Seed sowing guide.
General comments
We would recommend using Peat-free compost and we use Melcourt Sylvagrow multipurpose compost. Sylvagrow is lovely and loose and light, you can always sieve it a bit if you feel there are larger chunks in there but we never have. Care needs to be taken with watering as it can dry out on the top but still be moist underneath but once you have used this compost for a bit you soon get used to it.
If sowing in trays and pots, once sown it’s better to water from below so sit them in trays of water to allow the water to soak upwards through the compost. If you water from above you can move the seed around, especially light seeds they can get washed to one end of the tray and all germinate there in one big mass!
Seed is precious and if possible you should sow the seeds individually, some seeds are so small that this is almost impossible but in this case just sow as thinly as possible. Just sow what you need. The rest will often keep for another year at least.
Label your seed trays well, I’ve made this mistake a few times and think I will remember but you never do!
If sowing direct, prepare the bed by clearing any weeds and raking over so that the soil is nice and loose and friable (posh word for crumbly and light!). Then you can either broadcast sow, this is where you sow seed over the whole area, or you can sow in rows. The advantage of sowing in rows is you can spot any weed seeds that germinate in between the rows and can confidently remove them!
This is just general advice but just find a way that works best for you, there is often no right or wrong so just have a go and experiment. If you are unsure, just sow a small amount of seed then if it fails you can try again, the best way to learn is by just doing it. You will soon work out the best methods that suit you and your growing conditions.
Most hardy annuals can be sown in early spring (March–April), some also benefit from sowing in the autumn, kept protected over winter from the worst frosts and then plant out in April for flowering earlier than the spring sown plants. Or they can be sown directly once frosts have past. These different sowing times means that you will get flowers over a longer time if you need successional flowering for your cutting patch.
Amaranthus caudatus red. Small orange seeds. Sow direct in rows once risk of frost has past, cover lightly with soil and once germinated this to 50cm apart. Or sow undercover with some warmth in modules or 9cm pots. Prick out and pot on as needed and plant out at least 50cm apart. These make big tall plants that will need some staking.
Ammi majus and Ammi visnaga. Smallish grey seeds. Can be sown in early spring or in the autumn for early flowers the next year. Sow individually into 9cm pots, or into a seed tray and prick out into 9cm pots. Plant out in April or May in final positions about 30cm apart. Ammi majus can get very tall from an autumn sowing and Ammi visnaga can produce quite chunky plants so both benefit from staking well. Can be sown direct in late Spring, in rows where they are to flower.
Borage. Sturdy black seeds that can be sown direct into the ground in April or May or if you want to start a bit earlier in March can be sown undercover into 9cm pots or modules. Plant 1cm deep and pot on before planting in final positions 25cm apart. Often seeds around once established.
Briza maxima. Large beige husk like seeds. Another plant that once established will seed around at will, but to get going it’s easiest to sow directly in the Spring. Prepare the area and broadcast sow. Thin out if needed but they can cope with being close together.
Calendula (C. ‘Indian Prince’, ‘Snow Princess’ and ‘Art Shades’). Gorgeous curved seeds like little seahorses. Can be sown in early spring or in the autumn for early flowers the next year. An easy annual to sow directly, 1cm deep, where they are to flower or can be sown undercover in 9cm pots or modules. Plant out into their final positions about 30cm apart.
Candytuft ‘Crown Mixed’. Small brown seeds. Can be sown in early spring or in the autumn for early flowers the next year. Or can be sown directly once the frosts have passed. Surface sow on the compost in seed trays or 9cm pots, in spring they will need some warmth. Prick out individually into 9cm pots. Plant into their final positions 10cm apart.
Cornflowers. Centaurea cynus ‘Black Ball’, ‘Blue Ball’, ‘Purple Haze’ and ‘Classic Romantic’. Cute seed like little shaving brushes. Another easy one that can be sown in early spring or in the autumn for earlier flowers the following year. Or can be sown directly once the frosts have passed. Sow straight into 9cm pots or in a seed tray and prick out individually when germinated. Plant into their final positions 15cm apart. Will need supporting.
