Starting Plants From Seeds

Seedlings at Wiese Acres

With heavy clay soil that is so slow to warm in spring, and in an area with a relatively short growing season (about 120 days), there are some plants that need a little head start.   I’m ok with that, because it gives me an excuse to putter in the dirt a little earlier.

Most vegetable seedlings are large enough to transplant into the outside soil with about six to eight weeks growth, so mid-March is when I begin planting in earnest.  Sometimes I start earlier, if I want to grow some of the flowers or the few vegetables that need a bit longer.  I usually don’t start a lot of my own flowers.  I find that if I add up the costs of  the materials, the electricity for lighting and air flow, and my time, it is just as cheap or cheaper to buy plants from a garden center. 

I start my own vegetables, though, because I have a much larger variety selection from which to choose. I like the North Dakota State University tomato introductions Cannonball and Sheyenne for their hardiness, taste, and productivity in our climate.  I can’t find those in garden centers, so I grow my own.  Likewise for bell peppers, such as King of the North, which is a great producer here but rarely ever is sold as a transplant.  Megaton cabbage, Belstar broccoli, and Graffiti cauliflower are a few more examples of seeds I can buy but rarely find transplants.  So, I grow my own.   Well, that and the fact that there is just an immense satisfaction in watching those seedlings push through the top of the soil and advance from seed leaves to the first couple sets of true leaves, to a nice healthy transplant ready to go in the garden.

The first key to success in seed starting is to use good  seed.    There are a lot of different places to find seed.  You can buy locally from garden centers, big box stores, or you can order from catalogs.  You can save your own or trade with a gardening friend.  When purchasing seeds, prices range from a few cents to a few dollars.  Number of seeds per packet also can vary greatly from one brand to another.  The quality of the seeds, however, if purchased from a vendor, is no different.  The minimum acceptable percentage of germination and seed purity is governed by law. 

The newer hybrids and unusual varieties are generally more expensive than the more common varieties you find in a big box store.  Organic and heirloom seeds also tend to be more expensive.  

And here I need to take a little bit of a detour from seed starting.  It’s important to know what you are paying for and why you want to pay for it.  Heirlooms are great and certainly some people swear that an heirloom variety tastes better than the newer hybrids.  They are also more disease prone and in general, just a lot more finicky than the hybrids.  The goal of hybridizing is to take the best features of each parent plant and leave the not so desirable features behind in the creation of a new variety.  If you are willing to put up with the not so desirable features in exchange for something you do find desirable about the heirlooms, by all means, plant heirloom seeds.

If you are prepared to organically raise your seeds from start to harvest and storage, then by all means use organic seeds.  But, if you are going to spray the grasshoppers with malathion or give the plants that little shot of Miracle-Gro when things are looking a bit puny, then you are not going to harvest an organic product.  So, just go ahead and buy the less expensive seeds.

In general, smaller packets of seeds are more expensive on a per plant basis.  That said, it is wise to not purchase more seeds than you are able to use up in two to three years.  Each seed has a living plant embryo that must stay alive in order for the seed to germinate.  The longer seeds are in storage, the more plant embryos die and you end up with seeds that won’t grow.

If you do have excess seeds, you can store them for the next year.  Store the seeds in an air tight container in a cool dark place.  I use empty, washed and dried medication bottles with tight fitting caps for my storage containers.  I ty to save the small silica packets that come in various items and stick one of those in the bottle to absorb any humidity that might get inside and cause molding or sprouting of the seeds.  If I don’t have enough silica packets, I take a small piece of tissue, put about a teaspoon of dry powdered milk in the center, tie it shut and drop it in the container with the seeds.  It will work nearly as well as the silica packets.

My mom started a commercial greenhouse when she and Dad retired from the farm.  She’d always started all her own plants and enough for all of her kids’ gardens, but with retirement, she thought she had time to do more.  So, Wilma’s Greenhouse was born.  Mom always started her seedlings in flat beds made out of old milk cartons.  She would soak the milk cartons in a solution of 10% bleach for about a half hour, rinse them well, and let them dry.  When they were dry, she would tape the pour spout closed with masking tape, cut the top off the long side and fill them with her homemade potting mix.  Then, she’d place the seeds in the carton and wait for them to grow.  Once they had their second set of true leaves, she carefully teased each one out of its milk carton home and transplanted it to a peat or plastic pot, or a six-pack.   Mom never used a four pack – she just couldn’t imagine why anyone would waste their time with just four plants.  For plants that were sold as individual items, she saved pudding cups, washed them well, poked holes in the bottom for drainage and planted away.  I believe Mom was the first Queen of the Reduce, Reuse, Recycle movement.  People never cared that she didn’t use the fancy nursery systems.  As many of them said “we come to Wilma’s Greenhouse because we know they are the best plants in the state”.    She ran that successful greenhouse until she was nearly 80 years old.  She never had an employee.  It was just her and Dad most of the time, and if she was really in a bind, she would recruit whichever of us kids or grandkids had time to come help for a little bit.

