Eugene is an avid gardener and has been passionate about growing things for over 40 years.
How to Sow Seeds in 10 Easy Steps (With Pictures)
You can buy "ready made" plants in a store, but it can be much more fun and a lot less expensive to grow them yourself from seed. The magical phenomenon of a seed's germination and transformation into an adult plant is entertaining for both adults and children alike!
In this guide we'll discuss
- Collecting seeds (from poppies)
- Trays and other containers for sowing seeds in.
- Which growing medium is best
- Details on sowing seeds
- How you should look after seeds once they're sown
- Getting ready for planting out
- What are the easiest flowers to grow from seeds
- Seed germination and seedling problems
- Alternative methods of propagating plants
Is it easy to grow plants from seeds?
Seed sowing is a basic horticultural skill. Many flowers, trees, and vegetables are easy to grow from seed if you take a little bit of care. Minimal equipment is needed and all you need to do is provide the basic requirements for germination; warmth, moisture and oxygen.
One obvious advantage of growing plants from seed is that it is much cheaper than buying them. Also many plants produce lots of seeds which can easily be harvested and sown, and you can collect more seeds than would ever be included in a store-bought packet.
What you'll need:
- the seeds themselves
- containers: you can use discarded plastic cups, trays or boxes
- seed compost (potting soil made especially for starting seeds)
- a spray mister (empty spray bottles are ideal)
Steps for Sowing
These are the basic steps, but check the seed packet for specific details on sowing depth, germination temperature and when to sow.
Step 1: Harvest Seeds From Flowers and Vegetables
The seeds I sowed were collected or harvested from flowers in the autumn after flowering.
- Pick a dry day for collection.
- Shake seeds into a paper bag or envelope (not a plastic bag, which will retain moisture and promote mold). Some plants have pods which are just another shape of ovary. You can split these open yourself and collect the seeds, but some pods are "spring loaded" and twist and split open themselves, flinging seed everywhere, so collect those seed before this happens.
- Store seeds in a cool, dry place until you're ready to sow them.
When are seeds ready to be collected?
Collect seeds when the ovaries (seed pods) are ripe. You'll know this because they'll usually have become crisp, dried-out, and beige in color. Sometimes, with plants like marigolds, the ovary will split open, revealing bunches of seeds. Other flowers have a capsule-like ovary. A tell-tale sign that seeds are ready is that you can hear them rattle inside when you shake the seed pod.
Will flowers grown from seed be like their parents?
Not necessarily. Flower varieties are often bred to have certain attributes such as large, abundant or colorful blooms or nicely shaped petals. Quite often if you sow seeds, the flowers produced will revert to what the original wild version looked like. We'll learn more about this later.
Step 2: Collect Trays or Pots and Drill Holes If Needed
You can sow seeds in a proper seed tray bought from a store. Alternatively, you can make do with a cookie tin, flower pot, empty food container, or something like that. If there are no holes in the bottom of the container, make some with a 1/4 inch drill bit or a nail. Space the holes a few inches apart. This allows water to drain from the container and prevents it from collecting, which would make the seed compost overly wet.
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You can also sow seeds individually in plant trays like the ones annual plants from stores are sold in. The advantage of these is that seedlings don't need to be transplanted later. If you have lots of seeds and not enough trays, sow a couple in each compartment in the tray in case one doesn't germinate.
Step 3: Fill the Container With Sterile Seed Compost (Seed-Starting Potting Mix)
Use a sterile seed compost like this seed starting potting mix from Amazon if possible. You can also use a multipurpose seed/potting compost, but don't use soil dug up from your garden, as this will be lumpy, contain lots of pests and diseases, and dry out quickly. Some plants aren't "fussy" about what they grow in, and if you have lots of harvested seed, you can try sowing it in soil which you have crumbled up so that it's nice and fine. From my experience however, it's best to buy proper compost to maximize the chances of germination.
Step 4: Moisten the Surface of the Compost
Moisten the surface of the compost with a mist spray. I just use an empty recycled window or shower cleaner bottle (carefully washed out before using). You can use a watering can but unless its sprinkler rose has small holes, it will flood the compost. Don't use a watering can to wet the compost pre-germination if it becomes dry, or to water delicate young seedlings, because too much water will wash away seeds or flatten seedlings.
