How to Germinate Seeds: 3 Effective Methods

Dormant seeds in a seed packet can be germinated in many ways. In this article, I'll cover three methods to germinate seeds quickly. View the videos or written instructions below for a quick guide to each of the seed starting methods I have used successfully.

The 10X20 Out of the Box Heat Mat Option

This seed starting method is the simplest. You just buy a heat mat that comes sized for a single 10X20 seedling tray and you plug it in. Unlike my other seed starting methods, you can't adjust the temperature to optimize the specific soil germination temperature of the crop you are growing, but these heat mats generally keep most seeds in a decent germination temperature zone. Here is the cheap seed starting heat mat I bought but there are lots of heat mat options available online in the $10-30 range.

The Sand and Heating Cable Seed Propagation Bench

Seedling Propagation Bench DIY Project Overview:

An excellent large scale seed flat propagation bench can be constructed using sand and de-icing cable or soil warming cable. The design uses a a cheap temperature regulated outlet shut off connected to de-icing cable or soil warming cable to provide the heat to raise soil temperature to accelerate germination, and a layer of moist sand evenly distributes the heat to all seed flat cells and

Seedling Propagation Bench DIY Project Steps

1.) Build or an acquire a box that is the size you want. This will depend on the number of seed flats you want to be able to germinate. I built mine 2 foot by 4 foot out of scrap 2X6s

2.) Insulate the bottom of the box to avoid heat loss as you are warming the soil. I cut a piece of rigid foam insulation to cover the bottom of my box.

3.) Cover the bottom of the box with something water proof to protect your insulation, floor, etc. from getting wet when you are watering the seeds/seedlings. I used 5 or 7 mil panda-film for mine.

4.) Carefully snake de-icing or soil warming cable back and forth on the bottom of your waterproofed box and tape it down in such a way that no cable is touching any other cable (to prevent inadvertent short circuits or excessive heat in any one location.) I used de-icing cable and duct tape.

5.) Fill the box with 2 inches or so of sand. Moisten the sand.

6.) Set your seed flats into moist sand.

7.) Plug the de-icing or soil warming cable into the temperature regulated outlet and plug the temperature regulated outlet into the wall. Place the soil probe on the temperature regulating thermostat into a cell on the seed flat. Set the soil thermostat to the correct germination chamber. Soil germination temperatures suggested for different seedlings based on germination rate and speed to emergence can be found here. I've also include an image containing similar seedling germination temperature data at the bottom of this page.

8.) Water or mist your seedlings regularly

9.) If you are going to be leaving them on the propagation bench after they germinate, be sure to put the bench in a sunny location. Otherwise, the seedlings will become leggy. Light is typically not needed to germinate seeds, but as soon as they emerge they will need light, so monitor seed emergence closely.

DIY Water Bath Germination Chamber

Water Bath Germination Chamber Overview:

The water bath germination chamber is the method I like the best because it doesn't require watering the seed flats and it can be tuned fairly precisely to the specific seeds you are trying to sprout. Basically it involves heating a mass of water to a certain temperature and using an automated aquarium heater to keep the water temperature there. I built mine for a total of less than 15 bucks.

Steps to building a DIY water bath germination chamber:

1.) Get a water tight container that will be tolerant to the water temperature you need to maintain for the seeds you are trying to germinate.

2.) Buy an aquarium heater with an adjustable thermostat. This is the cheap heater I used one I used to heat my water bath.

3.) Set the heater into the water and attach to the bottom of your container. Ensure the element is entirely covered by water

4.) Use something to create a platform that you can set your seed flats on. I used two bricks, but you could use any kind of water tolerant rack. For more commercial water bath germination chambers, folks will often use old refrigerators with buckets of water in the bottom.

5.) Set your seed flats on top of the platform you have created. If you set them so their bottom half inch or so is just resting in the water bath, the seed plugs will be both heated and bottom watered by the water bath.

6.) To increase germination percentage and speed, you can use a lid on the container. This will increase moisture for the seeds as well as ensuring a more even soil temperature and decreasing energy loss and evaporation.

7.) If you do cover your seed flats or you do have them in a dark place, you need to ensure the seedlings are brought into the light as soon as they emerge. This can be done through providing an artificial grow lamp, or it can be done by moving them to an outside location under some greenhouse plastic using a DIY Cold frame like I made in this video.