She also mixed 100% of her own potting soil and sterilized it in the ovens before planting.  This always led to a real “earthy” aroma permeating the house as she heated and stirred that soil until there were no pathogens or weed seeds left alive.  We all tried to avoid visiting during “dirt cooking time” – Peeuuw.  Her frugality and willingness to “make do” and re-use allowed her to sell her very healthy greenhouse stock for less, which led to a very loyal customer base who to this day, when I come back to my home area, will tell me “we sure miss your mom’s greenhouse”. 

I've taken some shortcuts with my seed-starting, since I work full time and do my greenhousing as a hobby.  I also do not have the patience to be as gentle as I need to be when teasing those tender roots apart or moving them for transplanting.  For most plants, I use plastic containers that fit into a solid tray lined with a water absorbent mesh.  For plants that resent transplanting, like watermelon and cantaloupe, I use peat pots that I can just set into the planting hole without touching the plant roots.   I plant my seeds directly into good quality potting soil in a large enough pot that they can live in one home until they are moved to their permanent garden location. 

I know most sources recommend using the soilless seed-starting mixes because they are lightweight, with a “fluffy” texture and porous nature that is well suited to seed germination.  I have started seeds in seed-starting mixes and really have not seen any difference in germination and growth from this type of mix to a high quality potting mix.  Or my mother’s homemade potting mix, for that matter, which, now that I think about it, was probably a lot higher quality than anything I can buy today.  Using the seed-starting mix means that you will absolutely have to transplant seedlings into potting soil and may have more of a challenge keeping them adequately watered and nourished in the meantime.

 A word of caution, though, with directly sowing into regular potting mix.  Make sure that the soil is never allowed to dry out.  It will pull away from the sides of the container and may damage those fragile roots, or it can develop a hard crust on the top,  which will not allow the seedling to break through.

I re-use my plastic containers and trays from year to year.  I sterilize them before re-using them with the 10% bleach solution that Mom used to sterilize her old milk cartons.    I start the planting process by emptying the bag of potting mix into a large, flat container.  I use a “calf-sled”,  a plastic bin that is about three feet wide by five feet long by 18 inches deep.  It’s called a calf-sled because that is its original purpose.  When a newborn calf needed to be moved, the calf was loaded into the calf-sled, Momma Cow was allowed to sniff the whole contraption, and then the sled was attached to a small tractor, a four wheeler, or a couple of strong arms, and transported to a location of safety with Momma Cow following docilely behind.  Or, at least, that’s how it’s supposed to work.

 Anyway, the calf-sled as a soil mixing tub is a lot more consistent about acting the way I want than those momma cows ever were.  I like the shallow depth because it is so much easier to get the entire mass of soil mixed.  I pour the potting mix into the tub, remove any large pieces of bark and break up any large clumps. I sprinkle water on the surface, mix it in with my hands, sprinkle a little more, mix a little more, and keep repeating until the potting soil is all nicely moistened but not wet or soggy.  Then, I gently pack each plastic container about two-thirds full of potting soil, place the container in the tray, and set the tray aside to plant.

If I am using fresh seeds, packed for the year of planting, I will only plant one or two seeds per container.  If I am using older seeds that may not germinate as well, I may put three seeds in each container.  To keep my hands from getting wet and having the seeds stick to them, I use a pointy tipped tweezer to grasp the seed and set it gently on top of the soil in the container.  When all the containers in a flat are planted, I mark each container with the name of the plant and the date planted.  I use old mini-blind blades cut to just a couple inches taller than the container and write on them with a permanent marker.  Then, I go back to my calf-sled full of potting soil and sprinkle additional soil on top of the seedlings to whatever depth is recommended for that particular seed.  If it is a seed that requires light to germinate, I cover it with a thin layer of vermiculite rather than soil.  The vermiculite holds the seeds and the soil in place while letting the seeds absorb the light they need to germinate.   If a seed requires complete darkness to germinate, I cover with soil and place the whole container in a dark bag. 