Step 5: Sprinkle the Seeds Evenly Over the Compost
Sprinkle small seeds over the compost from the palm of your hand using your finger. Don't cover small seeds with soil, as it can smother them. Larger seeds can be placed one by one on the compost and then covered with a sprinkling of compost. Much larger seeds (such as sweet corn, sunflowers, and tree nuts) can be pushed down below the surface of the compost about 1/4" / 6 mm.
Step 6: Cover the Seed Tray and Place It in a Warm Spot
Cover the seed tray with a piece of glass, a magazine, a slate, a piece of plastic, plywood or whatever. This prevents the compost from drying out and keeps the seeds in the dark, which aids germination. However seeds may alternatively require diffuse light for germination, so again, consult the seed packet or Google for specific details.
Seeds sprout best at a temperature above 64F (18C). In the northern hemisphere, it's best to sow seeds in early spring around February or March so the plants can have a full growing season. If you live in a climate with cold winters, it may be too cool for germination, so you can place the tray in a plant propagator (or alternatively locate it in a hot press close to a hot water tank or near your furnace/boiler).
Check the seed tray after a couple days, and then keep checking it for signs of germination. The trick is catching them in time: some seeds sprout quite quickly (within days) while others take weeks.
Step 7: Uncover the Seedlings Once They Germinate
It's very important to uncover the seedlings and expose them to light once they germinate, otherwise they will rapidly become straggly, with overly long, thin stems.
- If the plants are sensitive to frost, they will need to be kept indoors in full sun, in a greenhouse, or under a cold frame. During severe frosts, seed trays should be brought indoors or covered with insulation to protect them from freezing.
- Place the seed tray on a windowsill where it should get enough light.
- Turn the tray each day so the seedlings are evenly lit.
- Keep the compost moist with a spray mister. This is essential, especially if the seeds are at or close to the surface, as those tiny roots can dry out rapidly when exposed to warm sunshine or warm air in a room.
- Check daily and water if necessary. Once seedlings have a few pairs of "true leaves," they're ready for the next step.
Tip: Avoid strong sunshine on trays of small seeds sown outdoors. The surface of compost can rapidly dry out, especially if it's windy, and the seedlings may perish. It's probably best to keep them out of direct sunlight until a few pairs of leaves appear.
Step 8: Transplant the Seedlings to Individual Pots
Once seedlings have grown a few pairs of "true leaves" and are big enough to handle without damage, they can be transplanted into individual pots or trays. Some seedlings are quite small and delicate, so it's best to wait until they get bigger.
- Water to loosen the compost and then gently tease the seedlings out using a popsicle (ice pop) stick, teaspoon, or similar. Try to avoid damaging the delicate roots.
- If seedlings are small, it's best to hold the leaves between your fingers and pull sideways to disentangle the roots from adjacent plants rather than pulling upwards, which can cause breakage.
- In the new pot, make a hole a with your finger or the popsicle stick in the compost, drop the seedling into the hole, and gently press the compost back around the roots.
This guide shows you how to make your own compost:
Gardening for Beginners: Composting Without a Compost Bin
Step 9: Keep Transplanted Seedlings Out of Direct Sunlight While They Establish Roots
This is important if it's hot and sunny. If you didn't manage to keep a little piece of compost stuck to the roots and they were bare during transplanting, the exposed roots can dry out rapidly. So keep seedlings out of direct sunlight (but not in a dark or overly shaded spot) for a week until the roots grow into the new compost and have a better chance of absorbing moisture. In dull, overcast weather, you don't need to do this.
Step 10: Harden Off and Plant Out
Once plants have reached the stage where their roots are starting to emerge from the bottom of the pot, they can be planted out to their final location.
Plants that have been grown inside need to be "hardened off" or slowly acclimated to the outdoors over a period of about seven to 10 days. Gradually introduce them to direct sunlight, dry air, and cold nights so that they don't suffer shock from the sudden change in growing conditions.
Plants can be hardened off by placing them in a wind- and sun-shaded spot outside, exposing them to these conditions for an hour a day, then taking them back inside at night. Extend the time gradually by an hour a day so that they become accustomed to lower temperatures. Start hardening off half-hardy annuals (e.g. marigolds, petunias, asters) shortly before the last frosts so plants are ready to plant out.
