How to Start Vegetable Seeds Indoors

Tips and Tricks for Starting Seeds Indoors

There are numerous benefits to starting seeds indoors. You have a wide amount of seed varieties to choose from, you know what products are going into your food and flowers, and you save money from purchasing seeds instead of plants. If this is your first time starting seeds, keep it simple and don’t overwhelm yourself by purchasing an overabundance of them. Think about what foods you and your family eat the most and start by buying seeds for them. 

Why start seeds indoors?

Some varieties are best started indoors because you have complete control over their growing conditions. Starting seeds indoors also extends your gardening season. As a result, you can grow varieties that require longer growing times than your area’s natural growing season allows.

When is the correct time to start my seeds indoors?

Use your average last frost date as a guideline for when you should begin to sow your seeds. This is identified as the last day in spring when there is less than a 50% chance that a frost will occur. Most seed packets will tell you to “Start indoors X weeks before last frost”. This is also generally known as your USDA Growing Zone. 
Seed packets will also list dates by zone. You can identify your zone here. It’s also helpful to know your average first fall frost date so you can determine the number of days in your growing season as well as plan your summer and fall sowings.

Here is a general guideline on how long before your average last frost date to start indoors:

How do I start my seeds indoors?

Containers and Labeling

Almost anything can be used as a container to start seeds, including milk, yogurt cups, and plastic trays.  If you are reusing a container, make sure you clean and sanitize it before planting seeds inside it. Don’t forget to label your seeds as you sow. Posting Garden Tower® reusable plant marking stakes or simply labeling containers with paint markers both work well.

Medium

A high-quality seed-starting mix, or medium, is loose and lightweight. Make sure you thoroughly moisten the medium before filling your container. It should hold the moisture while being free from sticks and bark. Avoid potting soil mixes, which can be too heavy for tiny seeds, or soil from your garden that may introduce insects, weeds, or diseases. Garden Tower® Peat Pellets serve as a perfect medium, as there is no netting around them, or anything that needs to break down. 

Moisture

Covering your containers with a clear lid or plastic wrap will help retain moisture and increase humidity during germination. After your seedlings emerge, remove the cover. Misting them with a spray bottle, or bottom watering them (adding water to the drainage tray) will keep the medium moist without disturbing young seedlings. Check the moisture regularly to prevent seeds and seedlings from drying out or from sitting in standing water. Our Seed Starting Green house offers adjustable ventilation to assist with this.

Light

To achieve optimum growth, seedlings need at least 14 hours of light per day. Even your sunniest window may not supply enough light to grow strong plants. A shop light with cool-white fluorescent bulbs or a mix of cool-white and warm-white bulbs placed 1”–2” above the seedlings will provide sufficient sunlight for them. Make sure you use a timer that is set to turn on and off automatically.

Temperature

Optimal temperatures for seed germination varies. Seed packet sowing instructions will indicate if they are temperature-specific. Once the seeds germinate, room temperatures of 70º–75ºF will help most seedlings grow best. Generally, frost-sensitive plants such as tomatoes, eggplants, and peppers appreciate warmer soil conditions and may benefit from the use of a Garden Tower® seedling heat mat when sown indoors.

Circulation

Air circulation around seedlings can help prevent diseases while strengthening seedlings. A fan on a low setting will create adequate airflow. Avoid aiming the fan directly at the soil, as it can cause rapid drying. Our 2" dome offer adjustable ventilation to assist with this.

Fertilizer

If your seed starting mix does not contain nutrients, add a diluted amount of slow-release, organic, balanced fertilizer to the medium or a liquid formula once seedlings have true leaves. “Balanced” fertilizers have equal amounts of nitrogen, phosphorous, and potassium represented, respectively, as numbers with dashes between them (e.g. 20-20-20). Check the label for instructions on diluting the fertilizer, as well as the recommended frequency and rate to mix for seedlings and transplants. 

Hardening off

This is a 7 to 10 day process for acclimating plants that were started indoors to outdoor conditions. This process reduces transplant stress and the chance of sunburn, which negatively impacts overall performance and yield.
Start by placing plants in a protected, shady area, progressing to more sun (for sun-loving varieties) over 7 to 10 days. Bring plants in at night if temperatures drop below 45°F. After 7 to 10 days, plants will be ready for transplanting. Before transplanting, consider fertilizing them with seaweed or kelp to further reduce transplant stress. Transplant on a calm, cloudy day in the evening, or use row covers to buffer wind, sun, and temperature swings. Most warm-season plants perform best when transplanted in soils over 45°F.

Starting seeds indoors is a fun and rewarding process. With our Garden Tower® products, you can get started immediately! But be warned, it can be challenging to not grow addicted to it after the first batch!