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Seed Starting

In the dark, short days of winter, it is easy to daydream about the sunny days of spring and summer when your yard or garden are filled with blooming flowers and fresh produce ripe for the picking. Through food preservation practices of canning or freezing, you can get the taste of the fresh produce, but there really is nothing like going and picking a fresh tomato or frying up fresh squash right out of the garden. Thankfully, we can bring some of the joy of getting garden plants ready indoors even if the snow is still falling outside in early spring.

All plants start somewhere. Some plants do fine if you sow seed directly into your garden, while others germinate better in a controlled environment. This is where human intervention can come into play, and spring can start a few weeks early – in your own home.

Seed Selection

One of the first steps to take when starting seeds will be to select your seeds. Select varieties that will meet the needs of your gardening goals. It also is important to consider the number of growing days for your area. Some varieties can be started outside, while others should be started inside so that you can have a bountiful harvest before the first frost in the fall. Furthermore, you can sow seeds mid-summer to have transplants for fall crops, like Brussels sprouts, broccoli or cabbage. Also, think about the source of your seeds. Be sure to purchase seeds from reputable suppliers. If you already have seed from the last season, it can be used if it was stored correctly. If you choose to store leftover seeds, keep them in an airtight container in a cool, dry space, or they can be frozen.

Container Selection

Seed sprouts in a cell tray.

There are several options available when selecting a container to sow your seeds in. If you have a more restrictive budget or plan to start a few plants, consider using old butter or yogurt containers. Thoroughly wash the containers and punch holes in the bottom for drainage.

However, if you plan on having several different varieties or want to start several seeds, consider using solid trays or plug trays. There are benefits to both. Solid trays, also called flats, are sturdy and allow you to sow as many seeds as you please. Plug trays have individual planting cells, are useful if you want to start 10 to 20 seeds of each vegetable or variety, and allow you to save space. They also are easy to transplant out of. The biggest disadvantage of plug trays is that each plant will have a more limited amount of growing medium to grow in, which also will restrict water as the plant grows.

You may want to consider using peat pots or other biodegradable pots that can make transplanting simple since you will not need to remove the transplant from the container. However, these pots tend to lose water more rapidly.

When choosing a container, consider the size of the plant. If the plant will be large and grows fast or can suffer if the roots are disturbed, you may want to use a larger container, such as a cell pack or yogurt cup.

When it comes to growing medium, it is important that you use a germination mix or a soilless potting mix rather than soil from your garden. This helps keep the tender seedlings healthy and free of diseases that can come from garden soil. You have several options for potting mix and can even mix your own. It is important to note that you should not plant seeds in a waterlogged mix or too dry of a mix. If you can wring a steady stream of water out of the mix, it’s too wet and you’ll need to add more dry mix.

Many times, we consider the moisture level of our potting mix, but sometimes forget to consider soil temperature. When you purchase your seeds, the seed packet will indicate the optimal soil temperature range for germination. A soil thermometer can provide more information on the temperature of your soil and help you avoid the guessing game. Some seedlings will do fine with cooler soil, while others, like peppers, may need bottom heat to germinate. You can easily provide bottom heat by placing them on top of the refrigerator or using a heat mat.

Sowing Seeds

Seed sprouts in a cell tray.

Now that you have your seeds, container and planting medium, it’s time to sow! But wait, you might not have considered timing. Some seeds can take a while to germinate, while others can germinate in just a few days. This is when you’ll need to consider your growing conditions and what you’re seeding. Many seed companies have calculators or guides to help you decide when to start seeds. Generally, most seed packs will say when to seed indoors, so check the back of the seed packet to find out when to seed prior to transplanting outside. Some other factors to consider when determining when to start seeds:

  • When is your first frost-free day?
  • What are the days to maturity?

