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What to do in the ornamental garden in October 2011

Cold crisp mornings, the first frosts, shorter day length?  Yes, if October as we know and love it has arrived. After the late September heat wave predictions are perhaps unwise. As the heat followed on from a coolish  summer, some plants may think that winter is over and begin to flower again.

General tasks

• Heavy leaf fall can be expected this month. Rake leaves up and pile in a leafmould bin. Or, if you have a small garden, bag up and stash in corners here and there. Leaves can also be chucked at the base of hedges, or behind shrubs, where they will slowly rot down, while providing overwintering shelter for a huge range of wildlife.
• Re-turf or re-seed worn areas of lawn.

• 
  Hedgecutting
• Complete the cutting of hedges. Throw clippings underneath the hedge to provide winter shelter for insects and small mammals. Wait until next spring before adding to the compost heap.
• Lift and store tender bulbs such as gladioli, dahlias and cannas. Tender perennials such as salvias and pelargoniums should also be brought into a greenhouse. If this is not practical, cover them with a thick mulch.
• Bananas will need to be protected by now also. The best way of doing this is with horticultural fleece and bubble plastic. For more information, see our overwintering bananas page.
• Clear away diseased plant material but don’t be too tidy. Birds feeding on seeds will also consume aphids. Beneficial insects need somewhere snug to spend the winter months. Mulches, hollow stems, grassy tussocks and seed heads left in situ over the winter will provide food and shelter for a huge range of creatures.
• There is always plenty to compost in the autumn, so try to avoid the lure of the bonfire. If your compost bin is full, move the contents out and cover with a sheet of plastic. This frees up the bin to start a fresh heap. Alternatively, buy or build new one.
  Garden Organic members can view our factsheets online:

  • How to make compost
  • Building a compost box
  • Buying a compost box

  Access to factsheets requires members' password. Find out more about Garden Organic membership here.

• 
  Water rhododendrons
  in dry spells
• Water camellias, rhododendrons and azaleas in dry spells. A shortage of water at this time of year can cause flower buds to drop next spring before they open.
• Raise pots off the ground, using bricks, or pot ‘feet’. Prolonged rain can saturate pots, leading to root damage in waterlogged plants. Good drainage is essential in winter.
• Stop watering succulents indoors. They require dry growing conditions at this time of year. Keep them in a cool, sunny spot. Next watering should be in 2 months time.
• Cut roses back by about one third, to prevent wind rock. Tie in climbers for the same reason.
• Prune out shrub or tree branches that are likely to be blown against any structures in high winds.

Greenhouse

• Thoroughly clean the greenhouse, inside and out. No need to sterilise all the surfaces - a good wash and scrub with a stiff brush will suffice. Sweep spiders away first and release them outside – they are beneficial in the garden so need to be rescued. Choose a sunny day for this activity. It’s important that everything dries off before you shut the doors for the evening. If you have a power washer the job will be very easy, but remember to remove plants before you start.
• Put up 'bubble wrap' to insulate the greenhouse over winter. Keep some cut lengths of fleece to hand, to cover vulnerable plants on cold nights.
• If you plan to use heat, no need to heat the entire greenhouse if you only have a few plants. Use several layers of bubble wrap to make a thick screen and just use heat one small area.
• Check all heaters to make sure they’re working efficiently.
• Remove any leaves showing signs of mildew or grey mould. This is a prime time for fungal diseases to germinate.
• Give all overwintering plants a good check over for pests and diseases before bringing them indoors. Scrape off the top 1 cm of potting compost and replace with grit. Cut back top growth showing any signs of leaf roll or webbing.

Lawn Care

• Reduce the frequency of your mowing as the weather cools and the growth of the grass slows.
• Raise the cutting height of your mower . This helps the lawn cope better with the cold winter months.
• If trees shed leaves on the lawn, mow over them, then rake everything up and add to the leafmould pile.
• Complete autumn lawn care, including scarifying, aerating and re-seeding. More information on autumn lawn care can be found in the September archive.

Ponds

• It’s too late to clean out the pond now, water creatures will probably have settled in for the winter. Just cut back overgrown plants, and divide those that need it if you haven't already done so. Cover the pond with netting to catch autumn leaves. Pin netting down with bricks, make sure it’s tight so birds don’t get caught, and leave a gap between some of the bricks so frogs can get in/out underneath.

• Garden Organic members can view our factsheet, Troubleshooting in the Garden Pond
  
  Access to factsheets requires members' password. Find out more about Garden Organic membership here.

What to Plant in October

• 
  Bluebells
  
  
• Plant bulbs for flowering next spring. If mail order bulbs arrive and you aren’t able to plant them immediately, unpack from their box, and either spread out in a seed tray, or hang up in netting. They need to be kept ventilated. Bulbs that sprout before planting should be handled carefully to avoid damaging the shoots.
• If you’re a bit late planting bulbs, don’t worry. Research has found that as long as bulbs are planted by November, they should flower well.
• Tulips should be planted no earlier than November. This avoids the infective phase of the disease tulip fire.
• Before you plant up containers, put in a thick layer of shingle, about a quarter of the container’s total depth. This prevents frost from cracking the pot.
• Containers can be planted up with bulbs. Planting depth will depend on the bulbs chosen.  Spring or summer flowering plants can be added so that the display will have year-round interest.
• Pansies often disappoint in winter. They can be ruined by aphid attack, especially in dry weather. Wind knocks them about, and they often don’t start looking good until just before it’s time to clear them out for early summer displays! Violas seem to perform better over winter. They tolerate shady conditions well and will brighten up drab corners of a winter garden.

