Growing your own plants from seed is surely one of the most satisfying tasks in all of gardening. You save (often considerable) amounts of money, you have full control over what you grow and how (so you can be sure that the whole process has been organic, for example) and you can often grow all sorts of plants (both ornamental and edible) that you wouldn’t otherwise be able to find.

Seed strategies.

Crocus seeds, cleaned and ready for sowing.

In nature plants and their seeds have evolved a whole range of strategies and timetables to ensure successful germination, so, before you begin it’s pretty important to know a little bit about whatever it is you’re trying to grow.

Plants that flower early in the growing season typically (though not always) produce seed that germinates quickly, with the new plant-lets growing to reasonable maturity in their first year. If they are perennials those young plants will then be able to harden off and over-winter successfully.

Later flowering plants (including most trees and shrubs) generally produce larger seeds that come with a more substantial built-in food supply and reinforced protection. Their strategy is to over-winter as a seed and germinate the following season (or sometimes the one after that) with rising spring temperatures. This gives the young plants an entire growing season to reach sufficient maturity to make it through the next winter.

Germination.

Whichever natural cycle your seeds are on your job is to mimic the conditions that would naturally trigger their germination.

Apart from very specialist seed (some employ fire or the digestive juices of animals for instance) there are three key factors that determine when a seed will germinate: temperature, light levels and water.

With those quick germinators – anything from 48 hours to a few weeks – this means picking a sowing time and location that will be warm, light and moist enough to trigger germination more or less immediately.

Slow germinators almost always require a cold dormancy period (known as stratification) that mimics winter, followed by a rise in temperature and light levels that signals the arrival of spring.

Timing.

Quick germinating seed can be sown outdoors once spring is well underway and temperatures are not going to dip below freezing point. Depending on what plants you’re growing the seed can be sown directly into the position that you want the final plants to be in (as you might with some vegetables or wild flowers) or into pots or seed trays, which gives considerably more flexibility in terms of end location and seedling care.

Outdoor germination can be slow and erratic (much like the weather that triggers it) and the process can be sped up considerably by artificially boosting temperatures. Even the protection of an unheated greenhouse will make a big difference, and a heated frame or an indoor windowsill will be quicker still.

Seed prepared for fridge stratification.

When germinating seed indoors it’s important not to start them off too early or the light levels will be insufficient to support the seedlings and you’ll end up with weak, spindly plants that are forever trying to reach the light. Generally, any time from early spring is ideal.

Seed that requires a period of stratification can be sown into pots outdoors in autumn and, so long as they are protected from marauding seed-eaters, they will germinate naturally with the coming Spring.

Alternatively you can provide an artificial dormancy by sealing the seed, together with a little compost, in small plastic bags into the fridge for 60 to 90 days before sowing in the usual way. This strategy that allows such seed to be started at any convenient time of the year.

Sowing.

If you are sowing in any way besides using the open ground then you really only need four things for your seeds: a container, some compost a transparent cover and a label.

The container can be a plant pot or a purpose made seed tray, but old margarine and fruit and vegetable containers do at least as good a job – make sure they have lots of drainage holes puncturing the base though.

Compost should be very free draining. Seeds germinate very well in pure perlite, vermiculite, fine grit or coarse sand, although they will need to be moved on whilst still very young before they exhaust their in-built food supply. A 50/50 mixture of any of those same materials with a good compost is ideal and will allow the seedlings to stay in their nursery a good deal longer.

Scattering to sow medium/fine seed.

I like to sterilise everything – pots, and compost – with boiling water first, it prevents or at least reduces the occurrence of algal slimes, mosses and other wind-blown seeds that would otherwise hinder the new seedlings.

Fill your chosen container around 2/3 full of the compost mix, and sow the seeds onto the surface.

Very fine seed can be scattered, larger seeds placed and spaced individually, taking care not to sow too many into one container  – much better to save some seed or sow a second or third potful.

The sown seeds should then be covered to roughly their own depth with compost, or better still with sterilised perlite, vermiculite, fine grit or coarse sand. Very fine seed does not need to be covered at all, and can simply be surface sown.

New seedlings in a plastic-bag tent.

Don’t forget to label your seeds at this stage. It’s useful to add the date of sowing along with the name of the plant and possibly, with larger seeds at least, the number that were sown, which helps you keep an eye on germination rates

The final, but crucially important stage is to cover the whole pot. You can use a sheet of glass, cling-film or plastic, but I find the best strategy is to use a clear plastic bag to form a little tent that can be secured with a rubber band if it’s not the greatest fit.

The bag creates a little mini-greenhouse, with a stable environment that allows full light through but keeps a high and even moisture level where no watering is required.

Pricking out.

Carefully potting up a young seedling following pricking out.

Once the seeds have germinated they can be left in their little tented pots for quite some time, depending on how large the young plants are.

The plastic bags should be pierced to gradually acclimatise the seedlings to the lower humidity levels outside. Within a few days the bags can be removed altogether and the pots placed in a light, protected position, which may be indoors or outdoors depending on temperatures/seasons etc.

Once they are strong and stable enough the young plants can be pricked out, either for further growing on in individual pots or for planting in their final positions.

If using a margarine pot or similar it’s easiest to cut the pot open and gently divide the seedlings up. Whatever type of container they have been germinated in it’s crucial to avoid any damage to the young root systems and very delicate stems at this stage and the seedlings should only be handled by their leaves.

Young Sarracenia plants - potted up and growing on.

As ever, replant with the compost same level that the plants were at in their germination pots and, if potting on, you can now use a slightly richer, and more compost-rich (though still very free draining) mixture to help feed the plants.

Remember to keep an eye out for slugs and snails and position/protect accordingly – just one rampaging mollusc that can almost instantly decimate an entire crop of new seedlings.