Unwins Seeds

Sow Seed Indoors

11 March 2014 | Posted in Gardening by The Unwins Family

Sow indoors.

While there is still a risk of frost many vegetable and flower seeds are more successful when they are sown indoors. Growing flowers from seed lets you choose the colour and variety you want in the quantities you need.  If you only want 20 plants it’s easy to sow that amount.

Sowing seeds thinly and being realistic about how much to grow are keys to success.  It’s very easy to get carried away and end up with hundreds of seedlings of one variety with all the resultant pricking out when twenty plants would do.

If you don’t have a heated greenhouse, use a windowsill propagator to give seedlings a frost free environment.  Get the propagator ready for any seeds that need extra warmth to help them germinate.  

Some annuals such as climbing Cobea scandens and ipomoea, and bedding plants such as antirrhinum, lobelia and nicotiana, generally take a while to get going from seed. They need a temperature of around 18-20C (64-68F) so sowing them early lets you get a head start.

It can also free up space in the propagator or n the greenhouse later on because some of these plants such as antirrhinum can be grown on at cooler temperatures once they have germinated; leaving space for the really tender annuals to grow on in warmth.

Growing herbs and vegetables from seed is a cost effective way of enjoying home grown produce and filling your veg plot whether it’s a large space or a small raised bed or container.

Prepare your seed trays 

Use a good quality multipurpose or seed compost to fill pots and trays. These composts are low in nutrients because seedlings don’t need much food. And they’re generally a finer grade than loam based composts to allow the roots of young seedlings to grow easily.

Fill pots and seed trays almost to the top with good quality seed compost or multi purpose compost. Make sure the compost fills right to the corners but don’t compress it too much, seeds need a snug blanket, not a straitjacket! Level the compost and tap the trays gently to settle the compost and to get rid of any air pockets.

To germinate well seeds need  sowing into moist compost; either water the compost once the seed is sown or, if the seed is fine and easily dislodged, just stand the pots or seed trays into a tray of shallow water and let the compost take up water from the base. It will turn darker as it gets damp.


Sow seed thinly and evenly over the surface of the compost.  Follow instructions on the seed packet regarding sowing depth and temperature. 

As a general rule fine seed such as antirrhinum should just be pressed onto the surface of the soil, if necessary cover the seeds very lightly with sifted soil or vermiculite.

Larger seed such as sweet peas and broad beans can be buried deeper, around twice their depth.

Most seeds need light to help them germinate, but some seeds such as pansies and violas germinate better when light is excluded. If this is the case it will be indicated in the sowing instructions on the seed packet.  The old and well tried method was to shade them with glass and a sheet newspaper, this still works well or use a lightweight black plastic tray from a supermarket fruit punnet to cover smaller pots and seed trays.

Once seeds are sown keep compost warm and moist but not wet until seedlings appear, which can take anything from 7 days to several weeks. 

Shade seedlings from harsh sunlight and turn trays regularly to avoid seedlings getting drawn towards the light. This can make them leggy and 'stretched'.

Check seedlings in propagators regularly to make sure they are healthy and growing well.

If you're sowing in seed trays rather than individual cells, seedlings are ready to prick out when they have two true leaves (in addition to the embryo seed leaves that emerge first  known as cotyledon leaves).


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