All About Seeds

On Friday February 25, 2011 I attended a very enlightening presentation called “All About Seeds”, presented by the  Calgary Horticultural Society and the Unitarian Church of Calgary’s Green Sanctuary.  It was a very interesting evening with three lovely ladies speaking about different aspects of gardening directly from seed: indoor seed starting, seed harvesting, and winter sowing.  Each is summarized below in sections below the fold.

Indoor Seed Starting

This is probably the one thing all gardeners think about at some point in their career, be it as a fresh novice or an experienced veteran.  However, the impression I get is that indoor seed starting is not for everyone.  That said, there are several advantages to starting seeds indoors.

  1. Cost – seeds are much less expensive than purchasing seedlings at a garden centre
  2. Quality –  when done right, plants started indoors are generally hardier and of better quality than those purchased at a garden centre
  3. Variety – seeds can be purchased in a much wider variety than is available from nursaries and garden centres; it is also much easier to get those hard-to-find plants

For example, alpine strawberryAlpine Strawberries seeds can be purchased for as little as $3.29 for 700 seeds.  A single seedling in a four-inch pot would cost around $4.00 at a garden centre.  I think I know which one I would prefer.

To Consider…

Now, there are several factors to consider when deciding what to purchase and plant, but most of all you must consider propagation and sourcing.

Propagation refers to how the plant is pollinated and propagated.  Basically, heirloom seeds are open-pollinated while hybrids cross-pollinate.  Heirloom seeds are called such because they are collected, grown, harvested, and passed down through generations.  The ideal is a preserved, pure strain, since the seeds produce seedlings identical to the parent plant.  These seeds are often found through seed catalogues, garden clubs, seed trading groups, and seedy Saturdays.  Hybrids, on the other hand, do not necessarily produce seedlings identical to the parent.  In fact, it rarely happens.  You can take seeds from a particular petunia, but it is unlikely that they will germinate and produce the same particular pattern – indeed, the colours could be completely different.

There are many ways and places to get seeds:

  • retail (garden centres, etc)
  • mail-order catalogues
  • seed swapping events (such as Seedy Saturdays)
  • friends
  • gardening clubs/groups

It is important to remember to check, especially when using mail-order catalogues, the number of seeds per package, delivery charges (may be flat rate or by packages, etc), and for any promotional deadlines.  Possibly the best thing about mail-order catalogues is the sheer variety of seeds available – far more than what you will find most anywhere else.

One other point to be aware of, however, is the proliferation of Monsanto seeds.  Many mail-order companies stock these seeds, but it can be difficult (at best) to pick them out without a little research.  I don’t want to get into all the issues with Monsanto here, but suffice it to say I think they’re bad.

Last Frost?

In Calgary, average last frost date is May 23.  We do not get more than 12 hours of sunlight until after the Vernal equinox (March 20/21).


Of course, some supplies  are required for any kind of gardening.  This goes equally for indoor seed starting.  At  the very least, you will need:

  • seeding trays
    • make sure to clean with chlorine bleach and rinse thoroughly
    • make sure you have room (1 seed tray of 72 cells transplants to 4 trays of 4″ pots)
  • growing media: several options are available
    • soilless (ProMix BX has a good balance of ingredients to allow water retention and drainage)
    • peat pellets are not great, and coco coir has no nutrient value and may contain residue from processing
    • use a sharp drainage medium (cactus soil) for succulents such as rosemary
    • eco-friendly sowing pots
    • cow pots (made from cow manure)
  • labels
    • make sure to label everything at the time of sowing
    • use a marker or paint pen that will not wash off
    • use labels that will not fade or deteriorate with humidity or sunlight
    • old venetian blinds work wonderfully
    • wooden popsicle sticks will mould and decay
  • sunny window(s)
    • make sure to clean the window(s) first
    • choose seeds with recommended sowing at most 4-6 weeks before last frost
    • south-facing windows will provide the greatest light
    • turn trays daily
    • be aware of high-efficiency windows that block more high-energy light from reaching plants
    • be aware of drafts and temperature fluctuations that may affect germination
  • temperature control
    • not required, but may be helpful
    • Stokes Seeds catalogue is an excellent reference for optimal germination temperatures
    • bottom heat (heating mats) can make a significant difference for consistent germination – just be sure not to put the heating pad(s) on a timer

Four things that can make a significant difference are

  • heating mat(s)
  • plastic dome(s) – remove dome when first set of true leaves emerge
  • oscillating fan – air movement can help prevent many different diseases
  • lights – no more than 2-4″ from plant material (seedlings become “leggy” if light is too far); keep light on 15 hours per day

Indoor Sowing Steps

There are six basic steps for sowing indoors:

  1. check and prepare seeds
  2. put soil in a bucket; allow to sit for about 15 minutes; mix
  3. fill containers 3/4 full and gently tamp; add more and gently tamp
  4. use a pencil (or other tool) to make holes to recommended depth
  5. mist surface with warm water and cover with clear plastic or dome
  6. label each variety!

When you can see roots escaping through bottom drain holes, it is time to transplant to a larger pot.  Bottom watering is best: let the tray(s) sit in 1″ of warm water for about 15 minutes.

Hardening Off

Plants started indoors are sheltered from wind  and cold temperatures, and shaded from sun.  Therefore they must be eased into an outdoor environment.  Place seedlings in a sheltered location for the first week.  If temperatures dip below 5 °C you may need to bring them inside.  Direct sunlight will be harsh at first, the wind will whip the seedlings, and the temperature will be cooler than inside.  Allowing controled exposure will allow the plant to strengthen gradually.

Keep your seeded area free of weeds.


There are countless resources and books available online and in bookstores.  Here are four that are recommended.


I will cover seed harvesting and winter sowing in the next article.

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