 If you use herbs in containers, add some horticultural grit to the potting compost. About 1 part grit to 4 parts compost. They grow better in well-drained conditions.

Make New Plants

As the ground is still warm, this is a good month to lift and divide plants that have either outgrown their space, are looking tatty in the middle, or that are just in the wrong spot.

Lift and divide

• Cut plants back to 3cm-5cm (1"- 2"), then loosen all around with a fork.
• If necessary, protect lawns or paths with a sheet of plastic.
• When the plant has been sufficiently loosened slide your fork under the plant and lift. You may need 2 forks (one from each side) if it is a large plant.
• Place the plant to one side on the ground (or the plastic sheet) and look for natural lines across the plant. Use a sharp knife to divide it into chunks. Make sure that each section has plenty of roots along with the top growth.  If the plant is particularly tough, a saw can be used to cut through the fibres.
• Discard any woody centre.
• To replant, dig a hole slightly larger than your plant, add some home made compost to the hole and mix it in. Plant in the centre of the hole, fill in around and firm gently.
• Water in well.
• Plants left over can be potted up and offered to friends, schools, the local WI market.

Seed sowing

Clematis seed heads will be ready for sowing now. Once they are fluffy, they are ripe.

• Cut the seed head from the plant, leaving a small amount of stem attached.
• Mix some potting compost with grit, 1 part grit to 4 parts compost, and fill a medium size pot. Leave a 2cm space between the pot rim, and the compost.
• Bury the clematis stem in the compost until the seed head touches the surface of the compost. It must make contact.
• Alternatively, you can separate the seeds from the seed head and scatter them all over the surface of the potting compost.
• Cover the seed head/seeds with a thin layer of grit.
• Place the pot in a sheltered spot in the garden and leave until next spring. You can also keep the pot in a cold greenhouse, but remember to keep moist.
• Check in early/mid March for signs of growth. Seedlings should start to push through round about then.
• Once seedlings are big enough to hold, they can be potted up into individual pots, ready to grow on and be planted out later in the year. Lift out very carefully as the roots will be tiny.

Sweet peas can be sown in pots too. They will grow steadily through the winter, and be ready to plant out in early spring.

• Sow seeds, well spaced out, in a large pot.
• As they germinate, push in a stick alongside each seedling, so that they can be tied in as they grow. This stops them getting tangled and makes it much easier to separate at planting time. Florist’s thin sticks are ideal for this job.

Keep pots moist, but not saturated, over winter.

Lots of other seeds are ripening at this time of the year. Try sowing them in pots or trays using the same method. It’s a great way to increase your plants, at no cost.

Star Plants for October

This month, many trees and shrubs are displaying their beautiful autumn colours, so if you are looking for inspiration, here are some ideas

• Acer palmatum 'Garnet' is one of the most popular of the Japanese maples. It has stunning red-purple, finely dissected foliage. It only grows up to around 5 or 6 feet tall making it suitable for the smallest of gardens and can also be grown in a container. Grow it in a sheltered position away from strong winds in moist, fertile soil.
  
  
• Rhus typhina is a justifiably popular shrub. It is also known as the Stag’s Horn Sumach due to its soft velvety branches. By this time of year, the leaves have turned to a gorgeous orange-red and will really brighten up a dark corner of the garden. It will reach a maximum height and spread of around 15 feet.
  
  
• Cotinus 'Flame'. The common name for this small tree is the Smoke Bush because it produces long panicles containing hundreds of tiny flowers during the summer. From a distance these look like clouds of smoke emerging from the tree. In October the leaves will have turned from light green to a brilliant orange-red. It will eventually reach a height of about 20 feet.
  
  
• Cercidiphyllum japonicum var. magnificum puts on one of the best autumn displays of any tree. Its leaves change from green to yellow to bronze then orange and red. These array of warm colours have an almost toasted look to them and this is complimented by the smell which they give off as they fall – burnt sugar. When full grown it will make a fine specimen at 30 feet tall.

  Unusual plants can be sourced by using the RHS plantfinder on-line. There is a listing of organic nurseries too.

  Our organic guidelines give information on sourcing organic plants

  
  
  

Pest & disease watch

• 
  Vine weevil adult and larvae
  
  
  Rose blackspot
  Diplocarpon rosae
  Squirrels love digging up newly planted bulbs. Protect pots and new plantings with a cover of small mesh chicken wire now. Remove it when new growth is poking through the soil in spring.
• Check pots for vine weevil larvae. They will have hatched by now, and will feed on plants’ roots through the winter. Fuchsia in pots will definitely have been infested. Tip out all the compost and put it into the green waste recycling. Scrub the container and pot up plants with fresh potting compost.  Check plants’ roots thoroughly before re-potting.
• Rake up leaves under roses to prevent blackspot spores over-wintering in the soil. Affected leaves have dark brown or black, often coalescing, blotches on both leaf surfaces. Prune out infected shoots and remove any remaining leaves before they fall.
  Garden Organic members can view our factsheet, Rose blackspot for more details
  
  Access to factsheets requires members' password. Find out more about Garden Organic membership here.

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