From the Ground Up Blog

How to Take Care of Your Seeds and Seedlings

How to Take Care of Your Seeds and Seedlings

How to Take Care of Your Seeds and Seedlings

Gardening season is just around the corner, which means that it’s time to start thinking about starting your seeds. Seeds are a more affordable option than plants you can find at a nursery, and you can also find unique varieties in seeds that your local nursery may not have available. However, freshly-sown seeds and seedlings require a bit of TLC and special attention. Here’re our recommendations for taking care of them.

Where to Keep Seeds

Until it’s time to plant your seeds, store them in a cool, dry space, like a drawer or seed box, away from water, light, and heat. Be very careful to keep your seeds dry, as wet seeds may sprout, even without soil or light.

The ideal temperature to store seeds at is between 32°F and 41°F, leaving many gardeners to store seeds in an airtight container in their fridge.

Starting Your Seeds

Starting seeds is simple and the right equipment can make it extremely easy. You’ll need a seed starting mix to sow your seeds into. Avoid a potting mix, garden soil, or topsoil; these soil blends can become dense and pack down on your seeds. Seed starting mix stays fluffy and helps to nurture developing roots. 

You’ll also need seed starting trays or small pots. Seed starting trays that are split into smaller cells make transplanting varieties into your garden an easy task.

Light Requirements

Seedlings need 12-16 hours of light each day, which can be provided by a south-facing window. Even with natural light, supplemental lighting is still recommended. Plants that don’t get enough light will start to stretch and become weak.

Heat Requirements

You can also promote faster growth with heating mats. Seeds sprout best when the soil is warm (check your seed packet for the ideal soil temperature for germination). Heating mats should be placed under the seed starting trays to help keep the soil warm.

You may have heard of the old trick of placing seedlings on top of the refrigerator to keep warm, but this doesn’t work with new fridges. Refrigerators used to get warm on the top but now, back of the fridge is the warmest side, leaving the top of the fridge no different than the rest of the room.

Humidity Requirements

Another way to promote healthy germination is to cover the soil and seedlings with a clear plastic cover to promote a humid environment. Many seed starting trays come with a clear top, which creates a miniature greenhouse. The soil stays warmer and more consistently moist. The top also helps to prevent the moisture from evaporating away from the soil.

Once the seedlings emerge, they are more tolerant of changes to their environment, and the cover can be removed.

How To Take Care of Seedlings After Germination

Many vegetable garden plants and herbs will emerge within a few days of sowing seeds. Some plants will emerge quickly, in as little as 2-3 days. Other plants will emerge within 7-10 days. The back of your seed packet will have information about how long it takes the seeds to germinate. Each plant and variety is different.

Once your seedlings emerge, you’ll want to nurture them to ensure they’re healthy before being moved to your garden.

How to Water Seedlings

Seedlings need soil to remain moist and warm. Try to keep the soil consistently moist, but not soggy. Soggy soil can lead to root rot and dead seedlings. It should feel similar to a damp sponge. Use caution when watering young seedlings. You don’t want to water them by just pouring water over them. Seedlings are easy to damage if you simply pour the water over the top of them. 

Avoid damaging your seedlings by watering them with a light mist. A misting bottle is the perfect way to gently water your seedlings. You can also water seedlings from the bottom using a seed starting tray and flat that will hold water. Fill the flat with water and place your seed starting trays into the flat. The soil will absorb water from the flat but won’t absorb so much water that the plant will develop root rot. This method allows you to skip the daily misting sessions. Just perform a daily check to ensure that there is still water in the bottom of the flat.

Nutrients Needed

Seeds don’t require fertilizer to sprout, but they will need nutrients once they emerge. You can apply a topical fertilizer to the soil when you notice your seeds are germinating. Keep the fertilizer off of the plants to prevent burns. Some seed starting mixes come with fertilizer in them.  

It’s a good idea to have both a water-based, fast acting fertilizer and a slow release fertilizer. Apply both fertilizers to ensure that your seedlings are getting nutrients quickly from the fast acting fertilizer and gradually over time from the slow release fertilizer.

When choosing a fertilizer for your seedlings, look for a fertilizer that is well-balanced. It should have all three primary macronutrients: nitrogen, phosphorus and potassium. Calcium, magnesium, sulfur, and micronutrients are also helpful.

Check Seedlings Often

Get in the habit of checking on your seedlings each morning and evening. Seedlings grow rapidly and changes can occur quickly. Monitor the soil moisture. You may need to adjust your watering as your plants grow. Also check for signs of stretching. Plants that aren’t getting enough light will stretch towards light, causing elongated and weak stems. Adjust lighting if necessary.

Thinning Out

As your seedlings grow, you’ll also want to make sure that they aren’t overcrowded. Seeds should be sown with 1-2 seeds per cell or pot. This can be difficult to do with seeds that are very small, like lettuce seeds, herbs or carrots. You may find that as your seedlings grow that they need more space.

Overcrowded plants are more likely to develop disease and will compete with one another for nutrients, water, and light. You can prevent this by thinning your seeds. To thin seeds, look at the plants carefully. Find plants that are smaller or appear less vigorous. Cut these plants at the base, leaving the larger plants to grow.

