Starting seeds indoors

Many plants must be started indoors, in order to do well in our relatively short summers. They should be planted by start dates specific to individual plants. This information can be found on individual seed packets, as well as in the seeding date section.

With Calgary's short growing season, plants grown from seed often do not have the proper conditions to complete their cycle of growth. Many seeds get off to a better start when they are sown indoors in containers and later transplanted outdoors. Many would not have the time to flower unless planted much sooner than is possible outdoors.

  Plastic flats are the perfect containers for starting seeds, but any container with adequate drainage will do. Seeds that are started in February or March will do much better growing under fluorescent lights, as day length is short and windows do not provide light over a long enough period. Those started in April and early May will generally be fine in bright, sunny windows. Some seeds need heat to germinate, some need cool; some need to be covered, and some need to be exposed to light. Experiment with likely spots in your home and remember that fluorescent lighting can be added to supplement natural light.

Seed planting steps (indoors)

  1. 1) Plants seed in flat or other container at depth indicated. Peat pellets are also ideal for starting seedlings.
  2. 2) Water well and keep moist but not too wet.
  3. 3) Thin plants as necessary.
  4. 4) Some may have to be transplanted into slightly larger, separate containers and allowed to continue growing before planting outdoors.

Seed-starting happens in two stages: Germination and growing.

Germination is the sprouting stage when the embryo of the plant emerges from the seed. You won't generally need light at this stage, but you will need a spot that has gentle warmth which of course lights can provide. If you don't have lights provide gentle heat by setting the containers on top of a refrigerator or dryer; by propping them a few inches above a radiator; or by using special heating mats sold for this purpose. Oxygen is crucial to the germination process, so you want to keep your soil moist, but not wet!

As seedlings break through to the soil surface, they are quickly running out of fuel from the seed and need a new energy source, this is where your light comes in. If they don't get enough light, they are more susceptible to attack by fungi. Window light is usually too weak and directional especially if you are starting vegetables. Vegetables should have a bright overhead light.

seedlings sprouting

Once you see green sprouts about half an inch tall, you will move your plants under the lights in a cooler environment about comfortable room temperature, between 15 and 21 degrees. A cold garage won't do; neither will a broiling furnace room. Now you'll want to uncover the containers, or at the very least open the vents on the cover to maximum if your seed tray covers have them and water your seedlings from the bottom, by pouring water into the tray. Never water the seed-starting mix or pellet from the top as it courts disease especially a fungus disease called "damping off" and heavy watering from the top may actually dislodge or damage the sprouts. Remember they're just babies! Also ensure air circulates freely, so humidity isn't trapped around plants.

A seedling's first set of leaves is followed by a lull in the action as the seedling switches its power source, develops its first true leaf, or two and grows a flurry of new roots. Crowded seedlings can be separated and re-potted when the first true leaf appears. Only transplant if necessary. If you are transplanting the seedlings must recover from only one stress at a time. So, immediately put them back under the lights. At their next watering, the transplanted seedlings can have a heavier than normal watering with lukewarm water to eliminate hidden air pockets. Always drain off the excess. If the potting medium settles, you can sprinkle more dry mix around the base of the seedling to help keep it upright.

Any nutrients present in the seed-starting mix will be gone after about three weeks, so your seedlings will need supplemental feeding as they grow up. To feed the seedlings try a liquid fertilizer mixed at the rate recommended on the package for seedlings. They will still be fairly tiny, so don't overdo it with the fertilizer you can kill them with kindness by burning their tender little roots. You just need enough to keep them happy.



As the seedlings grow, use a mister or a small watering can to keep the soil moist but not soggy. Let the soil dry slightly between watering. Set up a fan to ensure good air movement to help prevent disease. You can use a fan that's plugged into the same timer as your grow lights which just makes things easy.

You'll need to check your seedling almost daily to ensure lights and fans are running and that they don't completely dry out! It doesn't take them long to crater if the soil or pellets go bone dry. Again, if they are in a window you will want to turn the seedling regularly, so they are not always stretching to the light.

Once you have spent a few winter weeks gardening try and remember it's not a good idea to move your seedlings directly from the protected environment of your home into the garden. You've been coddling these seedlings since the day they were born, so they need a gradual transition to the great outdoors. This process is called hardening off. About a week before you plan to set the seedlings into the garden, place them in a protected spot outdoors that's partly shaded and out of the wind for a few hours daily, bringing them in at night. Gradually, over the course of a week or 10 days, expose them to more sunshine and more wind. If you have a cold frame this is a great way to harden them off. You will know when it's time to plant when you are certain the risk of frost has passed.

seedlings in Jiffy Pellets

To avoid total heartbreak when transplanting to the garden ensure you use a higher middle number fertilizer like 10-52-10 or Myke this will help with transplant shock and ensure that they don't have issues during this final step.

There is something magical about starting seeds at home and that magic is transferred to your garden and its something you will be proud of even if you have some failures. One thing is or sure, once you have started seeds at home you will want to do better every year, so keep your notes in a safe place and rejoice when winter arrives. Sooner than most you'll be gardening again but this time you will be armed with a little more information and experience and with that, you will be adding to your gardening prowess exponentially!


Hardening off

Seedlings grown indoors or in a greenhouse will need to be hardened off.

Hardening off is the process of adapting a seedling grown indoors to the outdoors over the course of a couple of weeks. Differences in temperature and light intensity may set back plants and delay flowering if the plants are not gradually acclimated to both.

To start, plants should be kept in a sheltered area away from intense sun and harsh winds. A cold frame is an excellent place to harden off your seedlings but any sheltered spot will work well. Plants should be covered or brought inside at night if temperature or wind conditions dictate. Over the course of two weeks, gradually increase the plants' exposure to the sun's intensity and other elements. At this point, seedlings can be planted outside in beds or rows whenever weather will permit.

Planting seedlings

For instant results, or a quick start for plants that need more time to complete their life cycle than Calgary's climate allows, seedlings are the perfect fit. They can instantly add greenery and colour to your beds.

In Calgary, spring frosts can last until late May. For that reason many area gardeners wait until at least June 1 to plant their seedlings outdoors.

Note: For best results, do not plant your seedlings during the heat of a sunny day. This may cause undue stress on seedlings. Planting seedlings on overcast days or in the early evening will help greatly to reduce this stress.

Steps for planting seedlings

  1. Plan area to be planted.
  2. Work and condition soil
  3. Dig a hole that will accommodate the seedling you wish to plant.
  4. Remove seedling from its flat or pot. Massage root ball gently. Separated roots will reach out for moisture or nutrients.
  5. Set plant in hole and add soil until the seedling is planted at the same level as it was in its container.
  6. Firm down soil around the seedling and water in well.
  7. Fertilize the plant with transplant fertilizer (5-15-5) to help prevent transplant shock.

Note: Tomato seedlings should be planted deeper than other seedlings, usually up to their first set of leaves.

Note: Peat pots should always be removed since they do not degrade well in Calgary's short summer and often dry climate.