• This week’s cold snap is a reminder that summer really has gone for this season and you mustn’t delay on getting the winter vegetables into the ground. You have missed the boat on brussels and main crop carrots, parsnips and leeks but you can still plant all the brassica family, Florence fennel, spinach, peas and winter salad vegies.
• Make sure you get around to collecting your harvest of onions, pumpkins and anything else that is ready. It doesn’t do them any good left lying in the open, especially with the rains.
• If you have spare ground in the vegetable garden, sow down a green crop for winter – lupins, oats or rye. Continually cropping the same ground strips out the goodness from the soil and digging in a green crop later is a much better approach to replenishing the fertility and improving the soil texture than relying on artificial fertilisers.
• Sow annuals for winter and early spring flowering into trays now, if you want an early start. It is much cheaper to buy seed than plants. Annuals such as pansies, poppies and cornflowers are easy to grow from seed but you need to get them started in trays and then transplant them into the garden when they have a bit of size and a good root system.
• It is very close to your last chance to prune cherry trees and plum trees this season. Don’t leave it any longer because winter pruning makes them vulnerable to disease, particularly silver blight.
• It is a good time for taking cuttings of easy to root plants such as fuchsias, vireya rhododendrons, many perennials (ones like pinks and carnations which don’t clump) and even hydrangeas. All these can be rooted without special facilities. Select new growth which is firm and doesn’t snap when flexed, make a clean cut at the base, take a sliver off the bottom 2cm of the cutting (two slivers either side for a vireya) and put into potting mix, preferably one without fertiliser added. Not all plants are easy to root. In fact some are extremely difficult and without a home propagation unit (a hotbed) you are unlikely to succeed with most trees, rhododendrons, camellias and the like. Sadly, most fruit trees are budded or grafted and those that are done from cutting are not likely to root easily for the home gardener.
• Readers who recall the story last year on the local importers of Italian heirloom vegetable seed may be interested to know that their website is now up and running at http://www.italianseedspronto.co.nz. It is the wrong season for all those delectable tomatoes, basil, aubergines and the like (these are crops to sow in spring) but they do have some interesting brassicas, radicchio and finocchio (the latter being fennel bulbs).

The quote for the week comes from the late, great American architect, Frank Lloyd Wright:

A doctor can bury his mistakes but an architect can only advise his client to plant vines.

·         If you have outdoor grapevines which you have not yet covered, get the bird netting on as a top priority if you want any crop at all. The birds will eat them at an earlier stage than you and will completely strip the crop or open up the fruit for wasp attack.

·         A reminder to prune the fruited canes off your raspberries, if you have not yet done so (and we haven’t). If they have borne fruit this year, they are now redundant and merely clutter the place up because next summer’s fruit will be set on this season’s fresh growth.

·         Do a feeding round now on fruit trees, both deciduous and citrus. Feeding deciduous trees such as apples and plums now gives them time to take up the sustenance before they go dormant. If you are avoiding ready mix fertilisers, rich compost can be used but don’t build the layer up around the trunk.

·         March heralds the start of autumn. While we can expect a very long and mild autumn in our climate, getting the winter vegetables in should be a priority so they can do all their growing done and then most will just sit and hold in the ground when the cold weather comes. Winter vegetables take in the brassicas, winter spinach, peas and root crops such as carrots, swedes and parsnips. Sow the root crops first because they need longer to grow and it is getting late for them. It is the late winter and early spring vegetables which are the most expensive to buy so successional sowings now will save money later.

·         Gardeners in colder, inland areas should be starting to think about a pruning round on hedges because the plants are happier if they can make a small amount of fresh growth before colder temperatures stop them from growing until spring. The trick is to get the timing right so that growth is just a neat fresh flush and not a full on growth which will look untidy in winter.

·         A buxus expert we spoke to this week tells us that buxus blight (which turns the plants brown in big, spreading patches) is made a great deal worse by feeding and watering. Plants which are grown in drier, harder conditions will stay healthier. She also thins her plants to keep air movement. If you want to try and hold buxus blight at bay, don’t let your plants get too dense. She confirmed the advice we gave readers earlier: if you have a bad infestation, burn the plants and replace them with something different. Long term, there is little chance of beating buxus blight so the sooner you bite the bullet, the sooner you get other plants established.

·         Henry Mitchell, the deceased garden columnist for the Washington Post, wrote as recently as 1998: “There is a dangerous doctrine – dangerous because it precludes endless gardening pleasures – that every plant in the garden should be disease-free, bug-free, hardy to cold, resistant to heat and drought, cheap to buy and available at any garden centre.” Nothing has changed in the past decade, except that the plant is now expected to be low maintenance as well as all of the above.

