14 Tips for Starting Seeds Indoors

Almost everyone who gardens wonders about how to start seeds indoors at one point or another, and for good reason. Starting seeds indoors is a great way to get the jump on the gardening season by allowing you to have healthy plants ready to go as soon as the weather is warm enough. 

However, you can't just stick a seed in some dirt and call it done. There are some things you need to do to ensure your efforts are successful. So let's take a look at some tips for starting seeds indoors the right way.

seedlings growing in biodegradable pots for how to start seeds indoors post

First of all, know that gardening doesn't come naturally to me. We had a garden when I was little, but I wasn't taught much at all (I just ate the strawberries!), so it's not my forte. Thankfully, I'm a pretty good researcher, and I have some very experienced friends helping me out. So let's learn and do this gardening thing together!

Benefits of Starting Seeds Indoors

Starting seeds indoors gives you several advantages to your garden that you can't get any other way. When you start seeds indoors, you'll spend less money, extend your growing season, produce heartier plants, and in general, have a more productive harvest. Whether you are doing regular, raised bed, straw bed or lasagna gardening, starting seeds indoors can give you are real leg up on the season in many ways.

Save Money

Although you'll need a few basic supplies for indoor seed starting, it's still far less expensive than buying plants to put in your garden. You can often get a whole packet of seeds (sometimes that means HUNDREDS of seeds) for the same price as one small plant.

Of course, to save the most money, you ideally should grow your plants from seeds saved from the previous year's garden. However, even if you end up buying seeds, it is still far cheaper than buying seedlings or established plants.

Of course, getting free plants is the cheapest method of all, and there are even MORE money saving tips in this post on starting seeds on a budget.

Healthier Plants

In general, starting seeds indoors leads to healthier plants. That's because you have pretty much complete control over what your plants come into contact with from start to finish when you start your plants from seed.

Even the most meticulous, privately-owned garden center can't completely keep disease out of their stock. And let's face it, the big box garden centers aren't exactly known for the health of their plants. When you learn how to start seeds indoors, you are setting your plants and yourself up for success.

Earlier Harvest

Starting seeds indoors allows you to start growing when the outside weather is cooler, so you can harvest the fruits of your labor sooner. You can also try planting some of these fastest growing vegetables to speed things up even more. If you're going to be planting some vegetables that grow in shade, starting seeds indoors will help you get more yield faster.

Extended Growing Season

When you start your seeds indoors, you can start them earlier than you otherwise can, typically resulting in larger plants for transplanting, and a longer growing season. If you live in an area where your growing season is short, this can be a huge boon, allowing you to grow some plants that you otherwise could not. 

A More Productive Harvest

When you put healthier plants and a longer growing season together, you get a more productive harvest. Plants that get a head start in your beds have a longer time to produce their fruits and vegetables.

In addition, since starting your own seeds almost always leads to healthier plants than those bought from a greenhouse, that should lead to more productive plants.

More Variety

Starting with seeds instead of plants gives you greater plant variety. You can easily buy more types of seeds than you can buy plants or seedlings.

Satisfaction

There's a lot to be said for knowing you did it yourself--from start to finish. And there's something truly amazing about seeing tiny seeds turn into a hopefully huge harvest.

collage of seedlings growing in biodegradable pots and trays for post about starting seeds indoors

How to Start Seeds Indoors

Note that there are some seeds that better sown outdoors rather than indoors. This post on sowing seeds indoors vs. outdoors includes a list of plants that really should almost never be started indoors. So that's a good place to start in addition to following these indoor seed starting tips.

Dedicated Place

First and foremost, you're going to need an area to get your seeds growing. While some seeds require sunlight to germinate, most just needs moist soil and warmth, so start by picking out a spot with plenty of space for the seeds you would like to grow.

Quality Seed

Always start with quality seed (here's one good quality seed company to consider). Saved seeds from plants that have performed exceptionally well the prior season and high-quality seeds from a reputable seed source are the way to go. Never cheap out on your seeds. Start with quality seeds and you're more like to end up with quality plants.

Use Quality Starting Mix

One of the biggest mistakes people make when starting seeds indoors is buying potting soil or garden soil to use for their seeds. Potting soil and garden soil are too heavy and can often have disease spores in the soil.