When Should Seeds Be Sown?
Sowing too early means that the plants are ready too soon and can get pot-bound before they can be planted out after frost has passed. Sowing too late means they don't flower until late in the season.
When to start seeds indoors:
- Hardy annuals, the best time is 8 to 10 weeks before the last frost (check frost guide for your zone). Then transplant them to the garden as seedlings a month later. Unlike half-hardy seedlings, they won't be affected by frost.
- Half-hardy annuals, sow 6 to 8 weeks before the last frost. (In the UK, you can generally sow half-hardy annuals in Feb/Mar for planting out after hardening off in mid to late May when bad frosts are unlikely.)
When to sow seeds outdoors:
Hardy annuals can be sown outdoors in early spring when ground conditions allow. Alternatively sow in autumn (fall) so they germinate and partially develop before winter. This gives them a head start for continued growth in spring.
What is Direct Sowing?
This is when you sow seeds directly in the ground in their final location rather than sowing them earlier indoors in containers and transplanting outside. The advantage is that young plants don't have to be transplanted, however on the downside, young seedlings can be swamped by weeds. You can kill weeds pre-sowing by using black plastic to cover ground in late winter and leaving it in place through early spring. Another technique called soil solarization involves laying clear plastic over the area you intend to sow on for 6 to 8 weeks during hot weather. Heat builds up under the plastic and kills weeds, along with some pests and pathogens.
How Do You Sow Seeds Outside?
You can sow seeds directly in the ground. This is often done with vegetable seeds or hardy annual flowers.
- Seeds should usually be sown in early spring as recommended on the packet.
- Dig the ground and turn over the sod to a depth of about 4 to 6 inches. This is best done before winter so it can be left for several months for frost to break up the soil. Alternatively, slice off the top inch of vegetation.
- Loosen soil with a fork or use a chopping motion with a spade to break it up.
- Rake the soil to a fine tilth so that it's fine and crumbly. Remove stones, weed debris, roots, sticks etc.
- Use a line as a guide if you're sowing vegetable seeds. This helps to keep things neat and makes it easier to walk between rows. If you're sowing flower seeds, you can scatter and rake them in rather than sowing in rows.
- Space the seeds and sow to the recommended depth. A rule of thumb is that depth should be three times the diameter of a seed. Press small seeds into the ground. If you've got lots of seed to spare, sow a few together at each spacing to maximise the chances of germination. You can thin and transplant excess seedlings later. If sowing large seeds, use a pencil, lollypop stick or similar to make a hole. Alternatively you can make a long furrow or groove in the ground and sow into this.
- Use a fine spray mist to moisten the ground.
- Thin seedlings once they germinate
What Does "Germination" Mean?
A seed is an embryonic plant in a capsule, with all the DNA information present to eventually develop into a full grown "adult". If the environmental conditions are right, a seed breaks out of its husk or shell and begins to grow. It sends a shoot upward to search for light and it also sends a root downwards, attracted by gravity. This process is known as germination.
How long do seeds last?
Seeds are dormant. This means that they do nothing and, in effect, are "asleep" as long as they are kept in a cool, dry place. Some seeds have a "best before date" in the sense that they will eventually deteriorate over time. However, some seeds can be stored for decades before they grow. In fact, the oldest known seed that was successfully germinated was from a date palm estimated to be 2000 years old. This was successfully grown in 2005.
What does a seed need to germinate?
Seeds have three major requirements for germination; water, oxygen and warmth (the temperature depends on the specific seed). Some seeds also require light but others require dark conditions.
Diagnosing Seedling Problems
- Leggy seedlings are the result of insufficient light after germination.
Solution: Move seedlings grown indoors as close as possible to a window as soon as they sprout.
- Seedlings that are shriveled or toppled over is seen in cold, wet conditions that cause a damping off disease. Pathogens kill or weaken seeds pre-germination (or shortly afterwards).
Solution: Try to provide adequate light, heat and ventilation and avoid overwatering.
What Are Annuals, Biennials and Perennials?
- Annuals are plants that complete their growing cycle in one season between spring and fall (autumn).
