top of page


Seed starting creates an earlier harvest!

WHY START SEEDS INDOORS? Seed starting has many benefits:

• The ability to grow long season crops in short season climates.

• Gaining a few weeks of growing time.

• Moving up the harvest date.

• An extra round of crops can be harvested before the summer heat arrives.

• A much wider range of plant varieties are available as seeds.

• Ensures high quality and healthier starts.

• The ability to raise the plants organically and chemical free.

• Reduces the cost of starting the garden for the season.

PLANNING: makes seed starting more efficient and successful. Almost every seed can be started indoors, and long season crops like eggplant, okra, tomatoes, broccoli, and kale, are favorites. Peas, beans, radishes, carrots, and corn perform best when they are direct seeded straight into the garden as they do not fare well when transplanted, or need to be transplanted at the right stage of growth so they aren’t stunted by stressors.

Things to consider before deciding to start seeds indoors:

• The amount of space available indoors to house the started seeds.

• The method(s) to be used to nurture the seeds as they grow indoors.

• There are enough transplants to adequately fill the garden plot.

• Determine where each crop of starts will be planted.

• Add a few extra seeds to account for things like seedling mortality.

• Check the seed packet for guidelines about when to start seeds indoors, germination information, days to maturity, and other growing tips.

• Understand the local climate such as a history of late and surprise frosts.

• Plan for pest prevention by using row covers, netting or fleece for bird protection, and slug traps.

WHEN TO START SEEDS: a general rule of thumb is to start seeds 6 weeks before the last local frost date, which is April 15th for the local area.

Always check the seed packet to verify the start date as some plants like basil, broccoli, cabbage, cauliflower, eggplant, lettuce, sage, Swiss chard, and tomatoes should be started 8 weeks before the local last frost.


• Seeds: seeds that are slow to germinate, need warm soil, or those that require a long season are all good choices for indoor starting. Flowers that are easy to start indoors include castor bean, coleus, marigold, and zinnia. Herbs and vegetables that are easy to start indoors include basil, broccoli, brussels sprouts, cauliflower, cabbage, eggplant, kale, bell, cayenne, and jalapeno peppers, and tomatoes.

• Seed Starting Mix: early plant nutrition is vital, and the right potting mix will provide the right nutrients that seeds need. The seedlings will spend their first crucial weeks in their starting cells, and they will need additional nutrition from compost or liquid fertilizer to protect them from diseases and pest infestations. If necessary, potting mix can be amended with compost by using 35% finished and not raw compost. Compost can be sourced from places like the local municipality, garden centers, or other gardeners, however, but be sure the compost doesn’t contain herbicide residues that can kill seedlings. For example, don’t use compost that’s been made from grass clippings that have been treated with broadleaf herbicides.

• Seed Starting Pots or Trays: container options for seed starting vary greatly and recycling and repurposing items like yogurt cups, sour cream containers, dixie cups, and egg cartons are good choices. The container should supply adequate drainage, so drill drainage holes if they aren’t present. A container also needs to hold its form through the entire seed starting process. Repeated watering can break down some transplant containers, and purchased or homemade paper containers are best suited for seeds that are only started a week or two before they are transplanted. Jiffy pots are a common container that works well and are compostable but lose some of their structure after repeated waterings.

• Humidity Dome: is an excellent tool to have, and when used properly, can help maintain soil moisture and temperature, increase germination rates, protect delicate or expensive seeds, and limit time spent watering seedlings. Seeds provided with moisture, warmth, and light at the right time will germinate. Humidity domes help maintain two of these three needs and are often used in conjunction with heat mats. They help protect the seeds, maintain moisture levels, and create the perfect environment for those seeds to get a great start. Using a humidity dome will increase germination rates significantly and decrease the time to sprouting for most seeds.

• Spray or Squirt Bottle: seedlings need to be kept moist but not wet and never allowed to dry out completely, which translates to watering them at least once per day, if not more often. A spray bottle is a good way to water seedlings and keep the soil moist without letting it get too wet.


