Seed Starting - Wenatchee River Institute

E. Lorene Young
Community Garden
2013 Gardening
Workshop Series
Seed Starting
In cooperation with: Wenatchee River Institute and
Chelan County Master Gardeners
Welcome!
Why Start Seeds Indoors?
 Some plants take a long time to mature and will not
produce in Northern climates unless started early
 Hedge your bets against adverse weather during the
seedling stage
 Expensive seed (particularly flowers) can be sown under
a more controlled environment to increase chance of
success
 Tiny seed can be more carefully planted indoors than
direct sown
Goals for this class:
 An understanding of the terminology and equipment
involved in the process of seed starting
 Requirements needed by the seed for good germination
 Timing for seed starting and transplant options
 Introduction to the greenhouse-common pests
Seed Quality
Quality seed is important. Older seed will have
decreased germination. Test germination by placing 10
seeds between a layer of two damp paper towels. Look to
see how many seeds sprout. This will give you an idea of
the % viability. Adjust sowing rate accordingly.
 Store seed in the freezer or fridge for long-term viability
Temperature Ranges for
Seed Starting
 Germination is very temperature and moisture specific.
 Johnny’s Seeds Catalog- visual table of germination
temperature ranges; excellent reference for seed starters
Temperature Ranges for
Seed Starting
If the temperature is:
 Too Cold-Seeds succumb to rot
 Too Hot- Seeds succumb to rot
Outer edges of ideal germination temperature
leads to spotty germination. Approximately 50%
of seed will not germinate.
Correct temperature and moisture will lead to 85100% germination
Spotty
Germination
Equipment-Heat Mats
 Heat Mats- thin, flat, waterproof plastic mat filled with
heated wire. Plugs into any standard outlet.
 Available Sizes 1 Tray, 2 Tray, 4 Tray, 4 Tray linkable
 Multiple mats can be attached to a thermostat
 Typically raises soil temperature up to 10F-20F above
ambient (more or less, dependent on ambient temp)
 Directed heat at the root zone
 Efficient and cost effective- can be used as a substitute for
a heated structure
 Can be put on a thermostat and timer if required
Windowsill heat
mat-3”x20”
Thermostat for
heat mat
Bottom Heat-Other Options
 Heat cables- rubber coated cables that can be buried
under soil or attached to a structure. Tend to cause more
problems and burn out sooner than heat mats
 Heat Table- fabricated from re-cycled refrigeration radiator
attached to small water heater and circulation pump
 The top of the refrigerator or stand up deep freezerconditions similar to a heat mat w/o the thermostat control
Heat cables
under
burlap-
Buried heat
cables in
raised bed –
Beware
heat
damage to
surfaces
Beware of
shovels!
Temperature Ranges for
Seed Starting
 Warm Soil Germinators (77-86F)- Basil, Tomatoes,
Peppers, Eggplant, Summer Squash, Melons,
Cucumbers, Coleus
 Cool Soil Germinators (65-77F)-Brassicas (broccoli,
kale), Lettuce, Alliums (onions, chives, leeks), Mustards,
Asian Greens
 If you cannot control your heat, 75F is a good all around
temperature for most seed germination.
Lights
The purpose of additional lighting is to:
 Stimulate germination
 Eliminate stretching and weakening of
stem
 Aid in photosynthesis (food production)
 Side benefit of additional warmth with
larger bulb wattage
Lights-High Pressure Sodium
 Offers a wide color-temperature spectrum and is energy
efficient
 Same type of bulb as street lights
 Emit a yellow-orange color light. This spectrum reflects the
shorter day months of the fall and winter, where the sun
remains lower in the horizon for the duration of the season.
 Red spectrum light may trigger a greater flowering response
in plants. If high pressure sodium lights are used for the
vegetative phase, plants grow slightly more quickly, but will
have longer internodes, and may be longer overall
(stretching).
Lights-Metal Halide
 Emit a blue spectrum of light and are a good
representation of spring and summer sunlight filled with
bright blue skies.
 Are sometimes used for the first (or vegetative) phase of
growth as they have some blue light; however, they
have peak intensity around yellow spectrum.
 Blue spectrum light may trigger a greater vegetative
response in plants. Compact, dense vegetative growth
vs. flowering response.
Additional Lighting Equipment for
HPS and MH Bulbs
 The light is often fitted within a reflector to direct the
light downward.
 An electrical ballast is used to step-up the voltage and
adjust the current to power the bulb. Works with 120 V
household power source. Some ballasts are adjustable
and can work with a variety of wattages of bulbs.
 Motorized light movers allow one bulb to cover up to 23xs the area. 1-400W bulb can adequately light a 4’x8’
surface.
reflector
ballast
Light
Mover
Specs for HPS and MH Bulbs
 Most common bulbs are available as 250 Watt, 400
Watt, 1000 Watt. Can be used as a replacement to
natural light or as a supplement.
 Bulbs are twice as efficient as Fluorescent Tubes; a 400
Watt bulb can emit as much light as 800 Watts of
Fluorescent tubing
 High heat output. May require circulation fan (box fan)
or use in an unheated space. Lights should be at least
18” above plants
 High initial investment cost, but long equipment life.
Lights-Fluorescent Tubes
 Economical choice for home gardeners.
 Available in cool, warm and full spectrum bulbs
 A supplement to natural light, rather than a
replacement; limits what you are able to grow
 Low heat output; can be near soil surface and raised as
needed if mounted on chains or pulleys
Light Requirements for
Germination
 Seed packet should mention light requirements
 High Light requirement= surface sown. Do not cover
with soil but tamp in seed for good soil contact. Requires
diligence in maintaining surface moisture (misting)
 Otherwise, seed should be buried to a depth no more
than 2xs the size of the seed (approx ¼” for most
seeds)
 A sugar sifter can be used to apply a thin layer of
sand/peat over top of seed for consistent thin coveringthis gives the emerging roots something to grab on to as
the seed twists and turns during emergence
Soil Mixes –Top Soil
 Top Soil-non-sterile medium typically containing sand,
silt, clay and some organic material
 Can be sterilized in the oven (130F) but is often too dense
for seed starting
 Composted bark, often sold as ‘top soil’ is not suitable for
seed starting due to high percentage of tannins (tannic
acid)
Soil Mixes
 Pre-Made Potting Soil-sterile medium with good
drainage and some water retention
 Ingredients typically include pearlite for drainage,
vermiculite for water retention and drainage, peat moss
for water retention
 Generally low amounts of food immediately available.
Requires addition of nutrients once seedlings develop
true leaves
 Compost-non-sterile source of slow release nutrients
and organic matter for improved soil tilth
 Not always appropriate for seed starting due to potential
presence of vectors (cold pile compost) and the tie up of
Nitrogen from incomplete decomposition of woody
material
 Can be used in a 1 to 3 ratio with peat moss if of good
quality
Amendments
Amendments- items added to potting soil to modify pH,
add structure or offer nutrition to the plant
 Blood Meal; Source-slaughter operations. Kiln dried
blood- slow release Nitrogen
 Rock Phosphate; Source-Mined. Slow release
Phosphorus
 Kelp Powder; Source-Ocean Farming/Harvest. Slow
release micronutrients iron, copper, zinc,
molybdenum, boron, manganese, and cobalt.
Contains macro nutriend potassium. 70 different
minerals, growth hormones and enzymes plants need
for development