Where to Keep Seedlings

Seedlings grow best in a place that has consistent light and temperatures. A warm place in your home is ideal. If you have a sunroom, this is the perfect place to start seeds and keep seedlings.

A southern facing window can also offer many hours of natural light. Don’t have a southern facing window?  Use artificial light to provide your plants with the light they need to thrive. Seedlings will grow best with 12-16 hours of light.

We don’t recommend starting seeds in a garage or barn unless it is heated. These outbuildings have significant fluctuations in temperature that your seedlings may not be able to tolerate. They are a good place to start hardening off your seedlings, but it’s not the best place to start seeds and nurture young seedlings.

Prevent Dampening Off

A common problem that gardeners face with seedlings is mold. The seedlings’ environment is the perfect place for mold to grow. Mold thrives in moist environments, like the soil mix around your seedlings. Mold can quickly get out of hand and can kill your seedlings. The white mold that can grow on the top of the soil is responsible for the #1 seed starting problem- dampening off.

Dampening off will kill your seedlings. If you notice the white mold, don’t fret. Not all hope is lost!  There are a few things that you can do to help your plants out.

Gently scrape off any noticeable mold from the surface of the soil. You can take a small fork or knife and carefully disturb the soil. Don’t disturb the soil deep enough to harm the roots. Disturbing the soil will help to dry it out faster.

Stop watering the soil until it is dry. Soil that is too wet is the main cause of the mold that leads to dampening off. Reduce the soil moisture to kill the mold.

If possible, allow your seedlings some time in natural sunlight. Increase the air circulation using a ceiling or box fan and check that the seedlings have enough space between plants for air to flow. If plants are crowded, space them out or consider thinning them.

Final Thoughts

You’re well on your way to successfully starting your garden from seed! Have any questions about starting seeds? Drop them into the comments and we’ll be sure to respond.

Shelby DeVore is the founder of the homesteading blog Farminence. She teaches people how to garden, raise livestock and be more self-sufficient. She currently lives on a farm in West Tennessee with her husband, three kids and too many animals to name.


Apr 29, 2022

Hi Roni,
If your seedlings have thin stems it is a good indication they are not getting enough light. Turning will help, but it is not going to solve the issue. Supplemental light is needed in order to help your plants grow properly. Attached is an article addressing seedling issues as well as an article from our blog that provides good guidance on helping to choose a light stand. We hope you will find this information helpful.

Harris Seeds
Apr 29, 2022

Hi Gerald,
Germination issues are common in pelleted seed when moisture levels are not properly maintained. Simply water-in these pellets and follow the recommended crop culture for the variety or mix. The water-soluble wax of these pellets takes longer to completely dissolve even when fully submerged in water. Do not attempt to dissolve the pellet within a single watering. Instead, maintain a moisture level of four to five (medium wet to saturated) from sowing until the pellet is fully dissolved. Maintain high relative humidity in the germination environment along with adequate soil moisture, exposing the seed to proper germination conditions. The use of plastic domes or regular misting is helpful in keeping the adequate moisture until the seed germinates. Once the sowing stage begins, if the pellets dry out, they become hard to dissolve. This is why we highly recommend high moisture content right from the beginning.

Harris Seeds
Apr 29, 2022

My question is, how do you plant palletized seed? I have very little success getting them to germinate. I’ve tried starting a mini arrow garden I’ve tried starting them in soil flats and I leave them exposed to the light if you could give me any information on this I would appreciate it

Gerald Batzel
Apr 29, 2022

I have some seedlings where the stems are thin. I transplanted them into 4 packs, I turn them every day, will this help?

Mar 17, 2022

Hi Kimberly, thank you for contacting us. The method you use to start your seeds is entirely up to you. The Aerogarden certainly makes it easy to have everything contained in a small space. That said, it doesn’t always work for larger crops that require more space to grow (tomatoes, peppers, squash, etc). We have many customers who use the Aerograden to grow some of their flowers, vegetables and herbs. I’m sure with a little trial and error you will have great success. Please don’t hesitate to contact us if you have any specific questions.

Harris Seeds
Mar 11, 2022

Hi Robert, thank you for contacting us. A good method for determining when you need to transfer your tomatoes to a larger container is by monitoring root development. When you see roots starting to push through the bottom of your 1"cell it’s time to transfer your tomatoes. When your tomatoes are ready to be transferred, grasp the stem near the base, close to the soil and gently pull up. The seedling should pull cleanly from the cell with its root ball in tact. I hope this information helps. Let us know if you have any other questions.

Harris Seeds
Mar 17, 2022

I like to start my seeds using the Aerogarden, Is this a bad process to use …is soil better?

Mar 11, 2022

When my tomato seedlings have developed true leaves is it time to transfer from a 1 inch cell to larger containers?
Thanks, Robert

Robert Sloop
Jan 31, 2022

Also what kind of lights should I use?

Helen Eggleston
Sep 29, 2021

I plant in my backyard in the Caribbean( Jamaica) What’s the best way to grow Brussels sprout? I haven’t seen anyone grow this crop in Jamaica😊

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