DIY Indoor Greenhouse: Moving Day!: Hardening Off Seedlings

I call this a success!

I hope you are having as much success with your DIY Indoor Greenhouse as I am with mine!  For a minimal investment,
much of it salvaged or collected throughout the year, I will be transplanting my best crop of seedlings ever.  After much loving care, it's time to start moving some of the seedlings out of the greenhouse and into the real world.  Sort of.

While many of the tomato varieties have thrived in the tropical conditions so much that they have grown into the lights, they cannot go from the controlled conditions of the greenhouse directly into the garden.  This transitional period is called "hardening off."

The first issue is the temperature variations:  from the mid-30s to the low 80s within the past six days.  Tropical seedlings like tomatoes and peppers just do not like temperatures under 60.

A greenhouse allows you to create ideal conditions for your seedlings.

The second issue is the humidity.  While summers are quite sultry here, this spring has seen low humidity in between torrential downpours--which is another reason to harden off the small plants.  They need to be a little more sturdy before they have to stand up to a heavy rainstorm.

A third issue is variation in water levels.  In the greenhouse, I water from the bottom and occasional mist to maintain humidity and to prevent the seedling mixture from drying out on top.  Watering from the tray rather than the top causes the plant's roots to develop deeply to seek water rather than bunching around the surface.  This will benefit them later in the summer when rain is scarce.

Don't let your babies become sunburned!

A fourth issue in hardening off is variable light levels.  The greenhouse is lit 18 hours a day, using fluorescent tubes from two spectra.  While bright, the light is not nearly as harsh as the sun, so they young plants need gradual exposure to the sun before plopping them into the ground.  I forgot about that and put my little leafy friends in the sun for a day or two.  The leaves began to brown before I recognized the symptoms of sunscald (think of it as sunburn for plants).  Immediately I moved them to a deep covered porch where they receive direct morning sunlight for about four hours and indirect after.  They are much happier there.

Looks bare, doesn't it?

So, the greenhouse looked a bit bare, for a few days, at least, until I started more cabbage and spinach and replanted peppers which had not sprouted.  I'm already looking forward to starting my fall "crop"!

I will make one big change, though, before next winter.  Some things (like peppers and eggplant) just like warm soil.  I'm planning to add some level of temperature control like seedling heat mats.  I'm already watching my usual sources to catch them on sale!

And one investment has yielded wonderful results!  This year I invested in deep inserts for 1020 trays for seed starting.  I'm a lazy gardener, so I sow seeds directly into the trays from which I will transplant rather than into starting flats.  The inserts are 1" deeper than traditional inserts and the tomatoes, especially, are several inches taller than comparable varieties planted in the shallower inserts.  The cost differential ($.10 more per sheet) is negligible for the increased plant size.

Well, the weatherman says it will cool to 50 degrees tonight, so I must go move my plants (on a rolling cart) into the garage for warmth.

What about your seed starting adventures?  Any advice?  Any funny stories?

What's growing in your Savory garden?

Nancy