- Half-hardy annuals are annuals that are tender and susceptible to frost. They need to be sown indoors in spring and planted out once the danger of severe frosts has passed.
- Biennials germinate and partially grow in size between spring or summer and fall. The next year they grow more foliage and finally flower.
- Perennials are plants that germinate and may flower the first season. They re-flower the next year and last indefinitely. Trees and shrubs are perennials as well as herbaceous plants (plants with soft green stems and not much wood). Heerbaceous plants often die down to ground level at the end of the year and sprout new foliage in spring.
What Flowers Are Easy to Grow From Seed?
- Annual poppies
- Canterbury Bells
- Oriental poppies
For more info, see my guide:
Assorted Vegetable Seed Packs
Ideal for kids who want to try growing their own veg, this seed assortment from Amazon should get them started! The 43 variety selection includes seeds for growing familiar vegetables such as carrots, tomatoes, melons and beans.
Wildflower Seed Mixtures
This wildflower seeds pack from Amazon is great value. The packet consists of 16 individual species of wildflowers. Popular favorites such as Black-Eyed Susan, Purple coneflower, Columbine, White Yarrow & More! Contains 100% pure live seed, no fillers or inert matter. Seeds are non-GMO and very easy to germinate. Ideal for a wild corner of the garden and great for attracting bees and butterflies. Height ranges from 12 to 48 inches tall.
Propagating Plants From Cuttings
Some flowers, shrubs or trees are difficult to grow from seed because of the length of time or strict conditions required for germination. So sometimes it's easier to make new plants by taking cuttingst. You can read all about it in my other guide, 7 Easy Steps to Taking Plant Cuttings.
Why grow from cuttings instead of seeds?
The advantage of growing from cuttings is that the new plant is like a clone and genetically identical to the plant it came from. Plants grown from seeds don't necessarily "breed true" and, just like humans, can look somewhat differently to either of their parents, because they share DNA from both of them. Also it takes longer for a plant to grow from seed.
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This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Questions & Answers
Question: I germinated some seeds on a paper towel. Do I plant the seedling with the pod down or the shot down?
Answer: The shoot should point upwards and the root downwards. Even if they don't and the germinated seed is planted "upside down" and before leaves appear, the shoot and root eventually reorientate themselves. So a shoot will turn around and travel upwards towards the light and the root will detect gravity and grow downwards.
Question: Do sunflower seeds need darkness to germinate?
Answer: It doesn't seem to matter. You can cover the seeds or leave them uncovered. When growing small seeds that are near the surface, it's often better to cover the seed tray/container to stop the seed compost from drying out in strong sunshine.
Question: The seed packets sold in stores are dated. Do the seeds really "expire" after the date?
Answer: It's probably an estimate assuming that moisture in seeds, combined with bacteria and molds will eventually lead to their demise if they aren't given the opportunity to germinate. However, I've never really checked packets to see whether the expiry date on some is further into the future than on others. Everything now seems to have an expiry date, so maybe the seed packers are just covering themselves to avoid people complaining about seeds not germinating. Apparently keeping seeds in the fridge prevents them attempting to germinate and then failing and dying when there's no growing medium present, so that may extend the lifespan. Some seeds have a very long lifespan, perhaps hundreds of years. If you have a packet which has gone past the expiry date, all you can really do is sow them and see what happens!
Question: I've bought soil for bean seeds. They have shoots now, and two to three leaves. When is the appropriate time should I put in fertilizer?
Answer: You can give the seedlings a liquid feed from now on. Usually, it's best to use one-quarter to one-half strength solution, but consult the instructions on the pack to see whether it needs to be weaker. Feed once a week, and use plain water if necessary between feedings. Once the seedlings are planted, you can use one half to full strength solution, every week or so. If you're using granular fertiliser, don't let it come in contact with leaves or stems, as it can burn. Too much fertiliser can cause seedlings to grow too fast and become spindly. If this is happening, ease off on application (spindly seedlings are also the result of lack of sufficient light).
Question: I've planted strawberry seeds. They are in my home, on a table. I water them twice a day, but after 1 week, not even one has sprouted. What should I do?
