Once you've got your seeds, the next step is to sow them. How, when and where you sow your seeds will depend on many things - the type of seeds, how many of them you have, how many plants you want to end up with, what your growing conditions are, and, to some extent, what's considered normal in your area. This page tells you how I sow my seeds, gives you more general information about seed sowing, when's the usual time to sow, details of winter sowing and sowing seed in paper towels, the basic rules for success, and some Frequently Asked Questions and Links to sites with more information on seed sowing.
These are the methods I use, more or less:
I sow all my seeds in small square plastic pots, in a compost of 50/50 loam-based John Innes No. 2 and a peat-based multi-purpose compost. 15 of these pots fit in a standard seed tray.
When I sow seeds outside, I put the trays in a 3-shelf stand with an open front, but covered at the back and sides. After the seeds have germinated, I move the pot to an unheated greenhouse until the seedlings are big enough to transplant.
When I sow seeds inside, I stand the tray on the work surface in the kitchen or in my conservatory, and I put a plastic cover on. When the seeds have germinated, I move the pot to the conservatory or the greenhouse, and leave it uncovered.
When I sow seeds in the Propagator, I put the pots in a seed tray that has a heated element in the bottom as well as a plastic cover. Sometimes, in the winter, if the Propagator is full, I stand the covered seed tray on top of the boiler, which also provides bottom heat.
When I sow seeds by the Deno method, I put the seeds between damp folded paper towel, put inside a loosely folded plastic bag, which I keep beside the boiler in the kitchen. When the seeds have germinated, I put them in a small pot and move them to the conservatory or the greenhouse.
I only sow small quantities of seed - I am only looking for one or two plants, from which I can propagate more if I want them.
Some seeds germinate better if the seed coat is nicked. I use a pair of nail clippers to make a small hole in the middle of the seedcoat. Some seeds benefit from being soaked before sowing. I usually use hot water and only soak for an hour or two. I find seeds sometimes rot when they have been left to soak for a long period - except Canna, which I find germinate better after being soaked for two days.
I do not use growlights, and I do not sow seeds in the fridge or use artificial methods of stratification. If my seeds need a cold period to induce germination, I sow them outside in the autumn/winter.
I do not use vinegar, orange juice, washing-up liquid, alcohol or any other substances to soak my seeds. If I soak them, I use water.
These are my basic rules. They're not hard and fast. It depends on what seeds I want to sow, what time of year it is, whether there's room in the propagator/kitchen/greenhouse, whether I need to make room for visitors, how impatient I am, how special the seeds are, whether it's too cold to go outside ...
General Information on Sowing Seeds:
Sowing In situ:
This simply means sowing your seeds where they are to flower. You can either sow them broadcast or in drills or rows. Sowing them broadcast means scattering them on the surface, and sowing in drills means sowing them in rows. Sowing them broadcast is a good method for sowing seeds of annuals where you have plenty of seed and want a good patch of colour. It's particularly appropriate for a mixture of types or colours. Sowing in drills or rows is good where you still want a lot of plants, but prefer to have each type in its own row.
Before sowing the seeds, you need to prepare the ground. You need to dig it to make sure there are no large lumps of soil or stones, and then rake over the surface to give a fine 'tilth' - a smooth surface with the soil broken down into small particles. To sow seeds broadcast, simply scatter them over the surface, rake them in gently, and water the ground carefully.
To sow in drills, dig over the soil, rake it, then mark out rows with a stick or the back of a hoe. Sow the seeds in the rows, then cover by raking the soil from the side of the row over the drill. Again, water gently. Small seeds are usually sprinkled evenly along the row, large seeds - like peas or beans - are usually sown singly a few inches apart. If the seedlings come up too thickly to allow the plants room to grow properly, you will need to thin them out by removing the unwanted seedlings.
Remember that seeds sown outside in the garden will need weeding, and you need to keep an eye out for damage by snails, slugs, caterpillars, birds and cats.
Sowing in seed trays:
Seeds can be sown in seed trays (called 'flats' in the US), either outside or in a cold frame or greenhouse. Fill the tray with compost - use whatever is easiest to obtain in your area, as most brands will work - and firm gently. Either sow the seed broadcast, in rows, or singly, depending on their size. Cover lightly - about the same depth of compost as the width of the seed is the traditional rule.
I like to water the compost before sowing the seeds to prevent them being washed out of place, but you can water them carefully after sowing if you prefer.
Some seeds need to be kept dark, some need light. I usually leave small seeds uncovered and poke large ones into the compost with my finger. If they don't germinate, I stir the compost with the label, which moves the seeds that were covered into the light and those that were uncovered into the dark. You may prefer to be more methodical and cover the seed tray with a newspaper. You can also cover it with a sheet of glass to prevent it drying out.
