Healthy Kids

How to plant seeds in punnets and trays

Learn the right planting technique and watch your seeds grow.

Written by Stephanie Alexander Kitchen Garden Foundation
Young pumpkin sprouts in the peat pots on wooden background. Seedling.

Seed planting is an important activity, as it allows for a constant supply of new plants for the garden for minimal cost. It is much cheaper to plant seeds than to buy seedlings or larger plants, and in many cases means you end up with a really abundant crop.

Seeds are usually sown in one of two ways – direct sown into the ground where they are to grow, or sown into trays or punnets for transplanting into the garden beds at a later date. This activity refers to seeds that need to be planted into seed trays or punnets, for growing in the shadehouse or greenhouse.

Sometimes seeds are infertile. This can happen if they are old or have been stored incorrectly, or if they have been gathered from certain types of plants. (Look up F1 hybrids.) Check the age of your seeds before you go to the effort of planting them and don’t use any that are out of date.

It is always very important to read the seed packet carefully as it will tell you all the information you need to know. Check:

  • What the name of the plant is
  • What time of year you should be planting
  • That your seeds shouldn’t be sown straight into the ground
  • Whether the seeds should be covered with soil (do not need light to germinate) or not (do need light to germinate)
  • How far apart you should plant the seeds
  • How deep you should plant the seeds

Depending on the type of seeds you are planting you will need to choose which items you require from the following list:


What to do

    1. Choose and prepare your container. Wearing your gloves and using the trowel, fill the container with dampened seed-raising mix, as per the manufacturer’s health and safety instructions. Check whether children are allowed to do this or if only adults should do this. Be very careful when working with potting soil, and always follow the instructions.

    2.  Slightly press down on the top of the soil with your gloved hand. Not too hard! You want the soil to be firm, but not too compacted.

    3. Broadcasting sowing: You will need to broadcast sow fine seeds like basil, i.e. gently and evenly spread the seeds over the soil with your hand. They will be too small for you to place them individually in the soil, and you will need to use a larger container like a seed tray with a good surface area. Sow to the recommended rate per square meter. Check whether the seeds need to be covered – if they do, use the drum sieve or your hands to gently scatter a fine layer of soil over the seeds.

    4. Sowing: Larger seeds like peas or broad beans can be sown individually. These plants often lend themselves well to individual peat pots or punnets. Using your dibber, poke a hole to the correct depth in the soil, drop in your seed and gently backfill with soil with your gloved hand or a trowel.

    5. Put a clearly marked, waterproof label into the container, which states both the name of the plant and the date you planted it. Make sure you use a waterproof pen – otherwise the writing will wash away when you water the plants.

    6. Gently water your seeds in with a watering can, using the finest spray watering can rose. Water gushing onto the seeds can often disrupt or dislodge them, leading to no or reduced levels of germination.

    7. Place on potting benches in your shadehouse (hot climates) or greenhouse (temperate to cool climates).

    8. Keep an eye on your seeds – many need to be kept moist for the first few days or weeks to ensure germination. Watch for the first sign of growth, then the first true leaves, and chart the progress of your seedlings!

Written by Stephanie Alexander Kitchen Garden Foundation

The Stephanie Alexander Kitchen Garden Foundation is a not-for-profit charity whose vision is to see children form positive food habits for life. The Foundation provides the inspiration, information, professional development and support for educational institutions to deliver pleasurable food education, in conjunction with educators, partners and the wider community.

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