Garden Maintenance: SEPTEMBER
Top gardening jobs for September
1. Divide herbaceous perennials
2. Collect and sow seed from perennials and hardy annuals
3. Clean out greenhouses so that they are ready for use in the autumn
4. Start to reduce watering of houseplants as light levels drop.
5. Order spring flowering bulbs.
6. Take semi ripe cuttings of evergreen shrubs if you want to propagate them.
- The weather is still suitable for creating and repairing new lawns with
turf or seed. But you are running out of time to use lawn weedkillers to
control perennial weeds such as daises and buttercups.
- You may need to strengthen your lawn for winter by applying an autumn lawn feed which is high in potassium to strengthen the roots. Avoid using old summer feeds as these are high in Nitrogen which at the wrong time of year could encourage lawn diseases.
Trees, shrubs and climbers
- Shrubs that flowered early in the year (Camellia and Rhododendron)
should continue to be well watered to ensure a good flower display next
spring. Remember to use recycled water wherever possible.
- Prune climbing roses once they have finished flowering, cutting sideshoots back a couple of buds from the main frame.
- Late-summer flowering shrubs such as Helianthemum (rock rose) can be pruned this month. As a very general rule prune flowering shrubs either before or after they have flowered.
- Take hardwood cuttings of roses.
- Keep trimming hedges as required to keep them tidy.
- If there are strong winds, beware of falling trees. Trees that still have their leaves are easily blown over in strong winds - especially as wet soils make trees less stable.
- What some people call a weed others call a wildflower; if you like it
then why not look for the seed heads to ripen then pluck off the heads and
shake them over a chosen area where you would like to have wild flowers next
year. Poppies for example take easily from casual sowing like this. Same
applies to your more traditional perennials.
- Buy or order spring-flowering bulbs. Daffodils are traditionally planted September/early October for best results. Tulips are best left until November. There are many other bulbs to choose from so visit a garden centre to see whats available.
- Its okay to plant new perennials as the ground is still warm but moist and they will have time to establish before winter. You can also buy spring-flowering bedding plants such as Bellis, Primula, wallflowers, and violas.
- Continue cutting back any perennials that are fading and dying down. Deadheading plants such as Dahlia, Delphinium and Penstemon will prolong the display and give colour well into the month.
- Your hanging baskets will also benefit from a little deadheading and feeding to keep them going until mid-autumn.
- Divide any overgrown clumps of alpines and herbaceous perennials (such as crocosmias) to invigorate them and improve flowering next year.
- You can still apply weedkillers to kill most perennial weeds.
Greenhouse and Houseplants
- If you use your greenhouse then remember to clean it before you fill it with plants you want to protect from frost over the winter. Hose it down and then use a safe cleaning product such as Citrox to kill off any pests.
- Submerged oxygenating plants may need thinning out as they can quickly
build up and fill the pond.
- Remove dead leaves from waterlilies as the leaves die back. Now is also a good time to divide waterlilies (and other pond plants) to increase your stocks and control vigorous growth. Ideally planting should cover no more than 50% of the waters surface.
- If you use your greenhouse then remember to clean it before you fill it
with plants you want to protect from frost over the winter. Hose it down and
then use a safe cleaning product such as Citrox to kill off any pests.
- If the weather ever dries up take advantage of it by painting fences, sheds and other wooden structures with a preservative. Remember that old oil-based products are no longer legal to use; our members have a list of banned chemicals if you are unsure.
- Replacing broken glass in your greenhouse is a good idea before the serious rain sets in. Fix leaky shed roofs for the same reason.