Growing a Garden: Starting from Seed

Growing plants from seed requires more steps than growing from a seedling. On top of that, every plant is different, and as such slight variations may apply. There is no one-size-fits-all solution to growing from seed, but there are ways to make sure you're doing everything you can. Below we look at some things to consider when starting a garden from seed. 

Seed Choice and Timing

Taking time to research what vegetables you want to grow is essential to a successful garden. It provides you information like planting time, harvest time, and, sometimes, even feeding schedules.

It's best to understand the length of your growing season before purchasing seeds. First, be sure to check the information on the plants you aim to germinate. There are often planting windows where the producer provides a set number of weeks to seed before the last frost. You may also find information about how long the plant takes to produce table ready food. Take this information and ensure your season is long enough to grow and develop a worthwhile crop of the fruits and vegetables you chose. Some plants will simply not produce in certain climates, and it's best to know which ones work for you before you buy your seeds. 

Every plant is different, and, as such, growing time varies. You will find that a typical growing period from seed to ready-to-plant seedling is three to six weeks. This period is necessary to grow a hearty plant ready for outdoors.

Also, see if the plants you plan on growing from seed prefer outdoor germination or "direct sow." Some simply have trouble starting inside and have better chances in the ground. For these, you will need to follow the plant-specific instructions for seeding and germination. Typically, you can seed cold-hardy plants in late winter or early spring, while heat-loving plants are in mid-to-late spring. Some plants even prefer fall planting for a spring crop. Again, check the length of your growing season to guarantee enough time for a proper harvest.

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Seed Saving at Home

Perhaps you have been collecting seeds from grocery store vegetables or maybe last year's garden. Amazing! Seed saving is an ancient practice and a great way to develop local heirloom varieties. When planting seeds not produced by an official distributor, there are a few things to consider. First, seeds from grocery store vegetables and fruits may not provide what you're expecting. Remember, grocery food ships from around the world, so some of the varieties may not succeed in your climate. You may even find that some hybridized seeds won't produce a seedling. 

Can I Plant Old Seeds?

What about those seeds tucked away in the desk drawer you forgot? Old seeds run the risk of failing to germinate. There are ways to store your seeds for more extended periods, but if this is your first season, your best bet may be to start with seeds purchased from a reputable source.

How To Choose What To Plant At Home

So, let's assume you want to grow a tomato plant this summer. You know that this heat-loving vegetable doesn't handle frost well and you plan on starting the seeds indoors. The problem is you live in a colder climate, but you know what to do. You go with a quick maturing tomato, like the Scotia variety, which develop in 60-days and place an order for your seeds. But what's next?

Container and Soil

You can start your seeds in purchased planting trays or containers you find around the house. These containers can be old margarine tubs, yogurt cups, or plastic storage containers and are great things to reuse as a means to reduce your waste output. Whatever you plant in has enough room for at least 2-3" of root growth. Also, check and make sure there are drainage holes at the bottom, even if you have to poke them yourself!

If you're reusing an old container, be sure first to clean it with soapy water. This initial cleaning helps wash away potentially harmful microorganisms that could hurt the susceptible seedlings. 

You also need to consider what plants you will be producing in these pots. Lettuce, cucumbers, melons, and sunflowers have sensitive roots and require special care in transplanting. Speaking from experience, growing in trays for these types of plants is not impossible. As the plants mature, you may need to observe them to ensure they don't become rootbound.

What Is the Best Soil Mix to Start Seedlings? 

To begin, you're going to want fresh soil to start your seeds. A sterile soil mix ensures that there are no soil-borne diseases to attack your tender seedlings. For this, you have a few options. One is to buy your soil in bags from your local garden supply.

How To Sterilize Soil For Seeds and Plants

For the do-it-yourselfers who want to try to do it at home, there are various soil sterilization techniques you can try. The sterilization methods below will ensure your soil is free from pests, diseases, and weed seeds.

How To Sterilize Soil With a Pressure Cooker

Steaming your soil is one of the best and most popular ways to sterilize potting soil and can be done with a pressure cooker. Pour 2 cups of water into the bottom of the pressure cooker. Then place a shallow pan into the pressure cooker with no more than 4 inches of soil. Cover the pan with tin foil and close the lid with the steam valve open. This allows the steam to escape. Depending on your model, cook at 10 pounds of pressure or on the custom cooking setting for 15 to 30 minutes.

How To Sterilize Soil With an Oven

To sterilize soil in an oven, place the soil onto a baking sheet or pan no more than 4 inches deep and cover with tinfoil. Then bake for 30 minutes at 200 °F (93 °C). After 30 minutes, remove the pan from the oven and let sit until cool with the aluminum foil on. Do not bake at temperatures higher than 200 °F as it could produce toxins.

How To Sterilize Soil With a Microwave

Sterilizing soil in the microwave is an easy and quick process, but may take longer depending on the amount of soil you need to sterilize. Using a microwave-safe container with vents, place moist soil in the container and place it in the microwave for 90 seconds. Remove the soil from the microwave and let cool. You can repeat this process for the remaining soil you wish to sterilize.

How to Make Soilless Growing Mix At Home

If you're looking to use a soilless growing mix, you can purchase from your local garden supply or make it yourself. To do so, combine two gallons of peat moss with two gallons of perlite or vermiculite and mix thoroughly. After the plant's "true" leaves begin to emerge, you can start feeding them a diluted amount of liquid-soluble fertilizer every week or so. Some fertilizer options to consider are compost teas, worm teas from your vermicompost, or store-bought liquid-fertilizer. 

Please note that the peat moss mentioned above is a non-renewable resource. As an alternative, consider using coir, the outer husk of the coconut. It has become a popular renewable alternative.

Once you have your growing medium ready, be sure that it is moist and not heavily saturated when getting ready to start your seeds.

Prepare For Your Crop

As you are waiting for your seeds' arrival, you're on the hunt for some containers to grow your Scotia tomatoes. You find several old food-grade plastic containers and poke holes in the bottom for drainage. You choose to fill them with a soilless medium and make sure there is enough room in the vessel for root growth. 

Sowing Your Seeds

Now that you have prepared your containers with your growing medium, it's the perfect time to sow the seeds. The packet that you received your plants will often have recommendations for how deep to sow. A standard measurement in planting is a depth of two to four times the diameter of the seed. But as with everything, this is not always true. Some seeds prefer to grow on top of the medium and not buried. Confirm individual seed planting depths before sowing. 

Ideally, when starting from seed, there can be between one and three seeds per cell (if starting in a tray) or small container. Multiple seeds act as a redundancy if one fails. This planting method is standard and often determined by germination rate or the percentage of successfully germinated seeds under proper growing conditions. If multiple seeds sprout in a cell, as the plants mature, you can clip the weaker of the seedlings and leave the heartiest. After sowing in the seeds, add a thin layer of vermiculite atop the medium. This layer acts as a secure barrier for the tender seedlings to push through.

Estimate How Many Seeds to Plant

Examining your seeds, you note that you received 350 in your tomato packet with a germination rate of 90 percent. This number means that of your seeds, 35 are anticipated not to produce. But that is still a lot of seeds, even if you wanted to grow a dozen plants. Using the end of a pencil, you poke a hole approximately four times the diameter of the seed and sow two. Sprinkling vermiculite over the top of the seeds, you are content with your work. In the end, you decide to start twenty because it's your first time and you want to have backups. At least if they all start, you can give away extras to friends and family to grow in their yards!

Lighting and Temperature

Ensuring your plants have the right amount of light and a regulated temperature is essential for proper germination. To begin, let's examine light options for your seeds.

Are you planning on sprouting your seeds with natural sunlight or with an indoor light? It is possible to use sunlight and supplement your home lighting. Still, there are things to consider, like how some seeds prefer darkness to germinate. If some of your plants need shade, consider adding a cover to the container in place of lighting.

