How to Start the Best Seedlings Indoors for Your Garden

How to Start the Best Seedlings Indoors for Your Garden

How to Start the Best Seedlings Indoors!

This article provides a complete tutorial on how to start seedlings for your garden. Starting your own seeds indoors is a great way to b more self-reliant and save money on your garden!

When you start seedlings indoors you have complete control over the fertilizers, pesticides, and soil used. Starting from seeds also gives you a huge number of varieties to choose from. Nurseries often have 2 or 3 varieties of tomato seedlings to purchase. You’ll be amazed at all of the varieties of tomato seeds there are!

You also have complete control over when you start seedlings. This gives you the option of starting cool-season crops early enough to get an extra harvest in the spring!

Learn How to Set Up a Seed Starting Calendar!

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My Background in Seed Starting

I’ve been gardening since I was 3…I still remember helping my Dad plant bean seeds in our garden as a little tyke. I began growing my own seedlings in windowsills in the spring then created a homemade seed starting set up that has served me very well.

I also know what it takes to start seedlings on a commercial scale from my education in horticulture. In greenhouse management and annual production classes we were required to grow flower and vegetable starts according to greenhouse industry standards. I learned a lot about starting seeds indoors for your garden!

Mary's Heirloom Seeds offers a wide variety of seeds... Start the Best Seedlings Indoors for Your Garden

Why Start Your Own Seedlings?

  • Save money
  • Control over pesticides and fertilizers
  • Access to more varieties
  • Green therapy!
  • Learn a new skill

Save Money By Starting Your Own Seeds Indoors

The cost of greenhouse production is enormous. Besides the investment in the facility itself, there are costs for heating, cooling, watering, chemical applications, labor, growing medium, seeds, containers, and transportation.

Once the flats reach the retail nursery they still need to be cared for – more labor. Plus, everyone wants to make a profit off those little plants. Of course, you pay for all of that when you buy seedlings.

A popular non-organic fertilizer...I don't think this color occurs in nature.
A popular non-organic fertilizer…I don’t think this color occurs in nature.

Control Over Fertilizer & Pesticide Application

In my annual production class, I was surprised at the volume of non-organic chemical applications used to produce those gorgeous flats of veggies. There are insecticides, fungicides, miticides, fertilizers, and hormones for regulating growth.

Some of the insecticides applied are systemic, which means that bees and butterflies are poisoned by the nectar from treated plants. Systemic insecticides are transported through the entire plant.

I felt a little sick thinking about all of the non-organic chemicals applied to all those starts I’ve tucked into my ‘organic’ garden over the years.

Seed starting trays

Choosing Containers for Starting Seeds

There are many kinds of containers for starting your little seedlings. It's important to make sure they are clean (sanitize with mild bleach solution) and have drainage holes.

You can use peat pots or pellets that can be planted along with the seedling. Mini greenhouse kits are also available. They look like the flats seedlings come in and include a transparent lid for retaining moisture.

Recycled containers (plastic yogurt containers, the bottom half of milk cartons, plastic or paper cups, even newspaper pots) work great as long as they are clean and excess water can drain from the bottom. You can also make plantable newspaper pots with a handy form!

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Pepper plants under shop lights. One cool and one warm bulb provides a broad spectrum of light.
Pepper plants under shop lights. One cool and one warm bulb provides a broad spectrum of light.

How to Provide Light for Seed Starting

You can start your seedlings in a sunny windowsill, but I would start them a bit closer to your last frost date and be prepared to turn them every day to keep them from bending toward the light too much. They won't be as strong as seedlings started under lights, so if you are planning to start seeds indoors every year I recommend setting up a seed starting station with grow lights.

I have a  spot in my basement dedicated to starting seeds. A plastic shelving unit gives me room to start up to 10 flats of plants. Each shelf has a 4 foot long shop light hung from the shelf above by wires, allowing me to adjust the lights up and down.

The shop lights each have 1 warm white and 1 cool white bulb to provide a broad spectrum of light for the baby plants. This is much less expensive than the grow lights made specifically for this purpose, but they work well.

I've had good results with my seed starting set up for many years and it didn't cost a lot to set up. It is advisable to replace fluorescent bulbs every year or 2 for the best results. For a non-toxic alternative to fluorescent bulbs that last longer and use less energy, consider purchasing these LED bulbs in the natural sunlight option.

Set up your shop lights on a timer so that the lights will come on for 12 hours a day. You don't want to have the lights on 24/7. For some plants that would be ok, but for plants that are sensitive to day length, the sudden change when you move them outside will trigger flowering before they are ready.

Seedling Heat Mats

I've read all kinds of home do-it-yourself set ups for providing bottom heat for the germinating seeds. All I can say is, please be careful! Make sure you aren't creating an electrical hazard with a rigged up contraption.

I purchased 2 seed starting mats years ago and they are still in great shape. I've saved many times the purchase price by starting my own seeds with these mats, so I have no complaints.

Make sure that the soil isn't too hot for proper germination. Most seeds germinate best in the 65-85 F range. Check out this chart for optimal temps for different seed types.

Baby seedlings are a sight for sore eyes.
Baby seedlings are a sight for sore eyes.

How to Plant Seeds Indoors

Now that you have all of your seed starting supplies and your area is set up, you're ready to go!

Start by moistening the growing medium so it is damp, not soaking wet. Scoop it into your containers so they are about 3/4 full or so.

Check the seed packets to see how deep to plant the seeds. Very fine seed (petunia, lettuce) germinates best if scattered on the surface, then press seed into the soil or cover with a fine dusting of soil. Larger seeds should be covered at about the same depth as the size of the seed.