Answer: You shouldn't need to water them everyday unless you kitchen is very warm and the compost dries out. Remember, the surface may be dry but wet under the surface. Wet compost can cause the seeds to go mouldy and die. Compost only needs to be moist. It's a good idea to cover with a piece of card, plastic, glass or wood to stop the surface drying out. It's recommended to just press the seeds into the compost and they can take several weeks to germinate. Some strawberry seeds also need to be stratifieed or exposed to cold winter conditions to encourage them to germinate.
Have a look at this link.
Question: How do seeds grow?
Answer: Basically, a seed is like an embryo, the plant equivalent of a fertilised human egg, with genetic information from both parents. A seed is dormant in the absence of warmth and water, but once it's sown and detects moisture (it also needs oxygen and heat), it begins to metamorphosise into an adult plant. This involves using instructions in the DNA in its cells on how to grow roots, stems, leaves, and flowers.
Question: Is it ok to grow the seeds at home? How big should the container be? Should I leave it by the window with it open for some oxygen?
Answer: Yes, anyone can grow seeds at home, it's really easy.
The container size depends on how many seeds you want to sow. If you're going to sow lots as I did in the photo above, a tray, box or tin is best. If you only want to sow a few seeds, you can use a flower pot, yogurt carton, plastic cup, food container (wash it out first) or anything similar. Seed trays are usually about 1 1/2 inch / 40 mm deep, so seedlings need to be transplanted when they're tiny so that their roots have a chance to spread out and get bigger. If you use a deeper box, flower pot or container, you can allow the seedlings to get much bigger before transplanting.
You don't need to leave seeds near an open window to get oxygen! Oxygen is all around us. In fact, it makes up 19% of the air. And it'll also permeate down through the seed compost to reach the seeds. Seeds should be kept in a warm place at a temperature of at least 18 degrees C (64 F). Once they germinate, they need to be moved to a window, bright conservatory, etc. so they can grow properly. In dim light, seedlings rapidly become straggly as the stems grow long and thin as the plant searches for light.
Question: How deep should seeds be planted?
Answer: Tiny seeds can be sprinkled on the surface and not covered. It can help to press them down into the compost or spray with a mister after sowing. Larger seeds above about a mm (1/16") in size can be covered with a light sprinkling of compost. Much larger seeds, e.g. peas, beans, sunflower seeds etc can be pushed down about 6mm (1/4") below the surface of the compost if it's soft. In harder ground outdoors, you can use a stick or piece of rod to make a hole and drop the seed into it, or sow in drills which are slots made in the ground with a rake or pointed tool.
Question: When transplanting seedlings to thin them out, if they are tall and straggly do you plant them deeper into the new hole to stop them becoming too leggy?
Answer: No, it's better to keep the stem above the ground/compost or maybe slightly lower to cover any delicate roots, otherwise it can potentially be damaged by soil borne diseases. As the seedlings grow bigger, cover any exposed roots. It's important to expose young plants to light as early as possible to avoid them becoming straggly. If you're growing inside, get them as close as possible to a window or onto the sill and turn daily. Don't over water young seedlings. More plants are drowned by the roots being wet or killed by fungi in warm moist conditions than from drought. Compost should be slightly moist, not wet (stick your finger down into it to test, as it can dry out on the surface giving the appearance that it's dry throughout). Good ventilation is also important to avoid fungal diseases such as botrytis (grey mould).
Question: Do seed sowing instructions work for vegetables?
Answer: Yes, but some seeds don't like being transplanted, mostly root crop vegetables such as carrots, turnips, and parsnips. These can be sown directly into the ground. Pre-soaking hard seeds such as peas and beans for 12 hours, reduces the time needed for germination. Plants that have been started indoors should be gradually hardened off by placing them in the wind shaded spot, exposing them to outdoor conditions for a couple of hours a day, then taking them back inside at night. Extend the time gradually so that they become accustomed to lower temperatures.
Question: What is the proper depth for sowing seeds?
Answer: It depends on the size of the seed. Dust like seeds shouldn't be covered and sprinkled on the surface and kept moist. Seeds the size of grains of sugar should be covered with a fine sprinkling of a couple of mm of compost. Larger seeds, e.g., marigold seeds need about 5mm/1/4 inch of cover and very large seeds, e.g., beans need to be sown about 1/2 inches or 12 mm deep.
© 2014 Eugene Brennan
KikiKing on June 17, 2020: