Germination Tips

Cucumber seedlings are just starting to pop out of the soil.

This is one of my personal favourite departments in gardening! The potential contained within each dried-up little dormant seed astounds me, and I delight in observing how different seeds germinate and grow as they get ready to eventually find their home in the soil (hopefully, unless you have too many seedlings, then you may have a problem!).

Understanding the needs of each seed will help you achieve quick germination that will create strong seedlings that have a better chance of thriving in the garden.

The 2 main needs of a seed to germinate are constant moisture and the correct temperature. Some seeds have particular lighting needs (some need light: lettuce, dill, parsley and then some need dark: cilantro, larkspur, calendula, nasturtium) or to be scarified (seed coat damaged) or stratified (tricked into thinking it went through winter) but most aren’t particular either way as long as they have moisture and the correct temperature. For example: in the spring, you want to wait to plant bean seeds until the soil has warmed up; otherwise, they will rot in the soil rather than germinate. Sometimes trying to be early doesn’t get you ahead; it can actually get you behind.

Investing in a heat mat, clear lids and a good hand-held mister is a good start if you want to grow seedlings out and even better if you can figure out a way to supplement light for the seedlings as they grow. Shop lights (fluorescent lights) are a cheap and easy way to produce healthy seedlings; I have never used grow lights (even at ALM Farm) and have had good success growing a wide variety of healthy seedlings, including tomatoes, peppers and cucumbers using only fluorescent bulbs. You can get hot and cold spectrum bulbs, so if possible, mix those up, but it’s not necessary.

Many seeds will germinate quicker with bottom heat, hence the heat mat. I have a bigger heat mat that has space for 4-trays, a 1-tray mat, and I also use the heat of the shop lights as a source of bottom heat to increase my available germination area. For this first part of germination, a good source of light is not necessary. However, once the seeds have germinated and start to leaf out, they will need to have access to good light in order to grow nice strong, sturdy stems. Leggy (tall, skinny, weak stemmed) plants tell you that you need to increase the light available or perhaps get them closer to the light. The fluorescent shop lights are great; they don’t put off a lot of heat, so you can get the plants quite close. This time of year, trays are constantly moving off the heat mat to the light and then potted up and eventually outside somewhere to continue hardening off before getting transplanted out.  

My main germination space made up of 2 market tables stacked on top of each other with fluorescent lights hanging from the legs.

I have a fairly cheap, simple setup for germinating and growing out seedlings. I stack one 6” market table on top of another, and then I am able to hang a 4'-6 bulb light fixture with light chain from the legs of each table to provide light for 4 trays of seedlings on each of the 2 levels, giving me space for 8 trays of seedlings under light. On the top of the upper table, I have my 4-tray heat mat where I germinate seeds under clear lids, and once they have good germination, they get moved under the lighted area (with lids on at first). The lights are on a timer to provide about 16 hours of light a day. I also have a third light (just 2 bulbs) that has more clearance where I can move plants as they get bigger to begin hardening them off. From here, they will either go into the Greenhouse (if it’s early and too cold and windy outside or if they are heat lovers that are more needy) or on benches outside as they await being transplanted into the garden.

Third light with more clearance for seedlings as they get taller.

For direct-seeded crops, the environment is different, but the principles are generally the same. Once planted, the seeds should be kept constantly moist through germination, not sopping wet as they may rot but do not allow them to dry out, or you might interrupt germination or cause the germinating seed to die. Floating row cover is a good way to help keep seeds moist through germination; you just need to remember to peek underneath on a regular basis to monitor moisture, keep an eye on weed seed germination and also to make sure pests don’t mow their way through newly germinated seeds. Slugs around here can take out an amazing amount of young seedlings and really appreciate the warm, moist environment provided for germination. Observation is key.