Because you are using compost, nothing should come up in the seed tray except the seeds you sowed.
Sowing in trays of individual cells:
This is a cross between sowing in seed trays and sowing in individual pots. Cell packs are plastic trays which either fit into seed trays or can be used on their own. They provide an individual cell for each seed (or group of seeds for small seeds). Sow seeds as for seed trays.
Sowing in individual pots:
Seed trays are fine if you want large numbers of plants, or if you have plenty of seed. If you are sowing a small number of seeds, particularly if they are difficult to obtain, you might prefer to sow them in separate pots for each variety. The size of pot will depend on how many seeds you have, the size of the plant, how fast it grows, and when you intend to pot up the seedlings. I use plastic pots about two and a half inches square, because 15 individual pots fit into a standard sized seed tray. For large seeds - those of trees or shrubs, for example - giving each seed its own pot will save having to disturb the seedling until it is fairly well established. For small seeds giving small seedlings, having them in a pot of their own means you can keep an eye on them easily and they won't be overlooked, as they might be in a large seed tray.
Fill the pot with compost - you can afford to provide a different mix of ingredients more suited to the individual plants if they have their own pot (adding more grit for alpines, for example). Firm it gently, water, then sow the seed, covering or not as appropriate. Some people like to add sand, grit or vermiculite as a top dressing.
Sowing seed in individual pots makes it easier to give each type of seed the appropriate care - moving them when they have germinated, for example, or keeping them in a frame if they are expected to take more than one season to germinate.
Sowing seed in a propagator:
Seeds of tropical plants usually need higher temperatures to germinate. This is most easily provided by sowing the seeds in individual pots and keeping them in a propagator. There are many types available, from large, sophisticated (and expensive) models with thermostatically controlled temperatures to a simple seed tray with a ventilated plastic lid. If you have an unheated propagator, the bottom heat these seeds prefer can be simply provided by keeping the propagator on top of a boiler. If you have no propagator at all, a couple of small plastic trays such as those used for packing meat or suchlike in supermarkets can be used. If they need to be kept in the dark, the individual pot can be put inside a plastic bag, the bag closed with a wire tie, and put in an airing cupboard or warm cupboard in the kitchen. Remember to check it every so often to see if the seeds have germinated.
Seeds of tropical plants often need to have a hole made in their seedcoat to enable them to take up the moisture they need to germinate. This is called 'scarification'. Use whatever is appropriate to the thickness of the seedcoat - Mucuna may need a hacksaw, most others can be punctured by nicking with nail clippers or filing on sandpaper. Be careful not to damage the embryo. Sometimes, they also need to be soaked in warm water before sowing.
For a recap on seed sowing and pricking out basics (with photos), click here.
When to Sow Seeds:
Seeds of annuals are usually sown in the spring. They can be sown outside when there is no danger of frost, or under cover and planted out when there is no danger of frost.
Seeds of hardy annuals can also be sown outside in the autumn. This will give them a longer growing period and a head start over similar plants sown in the spring, so they will flower earlier.
Seeds of half-hardy annuals can be sown outside in the spring, or under cover in the autumn.
If they are germinated in warmer conditions, they will need to be acclimatised to harsher conditions, by putting them outside for longer periods each day until they are finally strong enough to be able to stay outside all the time. This is called 'hardening off'
Seeds of hardy perennials can be sown in spring, summer, autumn or winter. Some may need stratification, so should be sown outside in the autumn. Some may take several seasons to germinate.
Seeds of half-hardy perennials and tropicals which are to be sown in heat may be sown at any time of year.
More about Winter Sowing:
A traditional way of sowing seeds in Europe, this is now becoming popular in the US. As growing indoors under lights is one of the most usual methods of starting seeds in America, the most popular method of winter sowing is a sort of half-way house between sowing outside and sowing indoors, with the seeds being kept in unheated propagators kept outside. As this produces a humid environment, there are still problems with aphids, leggy seedlings and damping off. In England, it is more usual to sow seeds in pots and leave them uncovered either in a cold frame or in the open garden in a sheltered place. In fact, this used to be the method also used in the United States (Prof. Norm Deno, of Pennsylvania State University, wrote in 1993 in his book Seed Germination Theory and Practice: 'A time honored procedure in horticulture and gardening has been to sow seeds in pots and place them outdoors in the fall'), but they seem to have got side-tracked and come to believe that it's essential to sow seeds indoors under shop lights.
For more information on Winter Sowing, click here.
