product suited for autumn use will probably do. If you need to re-seed a bare patch it is worth mixing the seed with multi purpose compost, scattering that over the raked area and then pegging some polythene over the whole shebang to encourage germination.
  7. For those who garden on clay, you could try to improve the soil in your beds by digging in pea shingle and organic matter now before the soil becomes claggy. the winter weather will break down any lumps and the added materials will make your soil easier to work next year. Doing this will improve the drainage and will also raise the beds a little so that they warm up more quickly and you can start sowing vegetables or flowers earlier.
  8. If you have insufficient compost bins then build your own by knocking in four stakes at each point of a square. Attach chicken wire around three sides and line the wire with cardboard from all of those internet deliveries to keep the heat in. Cover the vegetable trimmings, shredded paper, and all the other multitude of compostable material with an old carpet....perhaps that one one from the souk in Morocco that does not look quite so good here after all.....and within a year you will have your own friable compost to put back onto your beds.
  9. The final boring job is to clean out your green house so that you can overwinter plants in it without fear of pests. Use a diluted household bleach to get into all of the corners and to wash down the glass panes to maximise the light in the greenhouse over winter.



Tags: advice  September 
We do use cookies, which are bits of code that stay on your browser. They help you to buy products from us online in a convenient and secure manner, and help us to improve and give you the smooth service that you desire.

Thank you, The Ashridge Nurseries Team.

Back to top