Container growing in a Harvst mini greenhouse

The shelves in a Harvst mini-greenhouse are designed to take containers in which you can start seedlings, and also grow on to harvest. The frame is designed to fit larger tubs in the bottom, if you’re not putting your greenhouse directly on the soil. Here we’ll walk you through everything you need to know about growing in containers.

Seed trays or gravel trays

These sit on the top shelf of the Yard model, or on the wide shelf of the Terrace model. They are either filled with compost/soil, or you can put cells/modules into the tray.

The tray sits directly on the shelf bars, which are designed for 38 x 24 cm trays.

If you are using pots, you’ll need to put those pots into a gravel tray or strong seed tray which will in turn sit on the shelf bars.

Deep seed trays

Deep seed trays are the same length and width as standard seed trays (approx 38cm x 24cm), but will hold more soil; for plants such as salads, that can be grown all the way to harvesting without the need to transplant.

Deep seed trays will sit on any of the shelves in your Harvst greenhouse.


Large grow tubs

We recommend 600 x 400 mm stackable euro crates, which will fit snugly in the bottom of your Harvst mini greenhouse, and hold enough soil for plants which need more depth.  When full they contain around 40 litres of compost.

These will be heavy when filled with soil, so consider putting them into your greenhouse before you fill them.


If your Harvst greenhouse is sitting directly on concrete or brick, it will be cold in early spring and late autumn. We recommend a layer of insulating material between the ground and your lower growing containers; plywood or any other scraps of wood work well. Doing this will not only insulate but provide some much needed drainage too.

Heating your containers or grow tubs

Harvst low-voltage waterproof heaters are suitable for all kinds of growing containers. They plug directly into the mains-powered Harvst control units (not suitable for solar powered control units).

Up to 8 heaters can be fitted to a control unit. A heater can reach 40 degrees C, so it needs to be thermostatically controlled, using the sensors supplied with your smart control system. They are self adhesive and can be fitted inside or outside a container.

We recommend:

Zone 1 heaters

  • Heater pads in the bottom of your large containers at the bottom of the Harvst mini greenhouse. These will warm the soil and keep the general temperature of the greenhouse nice and cosy.
  • The black soil sensor should be placed in a grow tub, which will warm up faster than the larger tubs.

Zone 2

  • Our heated seed trays are ideal for the top level[s] of your greenhouse.
  • Make sure you put the upper zone temperature sensor in the soil of the tray that’s heated, so it controls the temperature and doesn’t get too hot. The small amount of soil in a seed tray will heat up quickly and your seedlings may wilt and die if they get too warm or too dry.