• Seed Depth: the right depth is vital, and most seed packets will indicate the ideal depth. If this information isn’t available, a good rule of thumb is that the seed needs to be planted at a depth twice the diameter of the seed. Most seeds can simply be gently pressed into the mixture with a finger or the eraser end of a pencil.

• Sowing in a Pot: fill it to the brim with the potting mix, then tamp down to a firm level as seedlings prefer plenty of potting mix to sustain them.

• Sowing in a Plug Tray: fill it right to the top then tamp down to settle. Top up with a little more of the mix, then brush off the excess.

• Choosing Which Seeds to Plant: choose the largest and healthiest-looking seeds in the packet for the best chance at germination. Many vegetables, including common crops such as salads, onions, beets, peas, and radishes, may be sown in pinches of three to five seeds per plug for planting out as a cluster of seedlings which will later be thinned out. Larger seeds such as beans are sown individually into deeper holes made with a finger, pencil, or dibber which is a special seed-sowing tool. These need darkness to germinate.

• After Sowing: cover the seeds with potting mix so that they’re at the right depth as listed on the seed packet. Label the starts, especially different varieties of the same type of plant. This is important! Add the date of sowing and the variety sown.

• Water: the pots or trays carefully using a watering can fitted with a fine sprinkling hose or a clean turkey baster to prevent dislodging the seeds. A mist sprayer is gentle but can take a long time to get the mix properly saturated. Leave to drain through from the surface and then repeat. The mix needs to be really wet to wake the seeds from their slumber. It’s hard to overwater at this point provided a high-quality mix is used as any excess will just drain out of the bottom.

NURTURING SEEDS: indoor seedlings need the right conditions and environment in order to thrive:

• Temperature: look at the back of the seed packet to see what temperature the seeds need. As a general guideline, the optimal temperature for germination is often 5-10 degrees warmer than the optimal temperature for growth, with onions being an exception.

• Light: place seed containers in front of a window and rotate to encourage even plant growth.

• Supplemental Light Source: if natural light isn’t adequate, use an additional light source such as a grow light. The light needs to be close enough to the container so that the seedlings don’t get spindly, but adjustable, to accommodate the height of growing plants.

• Water: overwatering is more detrimental than underwatering. Check the plants once a day, before noon and at the same time every day, and water as needed.

• Humidity: cover watered plants with plastic domes to retain humidity. Remove the covering as soon as seeds have germinated and when there is green poking up from the soil to allow for good air flow.

• Fertilizer: use only as needed and typically four to six weeks after sowing if using a nutritive soil mix. If compost is used and there is sufficient soil in the pot, fertilizer isn’t needed as soon or as often as if a peat pot is used. Peat-based potting mixes don’t have as many nutrients. Don’t fertilize a plant that will be taken out in a week or so to harden off. A fish emulsion fertilizer can be used to meet organic growing requirements. Wait to fertilize until the plant is actively growing and fertilize at a low rate to avoid burning the plants.

• Heat Mat: is essential for seeds such as peppers, melons, and tomatoes that get a boost from bottom heat which helps establish the plants roots.

THE GERMINATION PROCESS: is the process of a seed sprouting and developing into a new plant. The process is highly variable, and most seeds will germinate within 3 weeks. If this hasn’t happened within three weeks, try starting a new round of seeds. Environmental conditions such as seed depth, water availability, and temperature trigger germination.

• Imbibition: water fills the seed.

• The water activates enzymes that begin the process of plant growth.

• The seed grows a root to access water underneath.

• The seed grows shoots that grow towards the surface.

• The shoots grow leaves to harvest energy from the sun.

• Photomorphogenesis: the leaves continue to grow towards the light source.

TRANSFERRING SEEDLINGS: if seedlings are grown all together in a tray, they will often need to be transferred or pricked out into their own pots once they have germinated. The best time to do this is once they have two pairs of leaves that contain a set of seedling leaves and the first set of true or adult leaves. It’s fine to move seedlings on a lot earlier than this as soon as they are big enough to handle. Don’t delay transferring the seedlings as they shouldn’t become overcrowded which can cause all sorts of issues such as leggy seedlings or disease. It’s also a lot easier to separate seedlings out when they’re small.

