Hardening Off in a Propagator

The Vitopod Heated Propagator is ideal for overwinteringOnce your plants have made it through winter, the time will come when they must leave the safety of their heated propagators and moved to their final growing place .

Before moving plants out of your heated propagator, you will need to harden them off. “Hardening off” is the process of acclimatising your plants to live outside of a heated environment, encouraging them to develop stronger, waxier leaves that can cope with natural conditions outside the propagator. This must be carried out gradually to avoid your plants going into shock.

You can start hardening off your plants when night time temperatures reach 5°C; although the higher the temperature, the easier the process will be. If hardening off at 5°C, you still need to implement some additional protection such as a frost protection fleece. A frost protection gardening fleece will keep the plant safe from any sudden drops in temperature and will allow you to plant outside sooner.

A seedlings true leaves just coming through

The decision for when to harden off plants should be based on the time of sowing/planting rather than the development stage of your plant. Young plants are less likely to tolerate sudden changes in temperature, so these should be left a little longer. Typically, when your plant has developed its true leaves it will be ready for hardening off.

Plants grown in warmer environments, such as an Electric Heated Propagator, will need to be hardened off more gradually, as these are used to higher temperatures.

The duration of the hardening off process can vary depending on what you are growing. However this is the typical process for hardening off in an electric heated propagator:

Stage 1: Leave the lid off your propagator during the day

Recommended Duration: 7 days

Stage 2: Leave the lid off your propagator all the time

Recommended Duration: 7 days

Stage 3: Remove plants from the propagator (ideally move to greenhouse or mini greenhouse, or outside with plant frost protection)

Recommended Duration: 7 days

Stage 4: Transplant your plants in their final planter

A Quadgrow planter makes a great final home for your seedlings

In addition to these steps, it is important to consider the other changes that your plant will have to adapt to and how you can prepare them for this.

- Your plants will be experiencing greater levels of direct sunlight, so try to move your plant to a sunnier spot gradually throughout this process to lessen the shock.

- Aim to plant out on an overcast day as this will minimise the risk of your plants wilting.

- If planting outdoors, protect young plants from slugs with some organic slug pellets and keep hungry pests away.

- Produce 2x larger yields by planting your plants into a Plant Guardian Planter. These will keep your plants perfectly watered for up to 2 weeks at a time!

Now your plants will be ready to grow and your Vitopod Propagator will be free for sowing your springtime seedlings!

If you have any questions about hardening off, or if you’d like to share any advice from your previous experience, feel free to call us on 0845 602 3774 or email us at info@greenhousesensation.co.uk. Our Gardening Angels are always happy to help!