Starting and Troubleshooting Your Seedlings by Jan Boone

For those of us that garden at 5,280 feet and above, every year it’s easy to get frustrated and discouraged by the unexpected failures of starting our own seedlings. This is especially true after putting in every effort and the time to check various growing calendars, secure the right seed variety for your garden conditions and ensure your indoor growing area is all set to go.  Be it heirloom seed for your vegetable beds or flower seed for the pollinators, it’s sometimes a real challenge  to figure out what’s really going on and what one needs to accommodate our short growing season. All the work gets done and suddenly after a few weeks of watching tiny green sprouts germinate to the surface, you’re met with thin stems that seemingly grew 2” overnight, thus forcing the seedling to fall over, or a tiny insect has somehow invaded your soil medium and nothing looks right.  It’s the dreaded soil fungus fly!

Here are a few essential pieces of information for successful seed starting and growing that you can  keep in mind:

Soil  For indoor seed starting, a commercial soilless medium is easiest to use.  Most contain peat and perlite.  There is a balance to achieve of good drainage and enough moisture retention to allow the seed to germinate.  While there are also recipes online for making your own mixture, beware of contaminants and suggested compost or fertilizer additives.  Save the garden soil for direct sowing of seed after you’ve done your prep work in the beds.

Water – The essential element to allow germination!  Work to keep your soil medium moderately and evenly moist every day.  Consider bottom watering from a tray and even saturating the medium the night before you plant your containers or trays. Too much water saturates the soil, decreasing aeration, thus potentially hampering root growth and causing damping off.  Too little water will likely impede growth or stop it all together.

Light – Indoor grow lights improve your chances of success.  Most have a color range from blue to warm.  Look for a bulb simulating the closest thing to natural daylight – usually 5,000-5600K.  Guidelines vary somewhat, but most seedlings require 14-18 hrs of light daily to germinate.  Consult your seed information.  There are variances for different vegetables as well as flowers.

Temperature – This is often the hidden challenge for many, particularly those just starting to grow seedlings.  For our average vegetables and plants, seeds will germinate at an optimum soil temperature of 68-80 degrees.  Invest in a soil temperature gauge (or an oven roasting thermometer) and a heat mat to help control this.  The trick is achieving the happy medium of soil temperature to optimal air (growing) temperature.  Soil medium can be several degrees cooler than air temperature just due to evaporation.  You don’t want to wait so long that our short growing season hampers fruit production or causes late leaf maturity causing bitter tastes or late bolting.

Red Flag Warnings –

·         Leggy & spindly seedlings or plants – Usually caused by not enough light, excessive water, seeds too close together, temperature too high or old seeds.

·         Rotting or collapse of stem at soil – Damping off, frequently caused by too much water in soil or medium. Invites soil fungus which invites insects.

·         “Bleached’ or yellowed upper leaves – The light source is too close to seedlings.

·         Seed Coat adheres to seedling leaf (cotyledon) – Low seed viability, old seed.

·         Yellowing leaves close to soil – Possible sign of soil depletion if no insects are present.  Consider

A nitrogen based fertilizer (20-20-20) in a small application.

If you’ve made it this far and your seedlings have survived with leaves around the 2” mark, you’ve made it past the obstacles mentioned above.  Congratulations!  You are now ready to harden off your seedlings and transplant them into your garden beds.  Watch for future posts covering these steps.  You can also refer to the Colorado State University Extension website for further information on seed starting and transplanting.  Happy spring- our garden work is just beginning!