To Transfer Seedlings:

• Fill new pots with the same potting mix.

• Make holes then carefully remove the seedlings from their nursery pot.

• Separate the seedlings out, then transfer them to the waiting holes.

• Only ever handle seedlings by their leaves as if the fragile stem is damaged or crushed, the seedling won’t survive.

• Try to avoid damaging the roots as much as possible by bringing along as much of the potting mix that’s around the roots as possible. Working with really young and small seedlings is often better as they are quick-growing, and their roots are nowhere near as extensive as more established seedlings.

• Set seedlings a little deeper if they are a bit leggy to help support them and get them back on track.

• Firm in around seedlings.

• Gently water the seedlings with a watering can. Don’t worry too much if the seedlings get a little flattened, they’ll soon recover.

• Check the seedlings and plants regularly for soil moisture. Push a thumb into the potting mix or lift the pot up to gauge how heavy it is. The heavier it is, the more water it will contain and the less likely it is to need watering.

TROUBLESHOOTING: the growth phase after germination is when problems tend to arise, so keep a close eye on the plants, especially for these common issues:

• Pests: check growth points and the undersides of leaves while watering the seedlings. Be especially mindful of pests if houseplants are present.

• Damping Off: is caused by botrytis, a fungus that occurs if humidity exceeds 85%. The condition comes on suddenly and is initially seen as seedling collapse. The stem withers and the seedlings topple over. The problem isn’t reversible, but can be prevented by maintaining good air circulation, not over-watering, and ensuring the soil medium is sterile. If damping off occurs, remove the affected seedling as soon as possible and maybe even some of the surrounding soil.

• Leggy Plants & Spindly Growth: check the lighting situation, and if it has been particularly cloudy, supplemental lighting may be needed. High temperatures cause rapid growth and can also lead to leggy plants. Larger and older plants can also compete for light when they are close together, so space plants farther apart so that they don’t compete for resources.

• Poor Root Growth: poor drainage is one cause of poor root growth and can be prevented by using containers with adequate drainage. Too low temperatures, low fertility, and compacted soil can also lead to poor root growth. When potting, make sure the soil isn’t packed too tightly.

HARDENING OFF SEEDLINGS: seedlings of tender crops must be gradually introduced to outside conditions or hardened off before they are planted. Suddenly moving plants from a stable environment to one with wide variations in temperature, light, and wind can seriously weaken them.

• For most plants, start hardening off about 7 to 10 days before the final frost date for the area, withhold fertilizer, and water them less often.

• Seven to ten days before transplanting, set the seedlings outdoors in dappled shade for a short time, and make sure the spot is sheltered from winds. Start with an hour a day, then gradually extend the amount of time that plants are outside, until they’re staying out all day.

• Keep the soil moist at all times during this period. Dry air and spring breezes can result in rapid transpiration. If possible, transplant on overcast days or in the early morning, when the sun won’t be too harsh.

• Cool-season crops don’t really need as much hardening off, and crops such as lettuce, onions, beets, or peas can go straight outside as soon as the ground is ready when the soil is no longer cold and wet and has reached around 50ºF. Warm season crops such as tomatoes and peppers will need acclimatizing.

• A great way to toughen up plants whether indoors or under cover in a greenhouse or cold frame is to run the fingers lightly over the foliage. This mimics wind to create sturdier plants. Indoors a fan can be used for this purpose.

• If outdoor conditions allow plant seedlings out while they are still quite young as soon as 3 to 4 weeks after first sowing. Younger seedlings tend to establish quicker than those that have become root bound in their containers.

• If bringing the seedings back and forth from the outdoors is problematic, another option is to place them into a cold frame and gradually increase the amount of ventilation by opening vents progressively wider each day. Make sure to shut them down completely before dark.

7 views0 comments


bottom of page