Cerinthe. Large black seeds. Can be sown in early spring or in the autumn for earlier flowers next year. Or can be sown directly once the frosts have passed. Sow straight into 9cm pots or modules, 1 seed per pot or cell. Plant out once the frosts have passed.
Chrysanthemum ‘Rainbow Hippy Lovechild’. Large brown husk-like seeds. Sow in the spring with some warmth spring or in the autumn for earlier flowers next year. Sow into 9cm pots or seed trays prick out individually into 9cm pots and plant out once the frost has passed, 20cm apart. Can also be sown direct in late Spring.
Corncockle. Small black round seeds. These do best sown directly where they are to grow, this can be in the spring or in autumn. Sow 1cm deep and thin to 30cm apart. Can also be planted undercover in modules and transplanted in the spring. They can get very tall so may need some support.
Daucus carota. Small grey seeds. Actually a biennial really but it does well sown as an annual, we tend to sow in the autumn though and they are good to sow directly. Only lightly cover with soil. Alternatively sow in seed trays or modules and prick out while still very small into larger pots. Can also be sown in early spring. Will self-seed if seedheads left over winter.
Dill ‘Mammoth’. Oval brown flat seeds. A nice easy one, sow indoors in early spring for early flowers or direct once the frosts have passed. Sow on the surface on seed trays or into 9cm pots, only lightly cover with compost. They can get very tall so may need some support in the garden. Space about 15cm apart.
Eschscholzia ‘Ivory Castle’ and ‘Orange King’. Small round black seeds. These really do prefer being sown directly as they don’t really like transplanting. Can sow in rows or broadcast sow and just cover with compost/soil. Sow in the spring.
Godetia ‘Crown’. Very small black seeds. Sow directly in spring or undercover with some warmth in early spring. Can also be sown undercover in autumn for earlier flowers. Sow in seed trays and prick out or straight into 9cm pots and they germinate quickly. Plant out after the frosts about 15cm apart.
Gypsophila ‘Covent Garden’. Small black seeds. Sow direct or for earlier flowers sow undercover in early spring. Pinch out to make more compact and bushy. Thin to spacing of about 25cm.
Larkspur ‘Giant Hyacinth’ and ‘Imperials Mix’. Small black seeds. These can sometimes be tricky to germinate as they need a period of cold to break dormancy. So you can either sow in autumn or late winter to allow the natural cold conditions to break the dormancy. Or put the seed packet in the fridge for a couple of weeks before sowing. Sow into seed trays and prick out into modules or 9cm pots. May need some support.
Nigella papillosa ‘Delft’, N. ‘Alba’, ‘Oxford Blue’ and ‘Persian Jewels’. Small black round seeds. These are best sown direct as they don’t really like transplanting, but I have sown in modules successfully too. Can sow in rows or broadcast sow and just cover with compost/soil. Sow in the spring or in autumn for earlier flowers.
Night scented stock. Small brown seeds. Very easy to grow and best sown directly where they are to grow in the spring. Broadcast sow and lightly over with soil. Can thin out if needed to about 20cm apart.
Phacelia. Small black seeds. Another easy one that is best sown directly, broadcast sow and cover with soil. If growing for cut flowers you may want to thin out a bit. If growing as a green manure then best to dig it in before its starts to flower and leave for a couple of months before planting in that area to allow it to breakdown naturally.
Salvia viridis and Salvia viridis ‘Oxford Blue’. Small black seeds. Best to sow directly in the spring after the frosts, sow in rows or broadcast sow, thin out to about 15cm apart. Can also sown undercover into seed trays, pricked out individually into pots and plant out after the frosts.
These are susceptible to frost and so if you are sowing directly they need to be sown once the risk of frosts has passed. They can often be started earlier than that if you sow them undercover with some warmth and grow on. Then you only plant them out once the frosts have passed. They may need hardening off before planting out which just means bringing them out of the protected area in the day and taking back indoors overnight, do this for a couple of weeks. This is just so that they don’t get a shock from being in a toasty greenhouse/house to getting planted out in the colder outdoors. It just keeps them growing more smoothly.
