Why you should be planting your crops in autumn | Gardening 101 | Gardening Australia

In Hobart’s cool climate, Hannah has to get the timing just right for planting crops, but autumn is the perfect blend of light and warmth to get crops started for a good supply of food over winter and into spring. Subscribe 🔔 http://ab.co/GA-subscribe

Brassicas are already growing but to keep them coming over winter, Hannah plants a succession of seedlings from mid summer to autumn.

They are heavy feeders, so Hannah prepares the soil with lots of manure and compost and she will top up with liquid feeds every fortnight until the winter cold sets in. After this the plants slow down and won’t be metabolising the extra nutrients, but it can be restarted in spring.

Don’t plant brassicas in the same spot year after year, as brassica-loving pests and diseases can build up in the soil.

Hannah plants Chinese cabbage seedlings about 30-50cm apart to give them room to spread while allowing good airflow and reducing the risk of disease.

However, she squeezes in a quick-growing crop of pak choy in the gaps between; these will be harvested and gone before the slower-growing cabbages need that space. Always water in seedlings immediately after planting.

In a cool climate, don’t mulch the soil over winter; leave the soil exposed to get as much winter sun and warmth as possible.

Peas can be planted now too. They will need soil prepared with compost and manure as well, but also something to grow up. Hannah has found some trellis at her local tip shop that will work well.

Hannah plants thickly knowing she can thin out seedlings later to around 15cm apart; good airflow helps avoid problems with rust fungal diseases. These plants will be ready to flower and be pollinated as soon as spring hits. If you get heavy frosts then it may be better to wait to plant in early spring and/or start in a cold frame/greenhouse.

She plants some seedlings of quick-growing lettuces in the space between the trellises.

Potatoes are usually planted in spring in Tasmania, but Hannah’s garden gets lots of sunshine and only light frosts, so she is planting potatoes now.

Potatoes can be determinate or indeterminate, just like tomatoes. Indeterminates grow on a vine and these are the ones that benefit from having the soil mounded up as they grow, to produce more potatoes along the stem.

Determinate spuds, such as Kennebec that Hannah is planting, only grow in a single layer, so you don’t need to mount up the soil.

To speed up the growing process, allow your seed potatoes to sprout before planting – called chitting – as this gives them a good head start, so they’re already to get growing when they’re put in the soil.

It’s important to use verified seed potatoes, as these are guaranteed disease free.

Green manure:
Green manure is great in beds that are a bit tired from previous crops.

Hannah plants a bed with a green manure mix of oat and rye grass, mustard and pea seeds. The crop stop weeds taking over, keeps the soil in good condition, and provide habitat for useful microbes. It can also help avoid soil compaction from excess rain and can add nitrogen to the soil.

In 4-6 weeks, slash the plants down by hand, a hoe or even a mower and mix it back into the soil. Make sure to do this before flowering as this uses up a lot of the energy and nutrients we want back in the soil. Leave to decompose for another few weeks before planting the next vegie crop. 

Garlic:
Autumn is a good time to plant garlic in cool climates, before the soil loses its warmth.

Hannah plants three rows in well-drained soil about 30cm apart, with individual garlic cloves spaced about a fist’s width apart. She’s chosen ‘Tassie Purple’, which thrives in the cool climate. Make sure the flat side is planted down and the pointy end faces up! Water in well.

Filmed in Hobart, Tas.

Featured plants:
Chinese cabbage (Brassica rapa cv.)
Pak choy (Brassica rapa cv.)
Pea (Lathyrus oleraceus cv.)
Lettuce (Lactuca sativa cv.)
Potato ‘Kennebec’ (Solanum tuberosum cv.)
Broad bean (Vicia faba cv.)
Garlic ‘Tassies purple’ (Allium sativum cv.)
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