How to succeed with your seeds
Here’s the Juliana guide to successful seed sowing
The best medium in which to sow your seeds is a specially blended seed compost, as this will provide the perfect conditions for germination. Seeds need free-draining conditions – they won’t like sitting in damp soil or compost, which can lead to the seeds rotting – and they don’t need nutrients in order to germinate as there’s sufficient food within the seed for germination to occur. If you’ve ever wondered why seeds germinate so well in gravel paths, it’s because they provide the perfect conditions.
You can also use a good quality peat-free, multipurpose compost but some seeds might not like the added nutrients.
Don’t use garden soil as it’ll be full of weed seeds and when they germinate you won’t be able to tell the difference between the weed seeds and the seeds you sowed.
You can use pretty much anything as long as the vessel has drainage holes, or they can be easily added. You can make pots from newspaper with the help of a wooden pot maker, and you can recycle yoghurt pots and plastic food trays – some of these containers, which come with fruit or vegetables in them from the supermarket, also have a clear plastic lid which can be used as a mini greenhouse.
Garden centres and online stores have plenty of choice from module trays and individual pots to jiffy pellets and coir pots. Gardeners are increasingly interested in using less plastic and the good news is there are a growing number of products that are made from sustainable and biodegradable materials such as bamboo.
It’s important to wash pots and trays thoroughly in hot, soapy water before you use them so that fungal diseases don’t spread.
Remember that information about when to sow can be found on the seed packets.
Photo: Grøn Kommunikation.
Read the Seed Packet
Check the various seed packets for details of when and how to sow, as some seeds have specific requirements. For instance, some seeds need to be buried in the soil, but others need light in order to germinate, so these need to be left uncovered on the surface of the compost. Some seeds are so tiny they’re tricky to distribute on the compost, but mixing them with silver sand can help to scatter them evenly. It’s best to sow thinly as densely sown seeds will compete for light and water and crowd each other out. Large seeds should be sown two to a pot; if both seeds germinate the weaker of the two can be removed and discarded or repotted on its own.
After sowing and watering the pots it’s important to make sure the compost doesn’t dry out otherwise the seeds won’t sprout. The easiest way to do this is to cover the pots and trays with either plastic lids or clear food bags to create a humid environment. Remove these covers every day for 10–15 minutes to provide some ventilation and wipe down the covers to remove excess moisture. Both these measures will help to prevent fungal diseases taking hold.
It generally takes 7–14 days for seeds to sprout and at this point you can remove the covers.
See the Light
Providing sufficient light, particularly in late winter and early spring can be the biggest problem. Not enough light will lead to weak, spindly seedlings straining towards the light. It’s possible to provide artificial light using special LED grow lights – these will provide the right type of light unlike typical household light bulbs. If you’d prefer a quick trick for boosting light for just a few seed trays, try using sheets of stiff white card and prop these up behind the trays and pots so that they reflect light back onto the seedlings – it’s surprising how big a difference this can make!
Om Lars Lund
Danish horticulturist and journalist
Lars Lund has for many years engaged in the garden and greenhouse. Lars has published many books about greenhouses, and he has participated in many Danish horticultural TV shows. He is a walking garden encyclopaedia, and he has answers for most basic cultivation questions – also the more ambitious ones.