Succeeding with self-seeders

By June 18, 2018Articles

Tamsin Westhorpe celebrates self-seeders and offers advice on getting the best out of these generous plants

ETBT1G Foxgloves in a cottage garden. Path leading to hut.

Foxgloves are a typical cottage-garden plant that will self-seed prolifically

 

There’s so much to celebrate about footloose and fancy-free self-seeders. These plants are annuals, biennials or perennials that simply scatter copious amounts of seed. For this reason, they pop up everywhere and, once you’ve planted them, you find that you tend to have them forever.

Most gardeners are grateful to self-seeders for their ease. They produce free plants, and they position themselves in inventive places that can lead to an unexpected display. However, they are like mischievous children who do whatever they choose and on occasion must be controlled. Control is the key to having success with these plants. It’s up to you to edit out those that overstep the mark.

Many of these efficient plants have picked up a bad reputation for being invasive, but without them our gardens would be very contrived. A few self-seeders mixed with your better-behaved ornamentals will create full borders where plants merge and cushion each other in a natural way. It is these we must thank for the large drifts and swathes of natural planting that so many of us aspire to create.

Self-seeders should also be praised for their fundraising skills. It’s these plants that raise lots of money for charity as they are the ones that are plentiful enough to pot up and sell on for a good cause. As the old saying goes, ‘one man’s trash is another man’s treasure’.

 

Right plant, right place
If a self-seeder has germinated and formed a healthy plant, it is likely to have found the perfect place to thrive. This explains why, in some gardens, a plant will become very prominent and in others not so. When I gardened on a sandy soil in Dorset, Verbena bonariensis sprung up everywhere, but in my heavy clay border in Herefordshire I can’t get even one plant to survive.

My garden is made more enchanting thanks to self-seeders. Over the years the fritillaries have created enviable drifts near the pond and the giant Inula racemosa stands like a row of soldiers along the edge of my garden path. In this gravel path erynguims self-seed and I quickly whip them up and pot them on before they get trodden on.

Alchemilla mollis makes a home between gaps in the paving, and the species tulip, Tulipa sprengeri, is positively abundant after years of self-seeding. The self-seeder year in my plot starts In March with the biennial Smyrnium perfoliatum adding a vibrant lime-green to the borders, which is quickly followed by foxgloves and then aquilegia.

This early summer symphony all started with the purchase of three plants and cost me about £20, so what’s not to like about that?

 

Rooting power
When choosing to grow prevalent self-seeders it’s worth finding out how they root. Many are easy to lift and pull up, such as Nassella tenuissima, forget-me-nots, Leucanthemum vulgare (ox-eye daisies), primulas and hardy geraniums. All these have fairly shallow roots and can be easily removed, when young, from a border with a hand trowel.

It’s those with a tap root such as Inula racemosa and comfrey that are hard to lift and can become a nuisance. If you decide that you no longer want to share your garden with a particular self-seeder, be aware that the seed can sit in the soil for many years before germinating.

You might think you have weeded out the culprit, but don’t be surprised to see a few more plants to germinate the following year. On balance, I’m all for sharing the garden with self-seeders. All the best things in life are unplanned and unexpected, and these plants allow me to pick guilt-free bunches for my vases.

 

Five tips for success with self-seeders

• Research self-seeding plants before committing to them. Will they be easy to pull up and remove?
• If self-seeders are deep rooted and hard to remove from the garden, cut off the flowers before they have the chance to set seed.
• For those people who have steep banks and inaccessible areas of their garden where soil can’t be turned easily, self-seeders could be the answer. Some will grow in the most inhospitable places.
• Edit out self-seeders that are taking over – the ideal time to do this is in early spring. Learn to identify their seedlings so you can lift them when they’re small.
• Many self-seeders are vigorous in some gardens and not in others – ask a neighbour if they have trouble with a plant before growing it.

 

6 reliable self-seeders

Verbena bonariensis

FCT9NJ Verbena bonariensis. Argentinian vervain.

The perfect plant for the middle or back of a sunny border. It is more likely to set seed in a sandy soil than in heavy clay. Reaches 3ft 3in (1m) in height. Flowers June-October.

 

Verbascum olympicum

M4J7D5 Verbascum olympicum, olympian mullein. Image shot 07/2017. Exact date unknown.

A perennial that often dies after flowering and setting seed. Perfect for the back of the border, reaching 6ft 6in (2m) in height. Wonderful yellow flowers in summer.

 

Centranthus ruber

DH1B2R Red Valerian

Commonly known as red valerian, this attractive perennial can have crimson, white or pink flowers mall summer. Thrives in poor soil and a sunny spot. Height 1ft 8in (50cm).

 

Erigeron karvinskianus

F57D25 Erigeron karvinskianus. Fleabane flowers.

Easily mistaken as a rather healthy bunch of lawn daisies. Perfect for cracks in paving and flowers June-October. Fully hardy. Reaches a height and spread of 1ft (30cm).

 

Aquilegia

There’s an army of different aquilegias to choose from. They commonly cross-pollinate so, after time, you’ll have a rainbow of colours. Perfect for semi-shade. Average height 50cm.

 

Anthriscus sylvestris ‘Ravenswing’

EH6A15 Anthriscus sylvestris 'Ravenswing' - Dark Stemmed Cow Parsley

A short-lived perennial with deep-purple foliage. The pink-tinged flowers are a wonderful addition to a cottage garden. Sun or semi-shade. Height 3ft 3in (1m).

 

All photographs: Alamy

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