• Gardeners who prefer ornamentals to vegetables will be pleased that the heat of summer is disappearing and we have had some rains because it means you can get back into the garden. The summer rest is almost over. You can be dividing spring and early summer flowering perennials at this time, but if you dig up entire clumps, water them back in. Perennials do much better in well cultivated ground and when they are not too congested and solid. If you are a novice and wondering what a perennial is, they are the clumping plants without woody stems and trunks which build up below ground with many growth points – plants like begonias, bergenias and most of the daisy family.
• Get on to lifting and dividing spring bulbs now because many are starting to put out fresh white roots.
• Deadhead agapanthus as they finish flowering if you have plants bordering streams or reserves. They are such a significant part of our summer landscape that we would be the poorer without them but some seed alarmingly and we don’t need them classified as a noxious weed, as in Northland.
• • If you have plans for laying fresh lawns this year, start work on them now by levelling and getting rid of weeds. It is too early to sow seed or lay lawn but the effort made now to drastically reduce resident weed seeds will pay dividends when you do get your lawn in.
• Do not think you will green up dry, tired looking existing lawns by sprinkling fertiliser at this time. You are more likely to kill the remaining grass. Wait for the rains to come and then get out the fertiliser if you must. Using a mulcher mower means that you don’t usually need to fertilise. You can deal to flat weeds in the lawn at this time, either by hand (an old carving knife is a good tool) or by selective sprays if you are still using them.
• In the vegetable garden, it is time to be a busy beaver getting in crops for winter. Sowing a few cabbages, cauliflower and broccoli each fortnight is better than doing one big hit because you want them to mature in stages. You can also be planting winter lettuce (which is leafy not hearting), Florence fennel (truly the most versatile of vegetables), beetroot, peas, green beans and carrots. It is nearly the end of green bean time so give these priority.
• Sow micro greens in a tray if you want a delicious quick turn around of salad veg which would cost you a great deal more to buy. At this time of the year, it is only a matter of weeks before you can start harvesting tender leaves.
• If your monarch caterpillars have stripped your swan plant supply, you can raise the larger sized caterpillars on pumpkin. Watch where you are walking because they will migrate in search of more food and they will also chrysalis sooner when faced with the threat of starvation.

It being harvest time for sweetcorn, the Curious Gardener’s Almanac tells us not only that sex is good but not as good as fresh sweet corn (!) but that if you lack kindling wood, the stalks of sweetcorn plants when dried and stored make excellent firelighters.

• The spring flowering bulbs we have been lifting from the garden are resolutely dormant but the pots in the nursery are already showing fresh white roots. This is because the nursery is under irrigation and it is the advent of autumn rains which triggers most spring bulbs into growth. The message is clear – don’t delay on lifting garden bulbs that you plan to divide. The early March rains are likely to send them into growth and you will damage the young roots if you leave it too long. This includes bluebells (do these first) and daffodils.
• The rain bucketing down here today has been greeted by Mark’s usual response: “Good news. There will be no drought this year.” But when the fine weather returns, keep up daily watering on container plants and don’t be forgetting to top up the goldfish pond if you have one. Fish get stressed when the water is too warm.
• In the height of summer, lettuce, rocket and mesclun tend to bolt to seed before maturity. With cooler weather just around the corner, it is safe to return to planting these crops with a reasonable expectation of a harvest.
• It is time to be getting in the late autumn and winter crops. Leeks are the most urgent crop to get in. Root crops such as carrots, parsnips and swedes if you fancy them can still be sown from seed now. The brassica family and Florence fennel will give the winter greens and can all be planted. Some people recommend getting broad beans in this early though it is usual to leave them until April. Dwarf beans can still be planted.
• While seeds are considerably cheaper than plants to buy, you can be even more economical and save seed of many crops. Clean the seed as you harvest it and store it in recycled envelopes with the date and variety written on the outside. Make sure the seeds are kept dry and, above all, away from anywhere the little autumn mice can locate them. Mark is using an old fridge (switched off) for this purpose. Any plants which are labelled F1 hybrids will not come true from seed but most crops can be grown from home harvested seed. The original seed packet will tell you if it is an F1 hybrid.
• Those of us who raise our eyebrows at the hyperbole of some people’s garden descriptions may enjoy Edward Augustus Bowles who wrote in 1914: “How magnificent it sounds! That is the fun of writing of one’s garden: a steep bank can be a cliff, a puddle a pool, a pool a lake, bog and moraine sound as though a guide were needed to find your way across them, and yet may be covered by a sheet of the Times. My Dolomites lie within the compass of my outstretched arms.” Mark has always been of the view that by definition a lake is a body of water sufficiently large upon which to water ski. Anything smaller is a pond.

• Tuesday’s rain was welcome and a gentle distribution to soften up the ground but do not be lulled into a false sense of security until we get a whole lot more. Here it penetrated the lawn to a depth of about 1cm only. The immediate effect will be to encourage the explosion of fungal disease on all susceptible plants (tomatoes, cucurbits, clematis, roses and the like) and to cause a fresh flush of weeds. Be vigilant on both. If you don’t want to spray for fungal attack, and most gardeners won’t, reduce the infected foliage, make sure you have good air movement and hope for dry weather. Obviously, avoid any overhead watering.
• Citrus trees are due for their spray of copper and summer oil. This spray will deal to mites and discourage botrytis. If you live in warmer coastal areas with reasonable shelter, we strongly recommend planting orange trees. They are by far the most productive fruit trees we grow here and keep us well stocked with oranges for twelve months of the year (although navel oranges and tangelos have a shorter fruiting season and do not hang on to their fruit until you are ready for it).
• If you have thrip infested rhododendrons (which shows up as silver leaves), now is the time to spray again if you plan to. You need to use a systemic insecticide which the plant absorbs and disperses, rather than a contact insecticide which only kills where it touches. Your local garden centre should be able to advise on suitable sprays. If the plants are badly infested, it weakens them as well as looking unsightly, so if you don’t plan to spray them at all, remove these plants and replace in autumn with better selections. The cold climate rhodos (which usually includes the American and German hybrids) are particularly vulnerable.
• Watch out for aphids and white butterflies, especially on brassicas. There are organic insecticides for brassicas or you could try a chilli spray. We haven’t tried it ourselves but a recommended home spray combines hot chilli sauce (tabasco or similar) at 3-5ml per litre of water plus 3-5ml of dishwashing detergent. A level standard teaspoon is 5ml but be stingy not generous as this is the maximum dose. This is a repellent, not a killer spray so you may have to combine it with digital control (squashing between fingers) and repeat fortnightly. If you don’t want to spray at all, draping net curtains or fine net cloth keeps white butterflies at bay.
• As space is created in the garden by digging potatoes or summer crops finishing, replant with winter brassicas, lettuce, or leeks for a late crop.