Growing Plants from Seeds – It’s Easy, Fun and Economical

By Darlene Belton, Master Gardener

You’ve ordered your seeds. With luck, you’ve actually received your order. The seed shortage forecast by the Manitoba seed companies I interviewed for the January Grow Column proved right – shortages are underway. Even experienced seed-starters are waiting for early orders that in the past were always filled right away.

So, what next? I’ve checked some trusted sources, interviewed some expert gardeners*, and dredged the pit of my own experience for these suggestions to those who are new to the joy of multiplying your garden entirely to your own preferences and conditions.

*TIP: Though we are all wildly individualistic in our gardening styles, it helps to gather a small group of seed-starting friends for support, consultation and resource sharing.

First step – read the seed packets and organize them. I use a cardboard shoe box, with recipe-type file cards as separators. The packets tell you how many weeks ahead of planting out in the garden that you need to start each seed type. The general advice is to use the average date of last frost as your planting date (which in Manitoba is May 21-31) – but I, and several of my experienced friends, wait until the second week of June to plant out seedlings. Why? Pernicious late frosts and lingering cold weather in May! My gardener friends and I have noticed that, a couple of weeks later, there is no difference in size between seedlings planted in late May and those in the second week of June, because of the boost of warmer soil and night temperatures in June. So, I organize my seed packets by weeks before my June planting date and clearly label each card with the date I need to start each group.

Some seeds must be started in the garden, legumes such as peas and beans, as well as radish, carrots, corn, beets, lettuce and some flower seeds. The seed package will tell you this. Purchase a soil thermometer, as soil temperature at seed-sowing is often critical for germination. Different seeds germinate at different soil temperatures (whether planted indoors or in the ground) but most seeds germinate between 10-24C.

Be sure to purchase soil mix labeled for seed starting (not potting mix). Seed-starting mix has been sterilized to remove any pathogens but has no fertility, not needed as there are enough nutrients within the seed to sustain the sprout until its second set of leaves. Once a seedling has its second set of leaves, it requires fertilizer as it has used up its seed-based nutrients – remember that seed-starting mix has no nutrients. Fertilize only then with a well-balanced water-soluble fertilizer. NPK on the label stands for the percentage of available Nitrogen, Phosphorus, Potassium in the fertilizer, the macro nutrients most needed by plants. An easy way to remember the value of each for plants is the rhyme, ‘shoots -N, roots -P, fruits – K’. Nutrition is a great deal more complicated than that, but the rhyme helps.

The 6-cell packs designed to fit into the familiar oblong plastic trays are easiest, but they are plastic and not re-usable (non-sustainable). There are other more sustainable options, such as making your own paper containers, or using fiber ones. If you use small starter cells, when the sprouts grow too large for these, transplant each seedling into standard 3X3” (9X9 cm) containers, either made yourself from newspaper or recycled from past garden plant purchases (washed in soapy water and wiped with a 10% bleach/water solution to sterilize).

At this first transplant, rather than using sterile seed-starting mix, change to potting soil mix that contains organic matter to support growth, and fertilize every week or so, unless the mix contains fertilizer already. The 3X3” size container will take your seedlings to the final into-the-garden transplant. Some people use peat pots to later place directly into the garden (said to reduce transplant shock) but peat is a non-renewable resource and should not be used by environment-conscious gardeners. Also, I have found in our dry Prairie summers – when I tried them once some years ago – that the peat doesn’t break down as touted – even wicks moisture away, and the plants’ roots can suffer, so these are two reasons I don’t use peat containers now. Here is an excellent article on growing ‘peat-free’: Click Here

Getting it all growing.
You’ve bought your seed-starting mix and other supplies, filled, wetted and tamped down the soil in the cells, now you’re ready to plant. Lighting not needed yet! The seed packets will tell you how to sow the seed, ¼” into the soil, on the surface, etc. I usually put 2 seeds per cell, always fearing non-germination (mostly I end up with two seedlings per cell and can’t bring myself to kill the weaker one…..). Though I’ve had good success not using any heat source other than my home’s indoor temperature, I’m hearing everywhere I research of the real value of heat mats to provide bottom heat to the growing medium for faster seed germination and stronger root growth, for all seeds but especially for hot weather plants such as peppers. The Garden ProfessorsTM member, John Porter, says that even lower-end mats heat to a consistent ideal germination temperature of 22-24C, so no need for home gardeners to buy the more expensive thermostat-controlled models. I intend to purchase a basic model this year to see if the difference in seedling quality is worth the investment.

Label your sown seeds as you will never remember who’s who once they sprout! I use short wooden stakes and an indelible garden pen (regular ink runs or fades in the high-moisture environment of sprouting seeds). You can cover the seeds with the reusable clear plastic tray lids, or use recycled plastic bags. Your goal is to create high humidity until you see those first green sprout tips. However, caution is advised: “humidity + heat + pathogen = disease,” so you could be setting yourself up for problems, including ‘damping off’, a fungal infection causing seedlings to collapse. Airborne pathogens can exist in your home, especially if you have houseplants. Therefore, I remove the seed cover as soon as I see lots of green tips bursting from the soil. This is also the point at which you add light. When the seedlings have their second set of leaves, remove the heat mats, and let the soil heat drop to approximately 13C to manage growth and reduce seedling ‘legginess’. Some people use a fan to disperse moisture, circulate air, and build stem resistance/strength.

Light for seedlings is a complex topic, best to research thoroughly as you develop experience. If you have a very sunny south-facing window, you will have some success, especially for late-sown seeds as the days get longer and you will be able to get them outside for at least a few hours on warm days to supplement the light filtered through windows. There are many options for artificial light, with higher efficiency T5 (I use these) or LED lighting something to consider. However, MMGA member Janet Epp, M.G., has successfully grown thousands of seedlings in her basement using regular fluorescent lights in shop-light fixtures. Rather than move the lights away from her plants as they grow, she sits the trays on blocks to start, removing the blocks as needed to keep the fixed lights the desired 6” from the seedlings for 14-16 hours per day, and uses a fan to dissipate the extra heat of this less efficient but low-cost lighting option.

Caption: Master Gardener, Janet Epp’s seedling light system, using a regular shop light fixture and standard broad-spectrum fluorescent tube lights. Although plants especially need red, blue and green lights from the spectrum, white light contains these and is perfectly suitable for home use.

When my seedlings have been transplanted to their 3X3” containers and May has arrived, I set them outside on my deck in inexpensive ‘mini-greenhouses’ (wire shelves covered with a sturdy removable zippered plastic sheath), moving them back inside at night. They are protected from cold winds, with heat built up inside from the sun whose rays are much more intense than any grow light. I ‘harden off’ the young plants first by gradually increasing their sun exposure over several days, but nothing boosts their growth more than being outside. As they gain strength and the day warrants, I unzip their covering, removing it as the days and nights get warmer, bringing them back inside if needed, before finally transplanting them to the garden in June.

See also the HOW-TO Gardening Videos to the topic on this website under the resources tab. Access Here

Photos: Janet Epp