After the seeds are covered, I use a sprinkling water can to give them a gentle watering to settle the layers of soil together.  Then, it’s a matter of finding just the right spot to keep them nice and cozy for awhile.  Before the days of the greenhouse, I remember Mom having seed flats setting in front of every heat register where the warmth from the old coal furnace poured into the house.  As the seeds germinated, she’d move them to areas of more light as needed. 

One thing I don’t remember her ever doing is putting her newly planted flats on the windowsills.  She always said why would you put something that needs nice, cozy warmth in the coldest spot in your house?  Makes sense, I guess.  And I am certainly not going to argue with the woman who was widely believed to know more about gardening than any professionally trained gardener.

Mom covered the milk cartons with a thin layer of plastic to keep warmth and humidity bathing the seeds.  Once again, the Queen of Reduce, Reuse, Recycle, figured out an environmentally friendly and economical way to make this happen.  She saved bread wrappers, slit them open to lie flat, and placed them over the top of the milk cartons, securing them with large rubber bands.   Nowadays, you can buy plastic domes that accomplish the same thing, but at a significantly higher cost.

Hot Frame - Wiese Acres

I am pretty lucky.  My husband is very handy, and while he doesn’t share my love for all things gardening, he does tolerate it.  A few winters ago, he asked me what I wanted for my birthday.  I produced a drawing and said “this”.  He went to work and built me a lovely “hot frame” for seed starting.  The frame is sized so that my planting flats set side by side.  It is heated with seedling heat mats on the floors of the shelves.  The top shelf is all enclosed to keep warmth and humidity levels stable.  The lower shelf is open for larger containers for starting dahlias, cannas, and other large plants. 

Seedlings on warming mats - Wiese Acres

I set the flats in the hot frame, turn on the warming pads, close it up, and check daily to make sure the potting soil isn't drying out and to see what might be sprouting.  It is critical to not allow the potting soil to dry out.  Doing so likely will kill any tiny emerging seedlings.

As soon as the seed leaves have emerged, I move the plants to the greenhouse shelving unit that sets far away from the garage doors.  Most springs, it is still cold enough that the blast of frigid air that comes in when the big garage doors open would not be good for the seedlings.  The shelves are on the far end of the garage and are protected by enclosed cupboards between them and the doors.    The air temperature in the garage is maintained at about 62 degrees.  

Light and air flow are as critical to successful seed starting as adequate (but not too much) moisture and warmth.  Windowsills seem like a logical place to provide enough light for seedlings, but there are a couple downsides to that.  As I mentioned earlier, the windowsill is the coldest place in the house, especially at night.  During the day, however, it can become scalding hot and dry out the soil quickly and even sunburn the plants.  Also, seedlings need 12 to 16 hours of bright light each day.  In spring, most areas don’t have that many hours of natural sunlight yet.  Finally, the sun coming in through a window hits the seedling from the side, rather than the top.  That encourages the seedlings to grow sideways, with crooked, weaker stems.  Light directly from above will encourage straight, sturdy stem growth.

Greenhouse shelves with lights - Wiese Acres

My greenhouse lights are nothing elaborate.  They are inexpensive shop light fixtures that hold two fluorescent bulbs each.  I use one warm blue-white or natural daylight and one cool white light tube in each fixture.  This gives the seedlings essentially the same light spectrum, at a much lower cost, of the specifically labeled “grow light” bulbs. 

The light fixtures hang on adjustable chains so as the seedlings grow, I can move the lights up, always keeping them about two inches from the top of the seedling.  The lights are on a timer set to turn on at 6:00 AM and off at 10:00 PM, giving the plants a full 16 hours of light each day.  It’s important to give most plants a period of darkness each day in order for them to develop properly.  Having the lights on a timer means that I don’t have to worry about remembering to turn the lights on or off.

Floor Fan - Wiese Acres

A floor fan to provides constant air movement around my seedlings.  This helps strengthen the stems and also keep humidity borne diseases like damping off at bay.  It runs on a low setting around the clock – except when I am out there working on my seedlings or other projects.  There is something about the sound of that whirring fan that is just not soothing to me…

When the seedlings are very tiny, I water them only from the bottom to protect the fragile new stems from the force of water hitting them directly.  As the seedlings grow, I water them with a sprinkling can that allows only a fine sprinkling of water.  This helps prepare the seedlings for the rains and harsher watering they will experience when they hit the mighty outdoors.  It is important to not leave standing water in the seedling trays.  Fungal disease (damping off) can quickly wipe out the entire crop.  The moisture mats in the bottom of my seed trays hold just enough water to keep humidity levels adequate and to keep moisture levels consistent in the soil.  If there is standing water on the mats when I finish sprinkling, I drain them. 

