How to Start Seeds Indoors

How to Start Seeds Indoors

As a gardener, the benefits of starting your own plants from seed is nearly endless. The joy of watching a small seed that your nourish and coax into becoming a full grown plant is rewarding, educational, and empowering.

When you plant from seeds you’re not just limited to what plants are for sale at your local nursery, the entire seed catalogue becomes open to you. You can plant nearly whatever you want and whenever you choose to. And when you choose to plant your seeds earlier in the year indoors you’ll be rewarded with earlier blooms and harvests in the spring and summer. Those plants will also be stronger and more well adapted to your specific climate. All it takes is a few basic guidelines to master this cornerstone skill of gardening.

The Most Important Part - The Seeds!
In order to successfully start any seeds indoors you must start with good quality seeds. Make sure your seeds were packaged for the current growing season. If they weren’t, make sure they have been stored in a cool, dry and dark place. Seeds that have been exposed to heat, moisture and light won't be as vigorous.

The reason this is so important is because your seeds are actually alive! In fact, those small, brown, dried little guys are actually breathing and absorbing moisture from the air. Because inside that hard outer shell is a small plant embryo, living and waiting. Waiting for you to give it just what it needs to spring to life!

The Planning Stage
Before you even purchase your seeds, it’s best to take some time and plan out what you want to grow this year. First, figure out your area’s average last frost date as many young plants won’t want to be planted outside until after this date. Once you have that date, work backwards from there, starting plants indoors the following number of weeks before that date:

# of weeks before last Frost Date
6-8 weeks
8-12 weeks
4-6 weeks
4-6 weeks
4-6 weeks
2-4 weeks

It’s also a good idea to think about staggering some of your sowings, using a method called succession planting. It’s very simple but makes all the difference. Instead of planting all of your lettuce seeds at the beginning of the season, break it up into a few sowings spread out by 2-4 weeks. That way you’ll have just the right amount of lettuce over a long season instead of way too much lettuce all at once! This method works great with tons of crops (lettuce, radishes, broccoli, cauliflower, beets, carrots, turnips, etc).

Choosing the Containers and Soil Mix
Nearly any type of household container can be used for starting seeds: yogurt cups, egg cartons, milk jugs, water bottles, toilet paper rolls, you name it! In addition to these DIY options, plenty of store bought seed starting kits are available that contain nearly everything you need. Regardless of what you use you’ll want your container to be around two inches deep and have adequate drainage.

Though just as many options seem to be available for the seed starting soil, this choice is a little more important. The mix in which your seeds are first grown is what will provide nutrients, water, air and warmth to your young seedlings, making it a critical part of the process.

Don’t use regular garden soil from outdoor. It is typically too dense, doesn’t drain well and will often harbor diseases that the young seedlings can’t fight off. It is possible to make your own mix from different ratios of soilless components such as peat moss, vermiculite, perlite, coconut fiber and others.

We recommend sticking with a store bought, pre-made seed starting mixture. A good mix will be of a fine yet fluffy texture that holds moisture well but also drains. Some mixes come with nutrients included, others require you to add your own. Take note of which you are using.

Planting the Seeds
Time to get your hands dirty and starting planting! Fill your chosen containers with the seed starting mix to the top. Make a small indentation in the soil for your seed. The depth of this hole is determined by the size of the seed. The ideal planting depth is 2-3 the width of the seed. Tomato seeds are pretty small, usually about ⅛ inch, meaning they should be planting about ¼ inch. Bush bean seeds are pretty large however, sometimes nearly ½ inch wide, meaning they should be planted much deeper to about 1.5 inches.

In each hole it’s a good idea to plant at least two seeds. That way if one of them doesn’t germinate you’ve got the other one right next to it as a backup. If they both germinate it’s best to remove the smaller or weaker looking seedling.

Cover the seeds with just enough soil and very gently compress the mixture. By very gently compressing the soil you are creating proper contact between the seed and soil, which is critical in order for the seed to absorb water from the containers. With a gentle flow, thoroughly water the soil until it begins to drip out of the bottom of your container.

Providing Warmth, Light and Moisture
Possibly the most important part of coaxing your seeds to break through their outer shell and begin to sprout is providing enough warmth. Every seed has a different temperature range that it prefers for germination, and generally that temperature is warmer than what it prefers later when it’s a seedling. A good soil temperature range for most seeds to germinate is 75 to 90º. Even though it might be 75º in your home, the moist soil that your seeds are in will be cooler than the air temperature.

There are plenty of warm spots around your home that make for a good germination station. Above refrigerators or other heat producing appliances, near a south facing window, close to a heating vent or hot water heater. Heat producing seedling mats are also widely available and provide a constant and reliable source of heat.

You can also create a small greenhouse around your containers by placing them inside a transparent bag or covering the top with plastic stretch wrap. Place the covered containers near a sunny window and the light will create heat under the plastic while also keeping the soil moist. Once the seeds have germinate remove the plastic to allow proper airflow for the seedlings.

Though most seeds don’t require light to germinate, once they do begin to sprout up through the soil it then becomes essential to provide them with enough light. Only south facing windows that receive all day sun will have enough light to provide for your seedlings. If this isn’t an option then you can purchase a number of styles of grow lights that will work just fine. Florescent shop lights are a favorite among many gardeners. Use one cool colored light bulb and one warm colored light bulb in the fixture and hand it within a couple inches of your seedlings.

The initial thorough watering you did when you first sowed your seeds should have been enough to get them through to germination. Once the seedlings begin to grow though they will require more and more water. The more leaves they have the quicker they will transpire water out of the soil. It’s important to keep the soil moist but not soaking wet. Plant roots need air just as much as they need water to survive. Allow the soil to dry slightly between waterings, and then water to the point that it begins to drip out the bottom of your container.

Continued Care and Planting Out
It’s a good idea to check on your seedlings every day. Make a habit every morning of observing them, taking a few notes even, and watering if needed. As they grow larger they might require potting up, or being transplanted into a slightly larger container. If you notice the soil drying out very quickly or roots growing out of the bottom of their containers then they most likely need more room.

When the time has come to transplant your seedlings into the garden it can be very exciting. You’ll want to take a few precautions to make sure all your hard work doesn’t go to waste at this point. Instead of moving the young transplants directly into the ground it’s a good idea to leave them in their containers and move them to a slightly shaded area of your yard for a couple days first. This allows them to acclimate to the outdoor weather and sunlight.

When it’s time to put them in the soil, pop them out of their containers and loosen up their roots a bit. This disturbing of the roots encourages them to regrow outward into their new garden soil. Water the new transplant in thoroughly and enjoy!