2: Choosing containers and growing seedlings

Choosing containers
  • Key considerations when choosing containers are that they’re at least 400mm deep and have drainage holes in the bottom. Make sure you can manage the weight of the container and that’s it not too heavy for your site eg balcony. Containers that are urn-shaped with a small opening aren’t suitable for fruit trees as the roots grow into the belly of the container and you can’t get the tree out to root prune it.
  • At our 3 sites the containers we’re using are made out of heat-treated pallets. There are no chemicals in them but we line them with black plastic anyway to assist with longevity and to contain the potting mix. The gaps between the slats at the bottom of the container are quite wide, so we staple down some plastic wire first to hold the black plastic in place. Fold the black plastic over at the top to make it neater. Cut slits in the bottom so excess water can run out.
  • It’s important to fill your container with potting mix, not compost and not soil from the garden. Potting mix has pumice and coconut fibre added to it which is essential for good drainage and water retention.
  • Some of our containers are 600mm deep so we’re filling them up halfway with used potting mix from a nursery which will be nutrient deficient so on top of that we add a generous amount of sheep pellets. Then on goes good quality potting mix for the top half.
  • The other containers we’re using are grow bags which come with holes in them, filled as above. Don’t buy cheap ones as they’re heavy when filled and when you move them about, cheap ones can fall apart.
  • We’re also using flexi buckets which are a good shape. We drill 15mm holes in the bottom of these ones as there are ridges which keep the bucket up off the ground. If you use a flexi bucket that doesn’t have ridges, drill the holes in the sides close to the bottom of the bucket.
  • We don’t sieve the potting mix that fills the containers as seedlings can handle a chunkier mix than seeds. If you’re using a cheaper potting mix, you may need to add some blood and bone or our general fertiliser (rock dust) to the potting mix, especially for the fruiting plants which will be in their pots for a while.
  • Use a knife to cut down the rows of seedlings and gently work them out of the soil, disturbing their roots as little as possible. It’s good to have the punnet a bit dry at this stage – it makes them easier to prick out.
  • Leafy greens will take another couple of weeks before they’re ready to plant out. Fruiting plants will take around 4 weeks from this stage until planting out.
Planting peas
  • Climbing peas need a framework. We’ve made one out of bamboo stakes that we’ve criss-crossed. Peas don’t need any extra fertilisers when planting.
Sowing root crops
  • Root crops (with the exception of beetroot) don’t like root disturbance, so we sow them directly into the grow bags. Grow bags are good for root crops as they can take over the whole bag and not get disturbed.
  • Gently sprinkle a fine layer of potting mix over the seeds and then apply a light covering of potting mix over the top and water in.
Growing potatoes
  • Roll down the sides of a grow bag and fill a third with potting mix. Place potatoes in – not too close. Apply a handful of neem granules to ward off psyllids, a layer of potting mix just to cover them and handful of our balanced fertiliser (rock dust) and water in.
Planting fruit trees
  • Citrus are the best fruit trees to grow in containers. We’re putting mandarins and lemons in our 3 sites in grow bags.
  • We mix a handful of balanced fertiliser (rock dust) into the bag and mix it in. This will help develop a good strong root system. Water in.


Camera: Davian Lorson
Editor: Michael Hardcastle