7 essential tips to help you grow your own seedlings like a gardening expert

A pair of hands holding a small green seedling plucked from soil while other seedlings are growing in a black tray below

Got a green thumb but don’t know where to begin? Market gardening whānau Pakaraka Permaculture share their seedling-growing tips.

It’s simple to grow your own seedlings, and you don’t need a fancy set-up – any sunny benchtop, a bit of floor space in your home, or an outdoor bench can do the trick. Starting plants from seeds allows you to grow them in a protected environment and gives you a head start of several weeks before conditions are ready in the garden.

1. Trays and pots

Be generous with the size of the cells you are using and the spacing in between your seedlings. You can use open trays or containers without dividers, or you can use pre-divided trays, commonly referred to as cell trays. Even small punnets, toilet roll tubes and egg cartons can be used for propagation if you grow a relatively small number of seedlings.

Niva Kay and daughter planing seedlings in small black pots

2. Sowing tips

Use a premium potting mix and keep it dry and in the shade until it needs to be used (wear a face mask when handling it to minimise the risk of contracting Legionnaires’ disease, a type of pneumonia caused by exposure to a bacterium known as Legionella). Fill your tray with potting mix, tap it a couple of times on the bench to let it settle, then top up with more potting mix so it is full to the brim. If the quality of the seeds is good and the seedlings are going to stay in their container for up to six weeks, sow each seed at the spacing you want it to be at planting time. When sowing seeds, it is always a good idea to label each tray or row with the name of the seed.

When the germination of the seeds is below 80%, we suggest using a different technique. You can sow two seeds in the same cell, and if both germinate you can either thin out the weakest one or keep both of them and separate them at planting time into two transplants. Placing the seeds about 1cm apart will make it easier to separate them if you chose to do so.

Another option is to sow the seeds close together, about 0.5cm apart, in a group that will later be moved to another tray at a larger spacing, a practice known as pricking out. This allows you to choose the best plants to continue growing. Pricking out the little seedlings at the cotyledon stage – before the plants develop their first set of true leaves – will lead to a better root structure. When handling little seedlings, never hold them by their delicate stems as it will often stunt them or even kill them. Instead, handle plants by holding their leaves or roots.

3. Caring for your seedlings

Air circulation, ventilation and light are key factors in creating a healthy plant environment. The soil needs to be moist but not soggy to prevent it from being waterlogged, anaerobic and developing fungal diseases. Keep the growing environment sunny and keep the trays well watered, by gentle watering from above with a hose, watering can or a sprayer. The trays should never dry out, especially at the germination stage.

Overhead view of a grey plastic tray holding multiple little pots with growing green seedlings

4. Hardening off

Exposing the plants to the garden conditions several days before transplanting is called “hardening off”. Plants prefer gradual change, so taking the plants outside will help them get used to the wind and sun before transplanting. It’s better to take plants outside for the first time when the day is overcast, or in the evening, rather than on a stormy or very sunny day. However, if you are planting under the protection of a cloche, there is no need for hardening off.

5. When are the plants ready to go into the garden?

If the roots easily separate from the potting mix, it’s better to leave them in the tray to harden off for a few more days. The potting mix should be held by a healthy root system that is not too bound and hard. It is best to plant the seedlings with as much root mass and potting mix as your plant has in its container, in order not to disturb the root system.

6. Planting time

The decision about when to plant them in the garden depends on how well you can take care of them, how close they are to overgrowing their container, and when the conditions are optimal. Planting on a cloudy or drizzly day helps prevent plants from drying out and reduces their stress. Otherwise, plant early in the morning or, even better, late in the afternoon. Make sure to transplant into a well-hydrated bed and gently water the plants soon after planting. To transplant, move the soil to the side with your hand or a trowel, insert the plant at the correct depth, and fill in the gap. It’s that easy!

7. After planting

The best indication of successful planting is seeing new leaf growth within a few days after transplanting. This means that the transition from tray to garden went smoothly. If new leaf growth doesn’t happen quickly, don’t despair – it’s a learning opportunity. The plant’s health might not be optimal, but it can still be a healthy and productive plant.

Edibles you can sow right now

  • Artichokes
  • Endive
  • Broad beans
  • Beetroot
  • Broccoli
  • Cabbages
  • Carrots (sow direct)
  • Cauliflower
  • Celery
  • Chard
  • Coriander
  • Kale
  • Kohlrabi
  • Leek
  • Lettuce
  • Onions
  • Rocket
  • Radishes (sow direct)

The Abundant Garden by Niva and Yotam Kay

Edited extract from The Abundant Garden by Niva and Yotam Kay of Pakaraka Permaculture (Allen & Unwin, RRP $45).

PHOTOS BY NIVA KAY AND JANE USSHER


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