Growing in Natural Light

Were you planning on using natural light for at least part of your germination? Make sure you have a south-facing window exposing them to indirect sunlight. Direct sunlight may be too much in the early stages of growth. 

Why a south-facing window? In the northern hemisphere, this is the side that will receive the most sunlight and, as such, is the favorite spot for most plants. Aim to provide them a cycle of approximately 15-hours of light and 9-hours of darkness, but every plant is different. Schedule your supplemental lights to come on a few hours before sunrise and turn off a few hours after sunset.

Also, as your seeds germinate and begin to sprout their first leaves, be sure to turn the tray often. Plants like to reach towards the light (i.e., sun, lamp, etc.), and by rotating the container daily, the stem develops evenly. The last thing you want is vegetables with stems so weak they struggle to hold the weight of their produce.

Growing Under Fluorescent Lights

When growing under fluorescent lights, aim to keep the bulb a few inches above the tops of the seeds and seedlings. As the plant grows, it will reach up towards the light above it. If it is too far away, the plant will devote more time reaching for the lightbulb than developing a sturdy base. The resulting leggy plant will still produce, though weakly.

Please note that keeping plants too close to high power lights (i.e., High-Pressure Sodium or Metal Halide) can also be detrimental. The heat produced by these lamps may be too much for the tender seeds. The goal should be to keep your seeds warm but not too hot. Aim for a daytime temperature between 65-75F (18-24C). Don't let the night time temperatures fall below 55F (13C). An excellent way to maintain these temperatures is to place a heating pad under the tray.

Get Germinating

With your seeds in their trays, you can set up a corner of a relatively unused room for germination. With no windows that can provide the necessary light, you plan on using a fluorescent tube light. After placing your tomatoes, you lower the light-fixture until it is inches from the surface. Placing your hand between the bulb and the seeds, you can feel the heat against your skin. You decide to raise your light another inch and feel confident that the temperature won't hurt your developing seedlings.

Water and Feeding

Proper watering at the seed and seedling stage is essential. When watering, moisten the medium. Make sure not to overwater at this stage. You can use a spray bottle to mist the seeds. If possible, place your container into a basin of water and allow the growing medium to wick up moisture from the holes at the bottom. Top watering can result in the seeds being washed to the side or even out of the tray.

Are you looking to cut down on watering? You can buy a small plastic dome to put over your tray or build one yourself. The University of Missouri recommends that after watering your seeds, you cover the container with plastic. The moisture caught by the plastic will create an ideal miniature greenhouse for your plants until they sprout. You're going to want to check the moisture level of the soil every one or two days as a precaution. Still, the plastic method mentioned above should be enough to maintain your seed to seedling stage.

At this stage, the newly sprouted seedlings won't need much additional nutrients. Every plant will have a different feeding schedule. For optimal feeding strategies, refer to the plant packages. For now, phosphorus and potassium are necessary at this stage. They promote healthy root growth. Nitrogen is still essential, but it supports the overall growth of the plant. Too much nitrogen at this stage can produce a leggy plant with a weak root system.

Care For Your New Garden

With your tomatoes in position, you give them a quick mist with a water bottle before laying a layer of plastic over them. This stage is slow, and new growers are guilty of walking into a room and checking to see if the seeds have started growing in the last hour. Be sure to let your seeds sit, giving them time to sprout without disturbance, only removing the plastic barrier when you need to mist them. After a week of monitoring, you begin to notice the beginnings of green sprouts poking through the vermiculite.

At this point, your seeds are well on their way towards becoming seedlings and eventually hearty plants to produce for your home. What's next? In my next article, I will be looking at the seedling stage and how to monitor the success of your developing plants. After that, we will finish up the series with a final article on the care of mature plants.

Article by:

Tanner Sagouspe

Tanner Sagouspe has a Masters in Environmental Management and is a Permaculture Designer who promotes tackling the climate crisis at home.