Antirrhinum majus ‘Lucky Lips’. Small black round seeds. Sow undercover from January as they are quite slow growing. Surface sow onto a seed tray, don’t exclude light. Prick out the tiny seedlings in pots. Plant out in final position once frosts have passed. Plant 30cm apart.
Aster ‘Ostrich Plume’. Oval beige seeds. Sow undercover with some warmth in April, sow thinly on the surface of the compost in a seed tray or 9cm pot. Once germinated prick out individually into 9cm pots. Plant out in final positions once the risk of frosts has passed, when they could also be sown directly. Plant 20cm apart.
Cleome ‘White Queen’ and ‘Violet Queen’. Small black seeds. Sow undercover with some warmth in April, sow thinly on the surface of the compost in a seed tray or 9cm pot. Once germinated prick out individually into 9cm pots. Plant out in final positions, about 30cm apart, once the risk of frosts has passed.
Climbing Black Eyed Susan. ‘Flash Mix’. Unusual spherical seeds like little sea urchins. Sow under cover with heat in late autumn-winter or in spring. Sow onto compost in 9cm pots and cover lightly. They need warmth for germination. Grow on and keep protected from frost. Plant out when risk of frosts has passed. Will need a climbing support.
Climbing Nasturtium. Pea-sized grey seed. Perfect for sowing direct or can sow undercover straight into 9cm pots and grow on, sow or plant out once the frosts have passed.
Cobaea scandens. Large flat seeds. These are the first things we sow in the year, they like a good long growing season to grow well. Sow 1cm deep in 9cm pot in February or March, they will need warmth to germinate. Keep protected, they can grow fast so I often pot on again into 11cm pots with some support. Plant out once the frosts have passed. They need a good strong climbing support as they are very vigorous.
Cosmos ‘Apricotta’, ‘Fizzy Rose’, ‘Purity’ and ‘Sensation’. Long thin black seeds. Sow with some heat undercover in seed trays or in 9cm pots. Prick out individually if needed in to 9cm pots. They germinate super speedily so be aware that they grow quickly but can’t be put outside until after the first frosts. They may need some support as ‘Purity’ can get very tall. Space 40cm apart.
Didiscus ‘Blue Lace’. Small flat seeds. Sow with some heat undercover in seed trays or in 9cm pots. Cover with compost. Have patience they can take a couple of weeks to germinate. Prick out individually in to 9cm pots. Plant out once the frosts have passed. Plant out 20cm apart.
Helianthus ‘Harlequin’, ‘Moonwalker’, ‘Red Sun’, ‘Valentine’, ‘Summer Lovin’. Nice big teardrop-shaped seed, some are stripy. Super-duper easy and another one which is great to get kids to sow. Sow directly once the frosts have passed or undercover direct into 9cm pots. 1.5cm deep, can add two seeds per sowing and thin to one per pot. Protect from slugs when small and they will need staking once growing well.
Ipomoea ‘Heavenly Blue’. Large black seeds. Seed can be soaked in water 24 hours before sowing to aid germination. Sow directly once the frosts have passed, about 20cm apart. They will need a climbing support. Can sow undercover into 9cm pots, 2cm deep with some warmth and plant out after the frosts.
Ipomoea lobata ‘Exotic Love’. Medium sized black seeds. Seed can be soaked in water 30 minutes before sowing, so that they swell, this will aid germination. Sow directly once the frosts have passed, about 20cm apart. They will need a climbing support. Can sow undercover into 9cm pots, 2cm deep with some warmth and plant out after the frosts. Need full sun to flower well.
Malope trifida ‘Vulcan’. Small brown seeds. Sow with some heat undercover in seed trays or in 9cm pots. Prick out individually if needed in to 9cm pots. Plant out with a spacing of 30cm once the frosts have passed, when they could also be sown directly.
