Growing Wildflowers from Seed

The value of wildflowers in the garden, especially from the point of view of attracting wildlife, is something that has never been in dispute.  Our native plants are guaranteed to bring in bees, moths and butterflies and much more besides if they are planted in appropriate places in even the smallest garden.  How best to grow wildflowers from seed however is something that can cause problems for even the most proficient gardener.  Why should this be?  We expect these plants to seed and grow naturally and easily in their native habitat, but they don’t always behave as we expect them to when we try raising them ourselves. Seeds of all species, whether native or not, have built in strategies to ensure survival.  All too often we are used to sowing hardy perennials or annuals that may have been selectively bred to ‘remove’ some of these germination requirements to make germination easier.  In the case of our own wildflowers, all these survival strategies are still in place.  We need to know a little about these plants and how they grow to crack the ‘germination code’.

February is a particularly good month to sow seeds of some wildflowers.  Perhaps not the month we would naturally start our seed sowing, but many seeds require a period of very cold weather before germination will take place.  This is known as ‘vernalisation’ and species requiring this cold treatment can be sown now, as February is often our coldest month.  We are sometimes advised to put seeds of the wild Primulas (cowslip, primrose and oxlip) or those of snakeshead fritillary, wild hellebore or poppy into the fridge or freezer for a while before sowing.  Unfortunately this often does often not reproduce the exact conditions these species need – several spells of really cold temperatures interspersed with fluctuating higher ones.  There is really only one way of exposing seeds to these exacting conditions and that is to sow in pots or seed trays and leave them outside in very cold weather.  Nature will do the rest for you very efficiently.

Vernalisation is a mechanism by which the plant protects its offspring.  For many species, germination in the mild damp conditions of autumn could spell disaster for those plants which are unable to survive their first winter as tiny seedlings.  There are plenty of autumn germinators of course, but their seedlings are adapted to cold winter weather.  If germination is stimulated by fluctuating temperatures, several cold snaps eventually followed by some mild warm weather will generally indicate that spring has arrived – just the right time to send out those new young leaves.

Reproducing natural circumstances can give us an insight into just what conditions wildflower seeds need to germinate.  Many, including the wild vetches, trefoils and cranesbills, germinate more easily if they are ‘scarified’.  This involves gently rubbing the seeds between two pieces of sandpaper which begins to break down the seed coat.  This action allows water to freely enter the seeds and germination can begin.  In natural conditions this breakdown will happen slowly over months or even years as the seed moves around rubbing against particles of soil or small stones.

Light is another very important factor in the germination of some wildflower seeds, especially many annuals.  Poppies in particular are programmed to germinate after exposure to light.  Poppies were originally plants of barren soils and scree slopes, bursting into life after disturbance by animals or soil slips.  In the more recent past, this disturbance happened when the plough turned the soil in springtime, and the buried seeds of corn poppies came to the surface.  It still happens today, and accounts for the sudden appearance of swathes of poppies where work is carried out to build new roads or houses and the soil has been disturbed. 

In the garden, these conditions can be easily reproduced by not covering the seeds after sowing.  Where annuals such as poppies and corn marigolds are to be grown, simply scatter them on the soil surface and gently press them into the soil with hands or boots.  This ensures they have made good contact with the soil, but are still exposed to the light they need.  Other wildflowers benefit from this treatment simply because the seeds are so small.  Wild marjoram, the wild campanulas such as harebell and clustered bellflower, and foxgloves have minute seeds that can easily be covered too deeply in open soil or in seed trays.

Yet more plants require very wet conditions in order to grow from seed.  These, as you would expect, are wildflowers you might find along river banks or on pond sides, including meadowsweet, marsh marigold, yellow flag and devil’s bit scabious.  Where these are sown in pots or trays, they need to stand in deep saucers that are permanently full of water, to reproduce the conditions in which they grow in the wild.

Looking at the places that our wildflowers naturally grow can give us insights into how to germinate their seeds, but we still need to apply basic sowing techniques in order to get good germination results.  Annuals and biennials can easily be sown into bare soil in the garden in spring or autumn and produce a fine display, but perennials are always more successfully grown if they are started in seed trays or pots.  The seeds of some perennials will germinate where they are to flower in borders, but scattering seed onto grass virtually never works.  Treat your wildflowers as you would any precious garden perennial and you will have more than enough plants for your own garden and to supply friends too. 

Use a soil based peat free compost if you can find one.  If not, you may want to use your own garden soil with a little home made compost added, although bear in mind you will get a few unwanted weed seedlings which might be confusing.  Fill a small pot or tray and firm the compost lightly.  After scarifying your seed (if this treatment is required) scatter it lightly on the surface of the compost.  Then, very lightly cover the seed with horticultural grit.  This will not swamp the seeds, and will help to prevent problems with fungal diseases.  Water lightly and after labelling put the pot outside in a safe spot.  If you are germinating plants for damp conditions, stand the pot in a deep saucer of water and ensure that it is topped up regularly.  If the seed is very small, sow it on top of the grit, rather than covering it.  This allows the tiny seeds to settle between the grit particles, but they are not lost under a thick layer of compost.

Once established, many wildflowers will self seed and add something very special to your garden, and getting them started from seed, especially more unusual species that may not be widely available as plants, is very satisfying.  They can provide almost year round colour and interest as well as bringing more wildlife to your garden.

© Text and photographs Jenny Steel 2017