Senior Gardening

One of the Joys of Maturity
The Senior Garden Blog Archive
Features & How-To's
Affiliated Advertisers


Growing Your Own Transplants - Page 3
September 9, 2015

Some Seed Needs Light to Germinate

While most vegetable seed doesn't need light to germinate (and may require total darkness), some herb and flower varieties absolutely require light for germination or may germinate better with a bit of light. Seed catalogs or seed packets usually tell whether a type of seed requires light for germination. Online, a North Carolina State Extension Service document has a nice chart of light requirements for some vegetables and flowers, while Fedco Seeds provides an amazingly complete listing of growing information for herbs.

Thyme seed covered with clear plastic wrapPlant rack - January 2, 2014When planting seed requiring some light, one faces the challenge of keeping the seed on the soil surface moist while still providing the necessary light. One way to meet these requirements is to cover individual pots or entire flats with clear material that allows light to reach the seed. For individual pots, a small piece of clear plastic wrap held on with a rubber band will suffice. A seed flat or tray can be covered with a clear humidome. The clear materials transmit light, but also hold in moisture, essential for seeds sitting on top or slightly pushed into the soil.

One can also sprinkle a very light layer of vermiculite around seed requiring light to germinate. The rough texture of the vermiculite allows gaps where light can penetrate while also holding in soil moisture.

For seed requiring bottom heat (with or without light) to germinate, we use humidome covered flats over a Gro-Mat soil heating mat under our plant lights. I added a Hydrofarm Digital Thermostat to the setup to more accurately control soil temperature. It has a temperature probe that can go right into the potting mix.

Examples of plant seeds we grow that need light to germinate include thyme, sage, petunia, impatiens, gloxinia, snapdragons, and to a certain extent, geraniums. I won't deal with Growing Geraniums from Seed here, as I've done a whole series of articles on that subject already. The older pieces make for some interesting reading, however, as I made a lot of mistakes along the way.

Interestingly, vinca (periwinkle), a flower we love to use along the edges of our raised beds, requires absolute darkness to germinate.


Need Light

Catnipicon- perennial - 60-70° F

Dill - annual - 60-70o F

Oregano - perennial (zones 3-9) - 70o F

Rosemaryicon - perennial (zones 7-9) - 65° F (one source suggests 55° F night, 70° F day)

Sageicon - perennial or hardy annual - 70o F

Thyme - perennial - 70o F


Basil - annual - 65-70° F

Paprika Peppers - annual 80-90° F

Parsley - annual - 70-80o F

Note that herbs can take a good bit longer to germinate than most vegetables. While most herbs come up in 7-14 days, parsley is one that can come up in days or take weeks to germinate. Again, Fedco's herb chart is a good resource on germination times. If you're not an organic grower, adding a bit of Captan to the soil surface can help hold back mold from forming on the soil surface during extended germination periods.

Shallow well pump and herb garden
Herb garden on August 1, 2016

After years of procrastination, I finally installed a shallow well pump in 2016 that my darling wife had given me. The pump head in its box served as a door stop for many years before being stored many more years in a vacant upstairs bedroom.

Having gotten the pump in place and working, I moved on to a job I'd long wanted to do, putting a small raised bed for herbs around our shallow well. I used cedar 4x4s for the raised bed, as I couldn't afford 6x6 cedar lumber and simply wouldn't use any kind of treated lumber near a water source.

In its first year, the raised herb bed produced glorious crops of basil, parsley, sage, rosemary, dill, and thyme, along with a lot of lovely flowers. I only wish I could and would have put in an herb garden years ago. Running from the kitchen when cooking to trim a bit of fresh thyme or parsley was a real treat.

The table at right is a cheat sheet I made to help me remember how to start various herbs. Our herb garden is pretty limited, as I only grow those herbs we frequently use. I've successfully started many herbs for years, only to have them languish under the cold frame or on our back porch for lack of an area where to put them.

Note that one doesn't have to have an herb garden to grow this stuff. We've grown, harvested, dried and saved basil, parsley, oregano, and sage for years that was grown along the borders of our vegetable garden plots. But having a space for some perennial herbs is really nice, if they can survive our winters here in west central Indiana.

Please take my comments on growing herbs with a grain of salt. I've grown some herbs for years, but am a total rookie at growing dill, thyme, rosemary, and other herbs.

Something Special

About five years ago, I started messing around with starting our petunias in egg cartons. My mother used to start plants in egg cartons on the windowsill when I was growing up. While we actually germinate ours in egg cartons, we do the germination under plant lights with the egg cartons in a tray covered with a clear humidome. We also use bottom heat to get them up. But once germinated, the petunias go on a sunny kitchen windowsill, adding some welcome color to our home during the dead of winter.

Petunias in egg carton on windowsill

See Starting Petunias in Egg Cartons for complete directions. Note that the petunias rather quickly outgrow their egg carton homes.