In addition to not overwatering and keeping air movement constant, I have found one other thing that seems to help prevent damping off disease in my seedlings.  I admit, I was skeptical when I first read about it, but I thought, hey, it’s cheap and it can’t hurt.  Watering with a solution of chamomile tea is thought to decrease the chance of fungal diseases.  I fill my one gallon watering can, dump about 3 tablespoons of chamomile in it, and let it steep overnight.  In the morning, I mix in fertilizer and water away.  Since I started this, I've had almost no loss to damping off.  I can’t say for sure it’s the chamomile, the watering technique, the circulating air, a combination of all of these, or just plain luck, but like I said the chamomile is cheap.

While the seeds are germinating, they do not need any fertilization.  The seed itself contains all the nutrients it needs to start that little sprout growing.  Once the true leaves begin to emerge, it is important to provide regular nutrition for seedlings.  I use quarter strength fertilizer in two to three waterings a week.  My preference is fish fertilizer because the likelihood of it burning the seedlings even if my “eyeball” measure is a bit off and my quarter strength ends up inching closer to third or half strength sometimes, is pretty low.  The seedlings seem to absolutely love this treatment.

Once the seedlings have developed at least one set of true leaves (the ones that actually look like the plant rather than the seed leaves that are almost always smooth blade like leaves), I cull the less desirable seedlings from any pot where more than one has germinated.  I use a cuticle scissors to snip off all but the strongest seedling right at soil level.  This effectively kills that seedling without disrupting the roots of the remaining desirable seedling.  

Sometimes I have more than one healthy seedling and just can't bear to destroy one of them.  I remove the root ball and carefully tease the roots of the two plants apart, being very careful with the tender roots and stems to avoid any injury.  This generally only works if there is plenty of space between the desirable seedlings.  If they are right next to each other, it will be nearly impossible to separate them without damaging and risking the death of both seedlings.  If I can get them apart, I immediately re-plant both into appropriate containers.

If the seedlings outgrow their original home, they get transplanted into a larger container.  I use peat pots, plastic drinking cups, Styrofoam cups – whatever I have on hand that is the right size.  I make sure there is good drainage and then place soil to cover the bottom of the container.  The seedling needs to be lifted out of its original container by the root ball. I use an old kitchen spoon with a very thin edge so I can slide it down the side of the container and edge it under the root ball at the bottom.  A little lift of the spoon usually brings the entire root ball right out.  Alternatively, you can place two fingers on either side of the seedling stem and tip the entire pot upside down into the palm of your hand.   It’s important to not put too much pressure on the stem or at the growing tip.  Pressure on the stem can crush it, and keep the seedling  from being able to get nutrition to the upper part of the plant, leading to its death.  Damage to the growing tip (the very top of the plant) will result in seedling death, as no new growth can be initiated without that tip intact.  Once the seedling is loose, I set it in the new container  with root ball completely intact and gently tap soil in around the plant.  With most seedlings, it is ok to cover a bit more of the stem than was originally in the soil, again being very careful to not crush the stem or growing tip.

Once the temperatures are not likely to drop down below about 25 degrees at night, I move the plants to my little portable greenhouse.  It’s a simple steel frame covered with plastic.  I can heat it some with an electric heater, but can’t keep it from freezing in extreme cold, so my plants stay in the garage until about mid-April, generally.  After that, they go out where they begin to get exposed to a little harsher conditions to prepare them for their eventual move to the gardens.  

Small, portable greenhouse - Wiese Acres

Seedlings need to be “hardened off” before being transplanted into the garden.  They've been protected from harsh winds, hot sun and high and low temperatures.  They won’t have that protection in the garden, so they have to be taken through a process to toughen them up.  This should start at least two weeks before transplanting to the garden.  It’s easier to do that in the greenhouse, where I can open and close the curtains that serve as windows.  I start by only opening the curtains an inch or two for an hour or so each morning.  I gradually increase the size of the window opening  and the length of exposure until the windows are open all day long most days. 

 Without a greenhouse, seedlings can be set outside in a protected area for increasing lengths of time, gradually moving them more and more into the open over the course of two weeks.  At the end of two weeks, they should be fine in the open until transplanted into the garden, unless freezing temperatures are forecast.  Even the most hardened off seedling will not survive temperatures below 32 degrees.

Once I'm through this process, it’s just a matter of waiting until the time is right to transplant into the garden.  That’s when I know the gardening season is officially upon us!