Norman Deno and the Deno Method:
Professor Norman Deno caused quite a sensation a few years ago, when he advocated putting seeds between folded paper towels impregnated with dilute Giberrelic acid as a method for germinating difficult seeds. The paper towels were put into plastic bags and kept at temperatures of 40oF or 70oF, or alternating cycles of twelve weeks at these temperatures until the seeds germinated.
Although I only have the second edition of his book 'Seed Germination Theory and Practice', I'm not convinced by his arguments, particularly as the number of seeds he used for many of his experiments was small - less than ten in some cases, and he doesn't seem to have tested all seeds by all possible methods. But 'sowing' seeds in moist paper towels kept indoors is a great space saver, so I find his method useful for seeds which germinate quickly, so that they can be transplanted into their own pot easily, and for seeds that take a long time to germinate, as they need very little maintenance.
There are several ways of achieving the same results, but I have found this way works:
1 ~ Take a piece of paper towel, fold it in half, then half again, so you have a square. Fold it again, but open out this fold.
2 ~ Sprinkle water on the paper towel so it is slightly damp all over, not wet.
3 ~ Write the name of the plant and the date on a plant label and put it in the middle of the square, with one edge of the label on the middle fold.
4 ~ Put the seeds on the same side as the label.
5 ~ Fold the paper towel over the seeds.
6 ~ Put it in a plastic bag, and close the bag loosely.
You can put several paper towels in one plastic bag. You can write the name of the seeds on the paper towel if you like, but I found it became illegible after a while. I keep mine in the kitchen, but anywhere inside will do.
Check periodically, and when they have germinated, move them to a pot.
Rules for Successful Seed Sowing:
Always use fresh compost
Always use clean pots
Always label the seeds
Don't let them dry out
Don't keep them wet
Watch out for predators - snails and slugs can get anywhere!
Improvise - use whatever you have that will give the seeds the conditions they need to germinate.
Don't be afraid to experiment - often, one 'expert' will tell you a particular type of seed needs to be stratified, and another 'expert' will tell you it needs to be sown in heat. Your guess is as good as theirs.
Finally - they won't grow if you don't sow them!
Some Frequently Asked Questions about Seed Sowing
What's Stratification? ~ Stratification is putting your seeds in a moist material outside over the winter to allow the variations in temperature to act on them, so that they will germinate when conditions are warmer. Seed used to be put in layers (strata) of damp sand, but these days we usually either sow the seeds in compost, or put them in moist compost in a plastic bag, either outside, or in the fridge. Stratification is not the same as storing seeds in the fridge. They should be kept moist during stratification, and dry during storage. There is also the possibility that leaving seeds open to the weather might allow rain to wash away chemical germination inhibitors. I've seen posts suggesting that people should stratify seeds before sending them to others. I am horrified by this. I think it must be due to not understanding what the stratification process is. You wouldn't dig up seeds you'd already sown and put them in an envelope to be shuffled around the postal system for a week or so, would you?
What seeds can I Winter Sow? ~ In the Germination Results Tables, everything with a number under Outside in the Autumn or Winter columns has been sown outside - around 500 species. If you're used to sowing seeds inside under lights, be prepared for your seedlings to grow more slowly outside in natural conditions. Anything which grows naturally in your locality, either as a wild flower or that self-sows in gardens, can also be sown over the winter. Seeds of tropical plants should not be winter sown in cold areas; they don't need stratification, they won't germinate until the weather warms up, and they could be killed by frosts.
What's the right way to germinate my seeds? ~ There is no right way to germinate any particular type of seeds. You need to find the right combination of moisture and temperature that suits your particular seeds. If you look at several different germination instructions, you'll find they often give the opposite advice for a particular seed. There are methods which have been found over a long period to be the most effective for germinating particular species, but every seed is an individual, and might be satisfied with some different set of circumstances.
How long are seeds viable? ~ There's no answer to that, either. Some seeds are best sown fresh, some seeds do die in a few weeks, but most seeds will remain viable for several years if kept in a cool, dry place.
Are seeds poisonous? ~ Some seeds or other parts of some plants are poisonous. There's a very comprehensive list of these plants on this page. This doesn't mean that all parts of these plants are poisonous, especially as the list includes almost every plant we use as food (peas, carrots, potatoes, coconuts), but that there might be a risk that some part, or product (oil, for instance), of some members of that plant family might have some ill-effects if eaten. I've always found the best approach to this is to find out what's dangerous and teach your children. My own children have never shown any inclination to eat foxgloves - or cabbage!
Links to Other Websites about Seed Sowing
Seed Sowing and Transplanting in pictures
Tom Clothier's Seed Germination Database
Seed Germination Theory and Practice by Norman Deno - about the book.