Starting Asparagus Seed

Most folks start an asparagus patch with roots purchased online or at a garden center...for good reason. Asparagus takes some tricks to germinate and then takes a long time to mature. One can pick asparagus transplanted from roots in a year or so, but from seed, it normally takes three to four years to get a stand strong enough for a heavy picking.

Having said that, I've started two asparagus patches from seed over the years. The first I began in our farming years, using seed because I was too poor to afford roots and too dumb to realize I'd really have saved a good bit in the long run by just buying good rootstock. The second patch from seed was just orneriness on my part. I'd done it once, so I knew I could do it again.

Asparagus seed is what is known as a "hard seed." It requires stratification and/or scarification to germinate well. Stratification has to do with soaking and freezing (and thawing) seed, while scarification is a process of sanding, filing, or in some other way thinning or cracking the hard seed coat so moisture and oxygen can reach the seed interior and trigger germination.

I ended up the last time I started asparagus stratifying some of the seed and scarifying the rest, getting a giant flat of asparagus plants, but only in the late fall...far too late to transplant. So I overwintered the plants under our plant lights and set them out the next spring.

Our How-to feature story, Growing Asparagus, gives a lot more details on starting and growing asparagus.

Beyond asparagus, I don't know of another vegetable seed that requires such extreme treatment. Many tree and shrub seeds do require such treatment to germinate. We ran into some hard geranium seed a few years ago that we had to scarify and wait seemingly forever for it to germinate.


When I transplanted a couple of yellow squash plants into our East Garden in the spring of 2013, I also started another pot of yellow squash under our plant lights. When one of the transplanted squash plants failed early on, a replacement was ready to go into the garden to pick up the slack and keep us covered up in the delicious summer treat. I also started yet another pot of squash when the replacement plant went in, and repeated that practice several more times over the summer.

We also start lettuce, broccoli, and cauliflower transplants during the summer for our fall garden. So starting your own transplants can be an all season long activity.

Getting Fancy (and expensive)

Many seed packets and/or catalog descriptions will specify an ideal temperature range for germinating a flower or vegetable. Sometimes that's pretty much a recommendation, but not absolutely essential, and with some varieties, a little bottom heat makes the difference between getting only a few seeds to germinate and nearly every seed germinating.

Since I've endeavoured to keep this piece ad-free other than a few embedded links, I'll just give you a link here to some seed starting supplies from our Shopping Guide for Gardeners page that has links to heat mats, thermostats, trays, labels, and such.

Saving Seed from Year to Year

One of the economies of growing ones own transplants and for gardeners in general is saving unused seed for future use. Not all seed stores well, with onion seed immediately coming to mind as a seed to buy fresh each year. But most other garden seed can be saved a year or more if stored in a cool, dry location. A dark canning jar with a tight fitting lid placed in a relatively dark and cool spot is ideal for storing saved seed packets.

We go a bit further with saving old seed, keeping most of our stored garden seed in a manual defrosting chest style freezer in our garage. We have successfully germinated twenty year old cucumber, tomato, and gloxinia seed kept in constant frozen storage over the years. Most seed probably won't store that long, but one can often beat published seed saving tables by many years using frozen storage.

Odds 'n' Ends

Hopefully, I've given you the bare basics on growing your own garden transplants. Do note that the information above may be subject to error. I'm not a trained horticulturist or a master gardener. What I've written is what works for us, on our ground, under our growing conditions...on our better days. There are links below for further information on the subject.

This feature article has taken years to get off my hard drive and onto the internet. I peeked at the "Get Info" for the original file and found that I'd started this feature story early in 2011. Like many story starts, I worked on it a bit, and then set it aside when I hit a point where I didn't know where to go next with it, or just plain got frustrated with the idea. In 2014, I transferred the original content to a newer HTML format, worked on it a bit more, and then forgot all about the story again.

What gets me is how do you effectively pass along what has taken over fifty years to learn (and the learning process, believe me, continues to this day)? The answer, of course, was to start small. Pick one or two things folks could easily and successfully start for their gardens. Beyond that, there are lots of excellent articles online about how to start and care for specific vegetables and flowers. Our Gloxinias feature story is an example of such a plant specific article. Our How-To and Features sections also give some full season instructions for growing various garden crops.

Other Good Sources of Information on Seed Starting



That's all! Now, go grow something!

pages   1 2 3      


From Steve Wood, the at Senior Gardening

Enjoy the content on Senior Gardening?

If so, why not come back to our Senior Gardening Advertisers page the next time you plan to purchase something online and click through one of our ads. We'll get a small commission from the sale, and you won't pay any more than you would have by directly going to the vendor's site.

Ads shown on this site do not represent an endorsement or warranty of any kind of products or companies shown.
The Senior Garden Blog Archive
Features & How-To's
Affiliated Advertisers

last updated 1/1/2018