Monty Don reveals the common potting mistake we're all making – and what we should be doing instead

Green-fingered icon Monty Don has shaped our plant habits through his years of ingenious tips and tricks – covering all floricultural practices for amateur and professional gardeners alike. From weed removal tips to advice on growing vegetables, Monty has influenced gardens on both sides of the Atlantic; but his latest advice may just be his most valuable yet. 

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Gardeners of all abilities are likely to have 'potted up' a plant – the seemingly simple act of transporting seedlings into a larger container. However, this initially easy task is not quite as simple as it first seems. In a video for TogetherTV, Monty Don revealed the common potting mistakes we're all guilty of making and demonstrated his new method that will save us a lot of compost. 

Monty Don's common potting mistake 

The success of a pot depends on the plant's strength, so it is essential to make sure your root is as healthy as possible throughout the pre-potting stage. Before saving compost in the potting stage, Monty suggests using more in the seeding process to create a longer root run. 

'It's a false economy not to fill seed trays up with compost. The more compost you have in there, the longer the root run can be, and the healthier they'll grow,' he shares. 

'What I do is fill right to the brim, and then I just wipe the excess off,' Monty adds.

See: Monty Don's beautiful Longmeadow garden in Herefordshire 

While Monty's post-potting tip has already exposed one common misconception, Monty shares that the most significant mistake occurs when choosing the correct sized pot.

'Ideally, in a pot, you just have [around] a centimeter of fresh compost for it to grow into. Don't be tempted to get the biggest pot you've got and think [your plants] will grow enormous. It won't do it any good at all, and it's a complete waste of compost,' he announces.

Do other gardening experts agree?

Before we change our potting habits entirely, we sought advice from the people at the top of the compost world. But do they agree with the beloved British gardener?

Building on Monty's pre-pot seeding tip, Kate Turner, Gardening Guru at Miracle-Gro, also urges us to ensure we use enough compost to encourage the seed to grow. 

"I would add to Monty's advice that you need to fill them up because the seeds, once they emerge, are always looking for light. If there is too much black plastic in the way, they will struggle to grow,' Kate shares. 

Kate then reinforced the importance of choosing an appropriately sized pot and similarly warned us against an unnecessarily large pot. 

'When 'potting on' from a seed tray or from one pot up to a bigger one, just go up one size. If it's too big, then the seedling won't send its roots out and will sulk and potentially rot as you will water for the bigger pot, but the roots won't have grown out. With seedlings from seed trays, small jiffy pots are ideal or a pot no bigger than 7cm,' Kate explains. 

'When sowing larger seeds such as courgettes and pumpkins, don't sow in a seed tray but in a pot that is between 7-9cm to encourage the roots to grow out and then once the roots fill the pot, transplant into a 10-12cm pot,' she adds. 

See: Monty Don’s tips on getting the perfect lawn – and the mistakes you're making

Thanks to Monty and Kate, we'll certainly avoid making the same mistake again.