Germinating Tomato Seeds

Germinating tomato seeds, or more specifically growing tomatoes from seeds, really isn’t that difficult. Using seeds, you can grow a whole lot more varieties than what you find in your local garden shop.

If you’re adventurous, why not try growing a new variety (or varieties) of tomatoes from seeds? Maybe some heirloom tomatoes, while you’re at it?

Tomato Seed Germination Rates

Before I get into the technical aspects of planting, I want to discuss germination rates for tomato seeds. It’s quite rare for all the seeds you plant to germinate, or once germinated, to thrive. While I’m glad when it happens, I don’t expect it. In my experience, 75% to 80% of my seeds in any given packet germinate and thrive. So, I normally plant 25% more than I think I will need of a particular variety. If everything germinates and thrives, I can give away or sell the extras.

A lot of things affect the tomato seed germination rate. For one, how old are the seeds? Whether you buy them online (which is what I do mostly) or pick up the seeds in a garden center, you don’t know how long those tomato seeds have been sitting around. The older the seeds, the lower the germination rate.

(That being said, I have seeds 10 or more years old that still germinate…just slower and with a lower percentage.)

Another issue is how have the seeds been stored? Two things can hurt seeds; too much humidity and…not enough humidity! Too much, and the seeds want to sprout, or else they can mold. Too little and they can dry out and not germinate at all.
How Long Does It Take for Germination?

There isn’t really a set time for tomatoes, as different varieties germinate at different times. The fastest I’ve ever had is 3 days; the slowest 12 days. In general, most germinate in 5 to 7 days. I generally wait 2 weeks before I consider a set of tomato seeds a lost cause for germinating.

Right now, I have SuperSweet 100, Brandywine and White Bush sprouting. SuperSweet 100 raised it’s head after 4 days and at 7 days (which is today), I did the first transplant to a slightly larger container. I had a 75% germination rate with a fairly new packet of seeds. (I planted 4 seeds and 3 germinated.)

White Bush is the next in line, sprouting yesterday (6 days). Brandywine is just starting to poke its head above ground today (7 days). My germination rate is really low with these two, because I am using 10-year-old seeds. (I just did plant some newer Brandywine seeds today for comparison.)

I have about 3 other varieties that haven’t sprouted yet, but once again, these are all 10-year-old seeds. What can I say, I am curious as to how they grow and thrive! Some of my 10-year-old seeds are pretty rare, and I want to try them again.

(Read my update on how well the 10-year old seeds germinated, 10 days out – I was amazed!)

Germinating Tomato Seeds – Tips

First, make sure that you have a nice, warm place for your seeds to germinate. I use a windowsill greenhouse in a south-facing window; some people use the top of their refrigerator. Others use a seed heat mat or a grow light. A soil temperature of around 80 degrees is ideal for tomato seed germination.

The “soil” I’ve had most luck with is a seed starting mix. It’s lighter than a regular potting mix, so it’s easier for the plants to poke their heads above ground. The soil needs to be moist but not wet.

I tend to plant my seeds rather shallow, 1/4 inch or less. Keep the humidity high while you’re waiting for the seeds to germinate. This is where I like the mini greenhouses (windowsill and table-top, because they have a cover that keeps the seeds and soil nice and moist. Not to mention they take up very little space.

I have used jiffy pots and compressed peat disks, with fairly good results. The main reason I don’t generally use them these days is because I plant 5 to 10 different varieties at a time, and I need to label my pots with the variety name. But if you just plan on growing one to three varieties, then the jiffy pots and compressed peat disks work fine.

Once your seeds have sprouted, they need light — from sunlight or a grow light. If you live in a chilly climate, grow lights might be your best bet. Where I live (South Florida), a windowsill works fine just about any time of year.

I hope all these tips have helped, and that you have much success in germinating tomato seeds!