Some say you should sterilize your soil, while other say that this is a big mistake. 

I personally think it makes sense to use quality seed mix (I've heard good things about this seed mix and this seed mix as well) and leave the beneficial microbes as they should be. 

Pre-moisten your seed starting mix before filling your containers with it. Ideally, the mix should be moist but not soggy--kind of like brownie mix. Fill your containers with the mix, pressing the mix lightly down to remove air pockets.

Use the Right Containers

When starting seeds indoors, it's crucial to use the right containers. Use plastic six-packs and flats for starting your seeds. These have holes in the bottom that allow for proper drainage. You can also use empty single-serve yogurt containers, the bottoms of water bottles, and the like and simply poke holes in the bottom.

Proper Depth is Key

Always check your package for planting depth instructions. All seed packages will have a recommended depth for planting. While you don't have to necessarily measure every time you place a seed, it's important to never plant past the recommended depth.

Plant Multiple Seeds

Rather than using those fancy single-seed starting packs, use gardening pots and flats like the ones mentioned above and plant four to five seeds in each one. Choose the healthiest seedlings and discard the rest.

Keep Seeds Warm

Warmth is key for seed germination. After you've planted, find a warm spot for your seeds. The top of your fridge or near a radiator or heating vent are good choices. You can also buy heating mats for your seed trays.

Keep Seeds Moist

This is key as well. Think of your starter mix as a sponge more than soil. You want your "sponge" to be consistently damp without being saturated. You want your seeds to have plenty of water to germinate without leading to rot.

Seedlings Need Sunlight

After your seeds sprout, move them to a sunny window that gets plenty of light during the day. For the best results, however,  fluorescent grow lamps should lead to sturdier seedlings.

Keep Seedlings Cool

While seeds require warmth to germinate, you'll get the best growth results for your seedlings in a cooler area. Temperatures in the high 60s make for sturdier seedlings. Too much warmth leads to leggy plants that aren't as hardy.

One of the best combinations for producing super healthy plants is moving seedling to a garage or basement and keeping them under a fluorescent light for 16 hours a day.

Don't Forget to Feed

Most seed starting mixes have little nutritional value to plants. In the beginning, your sproutlings will draw nutrients from the seed's endosperm, but after that, they'll need food.

Use an organic, half-strength fertilizer once your seedling has produced its second set of leaves, or its "true leaves". Liquid fertilizers are easiest to dilute and administer. Just be sure to follow the label instructions for best results.

Thin Your Seeds

Once your seedlings have one or two sets of leaves, it's time to thin them. Starting seeds indoors is all about survival of the fittest. Choose the healthiest seedling from each pot, and discard the rest.

Transplanting to Larger Containers

Sometimes you will need to transplant seedlings to larger pots even before you harden off your plants to move them to their permanent spot in the garden. Some plants like tomatoes, for example, require being moved to a larger container before they're ready to be planted in the garden. You'll know it's time to move the plants because they'll either be root-bound or will require constant watering.

Plastic party cups with a few holes poked in the bottom make ideal containers. Before transplanting, water your seedlings well to help keep the soil around the roots and prevent transplant shock. Use good quality organic potting mix and pre-moisten it just like you deed when starting seeds indoors.

Fill the plastic cups partway, leaving enough room for your plant's rootball to sit about a half an inch below the rim of the cup. The only exception to this is tomatoes. When transplanting tomatoes, plant as much of the plant as possible. It will grow new roots along the submerged portion of the stem.

Watch for Pests and Disease

Keeping a close watch on your plants will help you keep them healthy and pest-free. If you notice a problem, try to act quickly to nip it in the bud. Since there are no natural predators for plant pests indoors, things can spread quickly and even transfer to other plants in your home.

Here are some tips to prevent pest and disease issues:

  • Avoid overwatering to prevent root rot
  • If you notice any signs of insects, use an herbicide (as natural as possible) to eradicate them fast. 
  • If you notice possible disease signs, do your research and if it looks like something that will spread, it's best to compost the plant to avoid transferring the problem to other seedlings.

Let's Get Gardening!

Hopefully with the steps above you will be able to start a fruitful garden of your own, or improve on your gardening skills with a better garden year after year.

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