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garden:cultivate:tasks:propagate:starting

Starting seeds

Seedling mix

A half-inch sieve for breaking up the clumps of the seeding mixI'm using Sungro 3 organic seedling mix from Steuber's Distributing in Snohomish as the medium for planting seeds.


Seeded cells in the larger pansSo I'll remember next year, here's the procedure:

  • I break up any clumps by sifting the mix through my half-inch sieve.
  • The mix may be dry so I add a little water.
  • I fill a small tray or six-pack with the mix and pack it down just a bit.
  • I add a number of seeds depending on the size and how many plants I think I need.
  • I add water to the 10“ x 20” tray and sit the filled cells in it.
  • I put a clear cover over the top to keep in moisture.
  • I put the tray on a heat mat connected to a temperature controller set to the correct temperature.

Propagation heat mats

Two independent propagation areasI have two propagation stations so I can germinate seeds at two different temperatures, most seeds at 70 degrees, the seeds for heat-loving plants (tomato, pepper and egg plant) at a warmer temperature, around 80 degrees.

Vegetable seeds don't need light for propagation, but when days are cool I keep the grow lights on as an extra heat source. The heat mats are limited output and keep the cells at a maximum of 15-20 degrees higher than the ambient temperature.

The propagation heat mats are of two sizes:

  • One 20“ x 44” for the primary station
  • Two 20“ x 22” mats for a secondary station

With this setup I can have 8 trays propagating at a time.

"Heat" mats

I set a heat mat controller for a desired temperature for the related seeds, from 65 degrees to 80 degrees.

The temperature setting on the heat mat controller is a maximum, not an actual temperature in the tray under all conditions. When the ambient temperature is considerably lower than the setting, the tray temperature is unlikely to reach 10 degrees above the ambient temperature.

Two temperature controllers

A heat mat controller turns off power to a mat when its sensor registers higher than the set temperature.

I have two temperature controllers. Depending on the number of plants I have at each temperature, I may hook the large mat and a small one to one controller and the other small mat to the other controller. Or I may have two equal areas at the two different temperatures. I like the flexibility.

After germination

After the seedlings are up, I remove the clear covers and I leave the grow lights on for at least 10 hours a day. I have the lights about 7 inches above the tops of the seedlings.

A schedule in a home automation computer in the house turns the grow lights on and off.

It's also at this time that I have an oscillating fan blowing air. This is a prelude to hardening off as well as a way to preclude development of bad fungi and bacteria.

I let them grow, looking for the first set of true leaves.

Special handling

For details about propagating cool-weather plants see Cool-weather plants.

For details about propagating heat-loving plants see Heat-loving plants.

garden/cultivate/tasks/propagate/starting.txt · Last modified: 2020/06/15 23:02 by davidbac