Five Indoor Seed-Starting Tips from Margaret Roach’s A Way to Garden

Select Seeds Suited for Indoor Sowing and Transplanting

Many crops start well indoors–and need the extra growing time in a protected space while the weather is still too cold–but a few grow better when sown directly in the garden. There aren’t any no-break rules here. Even carrots can be transplanted, though it’s not generally recommended. Especially if you are trying a crop for the first time, read the seed packet for instructions on which method typically works best. Pay attention, too, to the days to maturity information and your crop’s cold tolerance to help decide where and when to sow.

Start with Good Materials

DSC_1656
Many seeds are viable for more than one year, but members of the onion family are notoriously short-lived. Pictured here, I sowed the far corner with fresh onion seeds and the near corner with seeds only 1 year-old. Barely any of the old seeds germinated.
  • Clean your seed-starting containers with a 1:9 bleach:water solution or soapy water.
  • Use a sterile grow medium formulated for seed-starting.
  • For best results, use fresh seeds. (See this link to a chart on seed viability and a great discussion on the difference between viability and vigor. More info here.)

Water Wisely

Keep your planting medium evenly moist until your seeds sprout, then let it dry out slightly between watering. In no instance should it be soggy or bone dry. Be gentle if you water on top and use a mister or similar method. Bottom watering avoids the problem of dislodging seeds and young transplants and helps prevent diseases.

Get the Light Right

This one is Margaret Roach’s most emphasized tip. Seedlings will need supplemental lighting–more than they’ll likely get on your windowsill–or they’ll grow tall and spindly.

For Perkins Park Gardeners: What to do if you don’t have a fancy grow light set up and still want to sow your own seeds for transplanting?

    • Try inexpensive shop lights. I’ve had reasonable success growing seedlings with a couple of shop lights purchased for around $15 at Ocean State.
    • Squeeze one or two cell packs on your windowsill and supplement with a simple clamp light fixture (bulb separate). Set them outside on warm-enough days, taking care to harden them off (see next tip) along the way.
      DSC_1682
      Lettuce seedlings grown on a windowsill get a little long and floppy, but do all right if you don’t have to hold them long indoors.
      DSC_1685
      But seedlings quickly dry out and outgrow their small egg carton confines.

      DSC_1686
      Here’s another windowsill setup, fashioned out of a recycled cell pack and a milk carton, that gives seedling roots more room to grow.

Take Time to Transplant with Care

Harden off plants before you transplant them to their final space in the garden. They’ll need to gradually acclimate to outdoor conditions, especially to the sun. Start with no more than 1 hour outside in direct sun on the first day (not midday) and gradually increase the time of outdoor exposure over the course of about a week. You’ll know you’ve overdone it if you see bleached or brown and crispy patches on your plants’ leaves. Alternatively, some people like to choose overcast days, leaving them outside during daytime hours for a few days.

Once you’ve gotten your plants hardened off, make sure you’re not rushing to get your plant in the garden too early, before you are reasonably clear of of unsuitable weather.


For more seed-starting tips (and more):

A Way to Garden by Margaret Roach (2019).

For a wide range of seed-starting information see Margaret Roach’s website.

 

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