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Gardening How To: Starting Seedlings Indoors

There are few things more rewarding than growing your own fruits and vegetables. It gives you a sense of accomplishment and well-being knowing that you had a hand in providing food for yourself and your family. Also, if you grow things from seeds, you know that it is 100% organic.

Why Start Seedlings Indoors?

Besides the pleasure of watching seeds sprout and grow, starting seedlings indoors give future plants a critical head start. It is easier to start seeds indoors where you can control the amount of light, heat and sun the seedlings get, thus creating hardier plants to transport outdoors. It is recommended that you start seedlings inside about eight weeks before the last scheduled day of frost in your area.

Choosing the Right Seeds

To make sure that the process is organic from seed to table, it is important to know where your seeds are coming from. Growing plants from seeds that are non-organic certified will defeat the whole purpose of organic growing. Try choosing heirloom and organic certified seeds. This is an important first step. Going to your local garden centre and buy seedlings to plant is more expensive and most garden centres will not have as much variety as the suppliers. To make sure that the seeds are viable, place them in a glass of warm water and leave overnight. If the seeds sink to the bottom they are still viable, if they float to the top, don’t plant them.

Getting Started

There are lots of containers that can be used to start your seedlings. Commercially available plant starting kits are a good start. You can also purchase biodegradable planters that will decompose as the growing season progresses. Try reusing yogurt containers, or milk jugs cut in half length-wise to reduce your waste consumption. Be sure to clean and sterilize containers to prevent mould and rot in your seedlings.

The Medium

It is important to start with a good quality, seed-starting soil with natural coir such as coconut husks to provide the right mix of slow-release nutrients and that will retain the right amount of water.


Making sure your seedlings get the right amount of water is often the most challenging thing about starting seedlings. Too little water and the seeds won’t sprout, but too much and there will be rot and your seedlings will be spindly and won’t transplant well. Start with moist soil and create a humidity dome (think greenhouse). You can either use the plastic domes that come with your container kit, or if using reusable containers, attach a plastic bag loosely over your containers.


Most people underestimate the amount of light that seedlings need. It is recommended that your seedlings get 12-16 hours of light per day! That is far more than you will get with even the sunniest south-facing window. Most garden experts recommend purchasing plant lights that can be set on timers to ensure the correct amount of light for your plants. An ideal alternative is fluorescent lighting which will achieve the same effect.


New seedlings require warmth to survive and grow. Plant heating mats provide the necessary warmth without drying out the soil. For a DIY heat pad, you can place your seedlings on a radiator, but remember if doing so, to keep an eye on the moisture level of the soil as this form of heat has a drying effect on the soil.


This one is the most often overlooked and often the most beneficial to successful seedlings. Make sure to check on your seedlings daily. When the seeds sprout, be sure to take off the greenhouse dome. As the seedlings get bigger, move them around gently with your hand to encourage strong stem growth.

Acclimate Seedlings Before Transplanting

Before transplanting seedlings into your garden, they must be acclimated to the harsher outside conditions. Gardeners call this hardening off the seedlings. This can be done over three days. Start by placing them outside for a few hours in the morning on the first day, and gradually increasing their time outdoors until they are hardy enough for transplantation.

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