Nicotiana affinis, N. ‘Lime Green’, ‘Sensation’, ‘Starlight Dancer’ and ‘White Trumpets’. Tiny dust like seeds. Best sown undercover with a bit of heat in Spring. Sow thinly on the surface of the compost in seed trays or 9cm pots. They need light for germination. Prick out into individual pots once large enough to handle. They are fast growing once they get going which always surprises me from such small seed. Space all about 25cm apart, except for N. ‘White Trumpets’ which can get very tall and wide so needs about 50cm spacing.
Phlox ‘Creme Brulee’ and ‘Sugar Stars’. Small brown seeds. Sow undercover in seed trays or 9cm pots and cover with compost, give them some warmth in Spring. Prick out individually into pots and plant out once the risk of frost has passed. They can be grown quite close together as they will then support each other. Needs pinching out two or three times to allow it to bush out and then it will send out nice long stems.
Rudbeckia ‘Irish Eyes’ and ‘Marmalade’. Small black seeds. Best sown undercover with a bit of heat in Spring. Sow in seed trays or 9cm pots on the surface of the compost and lightly cover with compost. Prick out individually into pots and plant out when all risk of frosts have passed, plant about 25cm apart.
Scabiosa stellata ‘Ping Pong’. Big seeds like little shuttlecocks. Sow in the spring undercover with some warmth into seed trays or 9cm pots and just cover with compost. Prick out individually into pots and plant out once the risk of frost has passed. Plant about 30cm apart.
Statice ‘Higgledy Mix’ and ‘Sky Blue’. Small long thin black seeds. Sow in the spring undercover with some warmth into seed trays or 9cm pots and just cover with compost. Prick out individually into pots and plant out once the risk of frost has passed. Plant about 30cm apart.
Zinnia ‘Cactus’, ‘Envy’, ‘Mammoth’ and ‘Purple Prince’. Large flat black seeds. These are a seed that doesn’t like too much disturbance so they are good to be sown in modules undercover in the spring with some warmth. They can be susceptible to slugs when young so we like to grow them on into bigger pots and plant out once established into a good sized plant. Plant once the frosts have passed, when they can also be sown directly. May need some support.
These are lovely big seeds like small black mini marbles, easy to handle and great to get children sowing seeds.
These can either be sown in early Spring (February/March) or for earlier flowers they can be sown in mid Autumn, usually mid to end of October, but it will depend a little bit as to where you are in the country. When there is still some warmth to encourage germination but not too warm that they romp away and get too leggy and soft and susceptible to hard frosts. Believe me I’ve learnt the hard way!
I sow into root trainers or square 9cm pots 2 seeds module of the root trainer or 2-3 per 9cm pot. I use Sylvagrow multipurpose peat free compost and have had excellent germination for many years. Some people say that you should soak them but I have never had to do that! I let them germinate in a sunny warm spot but once germinated they can be kept in a cool greenhouse, try to grow them hard so they develop into short sturdy plants, pinch out if needed, maybe fleece them if a sustained hard frost is forecast. I plant mine out in early April, they can sit and sulk for a bit but soon settle down and start growing. The first shoots will need tying in to get them trained up whichever support that you prefer.
If sowing in spring they will need some warmth for germination but again once they have germinated they can be kept in a cool greenhouse.
You can also sow directly into the soil after the risk of frosts has passed.
Biennials are sown in May to July, I prefer sowing most things in seed trays or pots, pricking out and potting on so that I have reasonable sized plants before planting. But there are some biennials that can easily be sown direct, especially Foxgloves, Honesty, Wallflowers and Sweet Rocket. They don’t need heat for germination just put them in a sheltered spot in your garden or a cold-frame and they will soon germinate. Ideally they should be planted in their final positions before the first frost and they will stay as a small plant over winter and then start growing and flowering the following spring.
