The Beginner’s Guide to Seeds and Plant Division - making your garden go further
Whether you want to thicken out the planting in your garden because it is new, and you want to add temporary colour, or well established and gaps have developed, then you don’t always need to visit the nursery to buy new plants (although that is an option).
Instead you can use seeds, or divide existing perennial plants, to fill space at ground level and either develop your scheme or add a season’s wort of colour.
SOWING SEEDS IN YOUR GARDEN
When it comes to seeds I am in the camp of working with nature wherever possible, and so making my life easier. You can therefore learn to propagate plants indoors or in a greenhouse, sowing them, pricking them out, and growing them on…but this can be too much work for many gardeners.
I therefore usually advocate sowing the seeds directly outdoors, where they are intended to grow. Not all seeds can be planted in this manner (for example I wouldn’t plant sweet pea seeds directly in the ground - I have tried it and the results were patchy) but most hardy annuals, as well as perennials and biennials if planted out in early summer, can be sown directly into the ground outside.
First you need to clear the soil where the seeds will be sown (removing perennial weeds with their roots), and then loosen the soil. It doesn’t have to be dug over, or raked too deep though as the general rule of thumb is that seeds need to be covered only to roughly their own depth of soil below ground (where very fine seeds are scattered on the surface and tapped into the soil but larger seeds should be covered). Everything then needs watering in with a fine sprinkler, so as not to disturb the seeds. As they germinate and grow you may then need to remove any weeds and thin them out a couple of times (you’ll be able to tell the difference between the mass of plants you’ve planted and the interloping weeds). I do thius is two waves; first so that the strongest plants are around 5cm apart and then later so they are about 10cm apart. Those seedlings that are removed could then be either planted elsewhere or composted.
DIVIDING PERENNIALS FOR MORE PLANTS
Alternatively you can fill out your borders by digging up old perennials (those that have flopped from the middle, died in the middle, or are simply overgrown in their current spot) and dividing them into 2 or 3 clumps - replanting one in its original position and others into gaps elsewhere in your borders. Vigorous perennials can be divided after around 3 years, although those plants that take longer to establish (sedums, irises etc) should really be left for at least 5 years if possible.
The process of division however is simple. Trim back the plant as low as possible (without removing all of the foliage and ideally retaining young fresh growth), and then dig out the plant ensuring you get as many roots as possible. Then with a (relatively sharp) spade divide the plant into 12-15cm clumps, chopping from the top and down through the roots. Then remove any weed seedlings, dig a hole, and replant.
There is a lot more to growing and propogating your own plants that you can read aboout but essentially gardening really is as simple as outlined above - as long as you have the right plants for your garden, in seed or divided perennial form, then they will naturally want to grow and you can harness their nature to expand and develop your garden in new and exciting ways. This can be to bulk up and enhance your existing scheme or it can be to add colour and interest where there are gaps. This can be done effectively in the first year or two after a new garden has been installed, through adding seeds to create colour in the areas where the plants you have will fill in a few years time once they have established. Forget me nots, foxgloves and many others work well in this regard - but make sure you don’t plant so many seeds, against your existing plants, that they deprive them of light and reduce their capacity to grow and infill those spaces. In this case less really is more.