Seeding and Transplant Age for Garden Crops
Vegetable Transplant age (weeks) Seed starting date for gardens
Broccoli 6 to 8 February to March or July
Cabbage 6 to 8 February to March or July
Cauliflower 6 to 8 February to March
Cucumber 3 to 4 April 
Lettuce 5 to 6 January to May
Peppers 8 March
Pumpkins 3 to 4 May to June
Squash 2 to 3 May to June
Tomatoes 6 to 8 March to May
Watermelon 4 to 6 April
Herb Transplant age (weeks) Seed starting date for gardens
Basil 6 March to April
Oregano 8 to 10 March
Rosemary 10 to 12 February to March
Parsley 9 to 10 January to February
Thyme 8 to 10 February to March
Flowers Transplant age (weeks) Seed starting date for gardens
Impatiens 8 to 10 March 10
Marigold 6 to 8 March to April
Snapdragon 8 to 10 February to March
Zinnia 4 April to May

When the time to plant arrives, fill the containers with the grow medium of your choice, be sure that it is moist and then, it is ready for planting A general rule of thumb when sowing seeds is to cover them with growing medium at a depth equal to two to three times their width. However, it is better to seed too shallow than too deep to ensure better germination of the seeds. To avoid the guessing game when you are planting or harvesting, it is best that you label your seeds from the beginning. Popsicle sticks, plastic spoons or tongue depressors are all good options for labeling. You can include the date you seeded, the type of seed, variety and any other pertinent information.

Lighting

Once your seeds germinate, one of the most important keys to their success will be the amount of light that they receive before being transplanted into your garden. If you have a safe outdoor area, such as a hobby greenhouse, then you won’t have to worry. However, if you are seeding your plants inside your home, then lighting might be a challenge. Ideally, you’ll want to place your seedlings under an eastern- or south-facing window and rotate them to keep them from stretching toward the light, resulting in leggy plants.

If you do not have an ideal place in your home under a window, you may want to think about using grow lights. These lights offer an artificial form of light that acts as sunlight to provide the lighting needs for plants to photosynthesize. When using grow lights, keep them just above the plants and gradually raise the lights as the plant grows. This will help prevent etiolation (leggy plants) and will result in stocky, healthy plants ready for the garden.  

Watering

Before your seeds germinate, you shouldn’t need to water. You can increase the humidity in your container by using a clear commercial cover, bag or film. Be sure it is airtight to prevent the media from drying out before and during germination. Once the seedlings germinate, bottom-watering will help keep the soil moist without potentially damaging the tender seedling. Use a solid tray to hold the water, then place the germination container in the water.

The bigger the seedlings get, the more water they are going to require. If your seedlings are inside your home or a greenhouse, they are going to need watered once a day so that they don’t dry out. If possible, maintain a moisture level like that of the media you initially placed in your containers.

Of course, too much of a good thing can be bad. If the soil is too wet or the plants are overwatered, damping off can occur. Damping off is caused by a fungus that thrives in cool, wet soil or potting medium. It can result in a loss of a whole tray of plants and causes infected seedlings to have thin, wiry stems that usually do not survive.

Repotting and Transplanting

Some plants can stay in the container they are germinated in until they’re ready to transplant into the garden. However, if you are using small plug trays to germinate your seedlings, you’ll need to repot them. These can be “potted up” into cell packs or larger pots. If they are fast growing and it’s time to plant outside, they can go directly in the garden. It can be exciting to see plants emerge from the soil and you may question if they have enough room, but it is best if you wait to transplant until they have developed true leaves.

When you transplant your seedlings, handle them with the leaves. If you planted the seedlings in a plug tray, gently grasp the seedling at the base of the stem and gently pull from the tray, then move to the larger container that has been filled with moist potting medium.

Starting seeds indoors can be a rewarding experience as you watch the change from seed to seedling to a thriving plant, producing tasty produce or beautiful blooms. 

References

Jett, L. (n.d.). Planting Schedules for Open-Field, Low Tunnel and High Tunnel Vegetable Crops in West Virginia.

Jett, L. (n.d.). Growing Vegetable Transplants for Field and High Tunnel Production.

Seed-Starting Date Calculator. (n.d.). Retrieved January 13, 2021, from https://www.johnnyseeds.com/growers-library/seed-planting-schedule-calculator.html


Authors:  Debbie Friend, WVU Extension Agent - Braxton County; Jennifer Friend, WVU Extension Agent - Harrison County ; and Michael Shamblin, WVU Extension Agent - Clay County
Last Reviewed: April 2021