Canterbury Bells Single Mix. Small seed so I definitely prefer sowing this in a seed tray or 9cm pot and pricking out. Sow on the surface of the compost and don’t cover as they need light to germinate. They are quite slow to germinate and grow initially but then seem to put a spurt on. Pot on individually into 9cm pots and then plant in their final positions about 30cm apart. They are classed as a biennial but you can sometimes get flowers in the first year if you sow early in Spring.
Foxgloves ‘Alba’, ‘Suttons Apricot’ and ‘Excelsior’ the seed is tiny, like dust almost and so care is needed to sow thinly. It’s impossible to sow the seed individually but the thinner you sow the easier it is to prick out. They need to be surface sown as they need light to germinate. Once they have germinated and are large enough to handle prick them out individually into module trays or 9cm pots. Once rooted into these pots they will be ready to plant where you want them in the garden. These can also be sown directly, clear where you would like to plant them and sow thinly over the area. Thin out to final spacings once germinated.
Sweet Rocket (Hesperis ‘Purple’ and Hesperis ‘White’), small little black seeds. Sow thinly on the surface of the compost and cover lightly. Prick out into modules or 9cm pots. Plant into final positions once rooted, 30cm apart.
Honesty. Large flat disc shaped seeds. These can be sown singly into 9cm pots or modules. I tend to sow them seed sideways down and cover slightly with soil. Germination can be a bit erratic and sometimes they need a spell of cold to break dormancy and encourage germination. They can be also sown direct where you would like them to flower, about 30cm apart.
Sweet William (Sweet William ‘Alba’, ‘Auricula-Eyed’, ‘Nigricans’ and ‘Higgledy Mix’). Small black seeds these can be sown directly by broadcasting over the bed or in rows where you would like them to grow. Sow thinly, cover with a thin layer of soil and and thin out to a spacing of about 15cm once germinated. Alternatively sow thinly in seed trays or 9cm pots, cover lightly with compost and prick out into individual modules or pots. Plant out in final positions once rooted.
Wallflowers (Wallflower ‘Cloth of Gold’, ‘Ivory White’ and ‘Vulcan’). Small black seeds again these can be sown directly by broadcasting over the bed or in rows where you would like them to grow. Sow thinly, cover with a thin layer of soil and and thin out to a spacing of about 40cm once germinated. Alternatively sow thinly in seed trays or 9cm pots, cover lightly with compost and prick out into individual modules or pots. Plant out in final positions once rooted. Another note on these is that they don’t take well to getting root bound, pot on into bigger pots if not quite ready to plant out or plant out into final positions as soon as you can to prevent any checks in growth.
Can be a little more tricky than the annuals and biennials as germination may be more temperamental. You will need to start them off indoors, they are not really good ones for direct sowing and most need some warmth for germination.
The Dahlias (‘Bishops Children’ and ‘Cactus’) are easy, just sow in the early spring, sow thinly on the surface of peat-free compost in seed trays or in 9cm pots and cover lightly with more compost. They need a bit of heat but they germinate quickly and can be individually pricked out and potted on into 9cm pots. They shouldn’t be planted outside till all risk of frosts have passed. At the end of the year they will have developed big chunky tubers that you will need to protect from frost (depending on how cold it is where you live you can either leave in the ground and mulch or lift and store in a frost free place).
The other hardy perennials (Chrysanthemum ‘Crazy Daisy’, Echinacea ‘Primadonna Pink’, Feverfew and Gaura ‘The Bride’ all have similar requirements. They need to be sown in the spring indoors, sow thinly on the surface of peat-free compost and don’t cover as they need light to germinate or you can cover with a thin layer of vermiculite. Patience is required!! Germination can be slow and erratic. If you get no germination they may need some cold stratification to break the seed dormancy. This just means put them somewhere cold for a couple of weeks and then bring them back into the warmth again. Or you can cheat and put the packet of seed in the fridge for a few weeks before sowing and this can break down the dormancy of the seed.
The Knautia ‘Melton Pastels’ is often recommended to sow in the autumn and you could potentially sow those directly and then they will naturally have a cold spell over winter. But you could also use the fridge trick on this seed too and sow in the spring.