Gardening: Cool season success

By Meg Liptrot

Meg Liptrot has tips to help warm up your kitchen garden

Greenhouses, DIY grow houses and cold frames boost year-round vegetable garden productivity, and are a big help in winter. Photo / Doug Sherring
Greenhouses, DIY grow houses and cold frames boost year-round vegetable garden productivity, and are a big help in winter. Photo / Doug Sherring

The obvious growing seasons for home gardeners are spring and summer, but autumn and winter are great for growing if you employ a few tricks. First, plant and sow vegetables that are clearly labelled as suitable for the season. Check the zone and sowing time on the seed packets.

Although some state late summer sowing times, you can challenge that to a degree. Generally, the label refers to direct sowing in the ground. If you change the growing conditions, and sow in a warm spot, or in a pot, you will likely have success.

Choose the sunniest, best drained spot in your garden, ideally in a raised bed. Grow veges on the north side of a masonry wall, which will store and radiate heat, or sow seed under a cloche or larger growing tunnel if you have space.

A growing tunnel or small glasshouse are cost effective options to ensure you can harvest veges right through the year, and get seedlings started in early spring to get a jump on your summer garden. A glasshouse is also a pleasant place to potter in on a rainy day.

Glasshouses are attractive additions to backyards if there's room. Vintage cold frames, cloches, glasshouses and growing frames ooze old-world charm. For inspiration, check out some of the English and American websites offering these wares. In this part of the world, the closest we can get to this look without breaking the bank is by integrating recycled timber or steel crate windows into a DIY design.

There are good-looking locally made options, but these tend to be of pragmatic rather than decorative design. Commercial glasshouse manufacturers offer models in toughened glass or polycarbonate material, with frames usually of easy-care aluminium.

It is relatively easy to build a simple DIY grow house. Attach thick polythene to a timber frame with gaffer tape and staples. Ensure you allow for ventilation by opening the doors or rolling up the sides on hot days. For a more permanent structure, use recycled windows or French doors with small panes. For safety, tape clear gaffer tape or safety film across the pane in case of breakages.

I've previously used timber-framed windows for a cold frame. Eventually, the glass was broken by an errant tennis ball. Ensure you install latches to prevent breakages in wind gusts. Replace broken glass (use gloves, and wrap carefully) with tough pieces of polycarbonate, or thick polythene, which is available in lengths cut to measure at hardware stores or in bulk from greenhouse manufacturers.

Avoid using opaque film in a spot that doesn't get full sun all day in winter. Days are shorter and there is less available light, so there's no need to reduce light further. Opaque greenhouses are mainly for seedling propagation. Plants grown to maturity in an opaque house may end up leggy, particularly in winter.

Choose clear plastic for winter crops, and ensure there is daytime ventilation to prevent plants overheating. Wean hardier types out of the cloche once they are established, but ensure they are sheltered from cold wind.

To warm things up without a cloche or glasshouse you can modify the soil by keeping it aerated. Cold, heavy soil is less than ideal for sowing seed. Dig a trench and introduce lighter soil from another spot in the garden, then sow or plant, or add a few inches of organic seed-raising mix to the trench. I do this when sowing delicate seed such as carrot.

Protect new plants and seedlings from wind chill - erect a small wind break if need be. This will ensure you've given your seedlings a good start in life, for a productive cool-season garden.

Winter kitchen garden

• Plant Chinese greens, mizuna, broccoli, kale, cabbage, and cauliflower. Plant leafy greens such as perpetual spinach, endive, chicory, silver beet. Sow rocket, corn salad, winter mesclun salad, and miner's lettuce. Plant hardy herbs such as coriander, Italian parsley and chives.

• Peas and broad beans are easy to grow. Peas need around 1.5m of chicken wire to hook their tendrils into as they climb. Cover with bird net and sprinkle pet-friendly Quash snail bait around your plants.

• Seed garlic is at garden centres now. Or, buy cheap organic garlic that has already begun sprouting from the grocer. Non-organic garlic is usually sprayed to prevent sprouting. Plant leek and onion seedlings. Sow carrot and beetroot (in rotation after heavy-feeding brassicas) in a well-drained, sunny spot for spring/early summer harvest. Soak beetroot seed overnight before sowing.

• Divide strawberry plants and plant now for a healthy harvest later in the year.

• Before sowing or planting, incorporate organic fertilisers such as well rotted manure/sheep pellets, lime or dolomite and basalt rock dust (found in Environmental Fertiliser's Nature's Organic Fertiliser, or Agrissential's Rok Solid).

• Seaweed is plentiful this time of year on the east coast, washed up in great piles after storms and it makes a great addition chopped into the soil.

Keep warm

Suppliers of NZ-made glass and greenhouses: trulux.co.nz (G); edenlite.co.nz (G/PC) and glass-greenhouse.co.nz (includes lean-tos for small spaces); hunkin.co.nz (PC), wintergardenz.co.nz (PC)

Cloche and tunnel house suppliers: morrifield.com (PF, PC), redpath.co.nz (G, PC, PF) (Redpath also supply a range of greenhouse plastic films.)

Breaking new frontiers: The solar Geodesic Dome Greenhouse domegrown.net.nz (PF)

KEY: (G) toughened glass (PC) polycarbonate (PF) plastic film

- Herald on Sunday

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