Gardening Advice for Mid-August to Mid-September

The end of summer is often a magical time bathed in golden light and sunshine.  Here’s hoping the month ahead is a lovely time, there’s certainly a lot to do to keep you busy!

Vine weevils are a real pain, especially if you’ve got lots of container grown plants, the adult weevils damage plant leaves, leaving a notch-shaped, irregular edge to the leaves, resulting in a bit of a ragged looking, untidy plant.  This is annoying, but far worse is the damage that the immature weevil grubs cause to the roots of plants.  The adult weevil lays its eggs in the soil, often in containers, but in garden soil as well, throughout the summer.  The eggs hatch, and the developing creamy-white, brown-headed grubs live in the soil, feeding on plant roots.  At best vine weevil grubs will weaken the plant, and worst case scenario they will kill it, so it’s wise to take action to protect your plants.  This is very easily done, using a biological control – a concentrated amount of the Vine weevil’s natural predator – Steinernema kraussei, a microscopic eel worm, a nematode that occurs naturally in our soils.  It’s very easy to order packs of these nematodes online, which are then posted out, it’s best to apply the nematodes as soon as they arrive, but they can be stored in the fridge for a limited time, usually a week or two.  It’s worth noting that the eel worms live in the moisture surrounding soil particles, and will require moist soil to enable them to swim through the soil and seek out the vine weevil larva.  So you will need to increase your watering regime before application, and for at least a few weeks afterwards for maximum success.  This is a job you don’t want to be too early with as the nematode is effective only on the weevil grubs, it will not eat the eggs. If the vine weevil larva are not present in the soil, the nematode will die out, but no damage will be caused to your plants.

Strawberry plants are not as healthy or productive once they reach about four years old, so it’s worth discarding your older strawberry plants and starting a new strawberry bed in a different area of your garden or allotment.  If you grow fabulous strawberries then it’s worth planting their new season runners to enjoy next year, but if your strawberry season is particularly short, or if you were not impressed with the taste of your fruit, then now is a good time to select varieties for a taste sensation and longer season next year.

I carry out strawberry trials on my allotment each year, trying new varieties, selecting favourites to grow again, and discarding ones that don’t pass muster.  I aim for a long cropping season, but my priority is the taste, my strawberries have to be delicious!  The varieties I grow include perpetual, early, mid and late season varieties.  I love Mara de bois with its wonderfully intense flavour and pineberries for their slightly sharper pineapple flavour and white fruits, it’s wonderful to grow fruit you cannot buy in the shops and which really have an intense flavour.  I also grow ‘Christine’, ‘Sweetheart’, ‘Gariguette’ and varieties of alpine strawberries.

When your strawberries have finished cropping for the summer, cut back all of their tired old leaves, right down to ground level.  If you surrounded your strawberry plants with a straw mulch, remove this now – it will make a fabulous addition to your compost heap.

If you would like to grow more plants beneficial to bees and other pollinating insects, then now is a good time to sow single flowered forms of Calendula officinalis (Pot Marigold), Papaver rhoeas (Poppies) and Centaurea cyanus (Cornflower).

I am passionate about protecting bees and other pollinating insects; as well as being rather lovely, charming and hardworking little creatures, we are dependent on bees for the pollination of crops and livestock feed.  The economic value of honey bees and bumble bees as pollinators of commercially grown crops in the UK has been estimated at over £200 million per year.  We need to protect, look after and appreciate bees – they need nectar rich plants which are accessible through the year while they are active, so it’s worth bearing this in mind when you’re choosing your plants, buying and sowing seeds.

If you have, or are planning a meadow, sow Yellow Rattle (Rhinanthus minor) seeds into scarified patches of bare soil closely surrounding grasses now. Yellow Rattle is semi-parasitic on grass; it weakens grass a little, which allows other meadow flowers to establish themselves.  Other meadow flowers and seed mixes can be sown now, although on heavy clay soils it is worth delaying sowing your seeds until spring time.

It’s the perfect time to prepare and sow new lawns.  It’s important to remove all weeds, particularly perennial weeds before you start your lawn preparation.  It’s a good time to evaluate your lawn and sow grass seed in any bare patches or lay turf if needed; make sure you have selected a seed suitable for the type of lawn you want to grow and for the conditions present.  Store the grass seed in the freezer for a few days before sowing, the sudden change in temperature will help the seed germinate more readily.

Sow green manures like grazing rye (Secale cereal) Mustard (Sinapis alba) and Winter tares (Vicia sativa).  Ensure you do not sow Mustard, which is a brassica, before or after other brassica crops because of the increased risk of clubroot – it’s worth looking at your crop rotation plan before deciding where to sow.

If you’ve got a greenhouse, conservatory, or polytunnel, you can plant potatoes now to harvest at Christmas, you can also try growing them outside if you have a warm and sheltered spot in your garden.  If you’re growing outside, I’d recommend adding lots of extra fertiliser early on to get the potatoes to grow as soon as possible, and use a cloche or protective cover to keep the leaves protected from becoming too wet, as well as protecting against frost.

Growing potatoes in pots or bags is a great idea, and very successful too.  You’re spared the hassle of having volunteer potatoes popping up the following year and you can easily move the container or bag if you need to.  It’s worth noting that you always water from the top of the bag, and avoid watering the potato haulms or stems.

Outside: sow endive, lettuce, Japanese onions, winter hardy spring onions, peas, pak choi, radish, spinach, turnip, and winter radish now.

Plant shallots, kale, and winter cabbages.

Plant: Cyclamen, Daffodils and Narcissus, Erythronium, Lily, Nerine, Scilla, Trillium, Autumn Crocus, and Meadow Saffron (Colchicum autumnale).

Prune rambler roses after they have finished flowering, remove the old stems at the base of the plant, and reduce the new shoots by a third, to encourage new side-shoots to form and produce more flowers for next year.

Take semi-hardwood cuttings of Berberis thunbergii, Pyracantha, Honeysuckle, Rosemary, Lavender, Viburnum opulus and Ceanothus now.

Take root cuttings of Eryngiums and oriental poppies.

I hope you get time to soak up this lovely time of year and enjoy the month ahead in your garden.

This article was first published in the mid-August 2013 edition of The Surrey and Hants News.

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