If you have small pots that are the right size for one seedling, I suggest putting 2 seeds in. If they both germinate, pinch off the runt.

You can also start your seeds in a nursery container (plastic trays with drainage holes), then re-plant them (called 'pricking out') into individual pots after germination.

Water the seeds in lightly and cover with clear plastic to retain moisture. Be sure to label your containers with the crop and planting date.

Check each day for germination and moisture levels. Don't let the top of the soil dry out.

As soon as the seed begins to germinate, remove the plastic. You'll need to check more often for moisture to make sure the delicate little sprouts don't dry out and die.

Some seeds take longer to germinate than others. Check the seed packet for the length of germination so you'll have an idea of what to expect. See the note at the end of this article for instructions on testing seed viability.

Bottom heat helps with germination. Don't let soild stay wet.
Bottom heat helps with germination. Don't let soild stay wet.

Growing Tips

If possible, set up a small fan to oscillate over your little seedlings. You'll need to water a bit more often, but the air circulation will stimulate stronger stem growth and will also help prevent damping-off.

Damping-off is a fungal infection that causes the little plant to topple over and die. Closer inspection will reveal a pinched looking stem just above the soil line. This disease is more common when the growing medium is kept too damp, too cool, or a non-sterile soil mix is used.

If it happens, toss them out and start over with new growing medium and freshly sterilized pots. Be sure to allow the soil surface to dry between waterings. Using a mister bottle will help prevent overwatering and mimic dew settling on the little plants.

As they grow, lightly brush your hand over the tops of the seedlings 2 or 3 times a day to help them grow stronger in anticipation of their move to the great outdoors.

Organic fertilizer is less likely to burn tender roots.
Organic fertilizer is less likely to burn tender roots.

How to Fertilize Seedlings

If you used a growing medium that contains a timed release fertilizer for seedlings, you won't need to provide any nutrients until they are transplanted to the garden. Otherwise, use a very weak solution of kelp or fish emulsion to water them once a week or so.

Don't overdo it! It is very possible to 'love' your seedlings too much and burn their tender roots with too much nitrogen. Most fertilizer containers will give instructions for use on seedlings.

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Cabbage seedling just transplanted to the garden.
Cabbage seedling just transplanted to the garden.

Hardening Off Seedlings

As the date of your average last frost approaches, you'll want to harden off the seedlings to get them ready for life in the great outdoors. To harden off your babies properly, you'll want to start taking them outside on warm, mild days for a few minutes to a half hour.

Don't forget them overnight or they will die and you'll be off to the nursery to buy your starts! Don't put them out in full sun or windy spots. They are used to the comfort of the indoors and will be very tender at first.

Slowly increase the amount of time they stay outside over a week or two until they've grown sturdy enough to withstand the rigors of being out all day.

Continue to move them indoors or to a protected spot in your garage or a cold frame for the nights until you are sure that the danger of frost has passed.

Cover them for the first few nights. They still aren't used to the cooler temperature of a spring night and you don't want to damage them.

Rows of cabbages in my Dad's garden.
Rows of cabbages in my Dad's garden.

How to Transplant Seedlings in Your Garden

When the seedlings are ready to transplant to the garden, and the chance of frost has passed, make sure their new home is ready for them. Till the soil and prepare the bed. Water them well about an hour before transplanting so they'll have time to soak up all they need.

If your little plants have become root-bound in their containers, gently loosen the root ball so the roots will grow out instead of in a tight ball. This will increase the amount of water and nutrients they will absorb as the roots grow.

Plant at the same depth as they were in their pots. Tomatoes are one exception...they can be planted up to the newest set of leaves. Pinch off lower leaves and roots will form along the stems to get them off to a strong start.

If possible, cover each seedling with row cover or shade cloth to protect them while they adjust. Don't cover them with anything that will heat up in the sunlight. Glass and black fabric may cook them, even on an overcast day.

If you transplant in the evening, cover to protect them from the cool night air. Paper bags work well if they are staked into place. Be sure to water the plants well as their roots have been disturbed and won't be able to absorb as much for a few days.

After a couple of weeks, the plant have really started to take off!
After a couple of weeks, the plant have really started to take off!

Don't be Surprised if You Are Hooked!

Starting your own flower and vegetable seedlings is a rewarding and fun process! Once you've got the hang of it, you'll wonder why you ever bought starts from the nursery. are officially addicted to gardening!

Testing Germination Rates

If your seeds are old, you may want to test their viability, or ability to germinate. Place 10 seeds on a damp paper towel and fold it over. Place the paper towel in a plastic bag and label it with the date and seed variety. Leave in a warm place and check every day.

Some seeds germinate quickly, like lettuce and cabbage. Some seeds, such as peppers, take longer to germinate. If the seeds have not germinated consistently after 2 weeks, purchase fresh seed to replace them.

Some seeds, such as parsnips, do not germinate well after just a year. Others will keep for long periods with no problem.

Pickled peppers
Pickled peppers

Hints for Growing Perfect Peppers

Pepper plants like heat. You will want to wait a couple of weeks or so after your average last frost date to transplant them into the garden. Warm the soil up with black plastic or the black landscape fabric for a few days before planting peppers. Cover them if night time temps are expected to drop down below 60 F.

My Dad swears by watering his pepper plants with a teaspoon or two of Epsom salts per gallon of water when they begin to blossom. I haven't tried this, but I do find that a good, organic tomato fertilizer does wonders for pepper production.

The Epsom salts help provide calcium, necessary to prevent blossom end rot. Another hint for preventing this problem is to keep the soil evenly moist.

Do you have any tips, hints, or tricks for starting your seedlings indoors? Leave a comment!

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