How to sow long-term root crops, hill up potatoes and chit kumara (sweet potato)

Sowing carrots and day-long onions
  • It’s important to prepare your soil well before sowing root crop seeds. It needs to be friable, have good drainage and be worked through to a depth of around 30 cms so that carrots don’t fork. A barrow load of compost forked into the soil will help create the right conditions to sow in. Rake it all smooth.
  • Today we’re sowing Kuroda Improved carrots and Purplette onions (smallish red onions). Carrot seeds need to be as fresh as possible. After purchasing them, put them in the fridge for at least two weeks before sowing. When the chilled seeds come out into the warmth, they’re stimulated to germinate.
  • Now’s the time to get your summer or day-long onions in. Day-long onions have white papery skin and don’t store like main crop day-short brown onions, but it’s great to have fresh onions in the summertime.
  • Make furrows with a hoe or your hand. Either pour the seeds into your hand and sprinkle them into the furrows or gently tap the packet held over the furrow. Sow the carrot seed quite thickly as their germination rate can be patchy. Then backfill the furrows with your hand and gently but firmly pat the soil down.
  • We sow onions in between the carrot rows. Onions and carrots are good companion plants – the smell of the onions keeps carrot fly away.
  • Next we apply rock dust which is a balanced fertiliser, but has a good dose of phosphorus which we need for root growth.
  • It’s important to keep weeds out of this bed. Carrots and onions don’t germinate quickly and they’re not very good at competing with weeds.
  • It’s also important to keep an even amount of moisture in the soil during the germination period. Sunny warm days followed by prolonged rain can work against even germination. We suggest you lay something on top of the seeds – a layer of newspaper or thin cardboard will do the job, but we choose a couple of old towels. Secure whatever you choose with something heavy like bricks. Water the bed well.
  • Keep your cover on for 7-14 days until the seedlings start popping through the soil.
Hilling up potatoes
  • Depending on how quickly your potatoes grow, you’ll need to hill them up every 2-5 days. The more the plants are buried, the greater bounty they’ll produce.
  • We’ve run out of soil from the bed itself, so we add some well-rotted compost to the central channel and then grub it from there out to each side to cover the plants. Don’t be concerned if it looks like you’re pushing the plants over – they’ll grow back through the soil.
  • If you’re growing potatoes in a container, make sure you keep it topped up with compost or more soil so the leaves are just above the soil level.
Chitting kumara
  • Kumara or sweet potatoes are a subtropical crop so you don’t want to plant them till December. Planted too early, they’ll just sulk in the soil.
  • With kumara we plant slips, which is the seedling that a kumara produces when the tuber is submerged in a tub of potting mix.
  • Fill a tub with a good organic potting mix to about 5 cms, lay the kumara tubers on the soil, then add another 10 cms of potting mix over the tubers. Gently water and set the tub in a warm, sunny position.
  • Seedlings (slips) will appear over a period of 7-14 days. When they get to about 10 cms long, hold the soil with one hand and gently pull the slip out – it’ll come away from the tuber with a root on it. You can either transplant the slip into a single pot to grow its roots on a bit more or plant straight out into the ground.
  • You’ll get 20-30 slips from one tuber. They’re a fantastically productive crop.


Camera: Davian Lorson
Editor: Thomas Asche