What To Do After Germinating Weed Seeds

Growing seedlings indoors isn't hard. Learn all you need to know about water, light, soil, fertilizer, and more in this detailed care guide. Seed Starting, Part 2: What To Do After Germination Check out our latest tutorial video below about what to do with your seeds after they have started to germinate (when they’ve started to grow). Care for seedlings once sprouted amounts to more than just giving them water. Healthy, robust plants produce faster with higher yields, which is a winning situation for the gardener. A few tips on how to take care of seedlings can be found here.

How To Take Care Of Seedlings & What To Do After They Sprout

Growing seedlings is fun, but keeping them alive can be challenging. In this detailed seedling care guide, I will show you everything you need to know about how to grow healthy starts for your garden.

Getting your seeds to germinate is one thing, but figuring out what to do with seedlings once they start to grow? Well, that’s a whole different ballgame.

But, once you learn all about proper seedling care, you can easily keep them thriving. Plus you’ll feel confident that they’ll be strong enough to survive the transition to the garden.

In this guide, I will teach you everything you need to know about growing seedlings. If you want to start from the beginning, then get my best tips for how to grow seeds indoors here.

Table of Contents

Growing Seedlings Indoors

I love growing my own seeds! No matter how many times I do it, I always get super excited when I see the first signs of life in my trays. It’s so much fun!

But after the elation of seeing your first sprouts popping out of the dirt wears off, reality sets in and you might suddenly wonder… Oh crap, my seedlings are growing! NOW what do I do. (gulp)

Don’t panic, I’ve got you covered. Keep reading and I’ll show you exactly what to do with seedlings after they start to germinate.

New seedlings shortly after germination

Seedling Care Instructions

Growing seedlings doesn’t have to be a huge struggle! With the proper care, they will not only survive but they will thrive in your garden.

Follow these instructions for taking care of seedlings after germination…

Light For Seedlings

Light is one of the most important factors of seedling care, and that’s why I’ve listed it first. Some will grow OK sitting next to a sunny window, but most will require more light than that.

You can learn more about proper lighting for seedlings here, but I’ve listed some quick tips for you below.

  • When to start using lights – You should turn the grow lights on as soon as you see the first specks of green popping out of the dirt.
  • Types of lights – There are tons of options here. You can buy a full-blown system, or just get the grow lights.
  • Amount of light – Ideally, the grow lights should hang 3-4 inches above the seedlings at all times, and be kept on for 12-14 hours a day (an inexpensive outlet timer really comes in handy for this!).

Seedlings leaning over

Proper Seedling Watering

Proper watering is another extremely important part of successful seedling care. Seedlings need consistently moist soil. They can’t survive long without water, and should never be allowed to dry out completely.

However, never allow the soil to be wet all the time either. Soggy soil promotes pest infestations, mold growth in trays, and diseases that can kill your seedlings, like damping off.

Plus, too much water will ultimately kill them, and you don’t want that. Here are some tips to get it right…

  • How often to water – You should check on your seedling trays a few times a day to see how moist the soil is. Once the top layer of soil starts to dry out, then it’s time to water. They will need to be watered more often as they grow larger.
  • How to water – The best way to water is by pouring it into the tray, and then allowing the soil to absorb it through the drainage holes. Bottom watering will help ensure the roots get plenty of moisture, and avoid disturbing or displacing the delicate seedlings. Be sure to dump out any that’s not absorbed after 30 minutes.
  • How much to water – Fill the tray just enough to cover the holes in the bottom of the cells so they can absorb it.

An inexpensive soil moisture gauge is a wonderful tool that will help you give your seedlings the perfect amount of water. I highly recommend getting one.

Watering seedlings from the bottom, not the top

Seedling Ventilation & Airflow

A common question I get from newbies is when to remove the humidity dome for seedlings. Great question!

It’s time to remove the dome lid once most of the seedlings in the tray have started to grow. But it’s best to do this slowly by ventilating the lid, rather than just removing it.

Start by propping it open an inch. Then keep propping it another inch or so every few days until the lid is completely off. Once the humidity dome is off, you can leave it off.

Airflow is also important for growing seedlings and preventing some common problems (like mold and overwatering).

Once the lid is off, I like to use an oscillating fan to provide additional ventilation, and help to strengthen them.

I keep my fan plugged into the same outlet timer as my grow lights. I set it on low so it rotates and gently blows over the seedlings all day long, then it automatically turns off at night.

Keep in mind that the soil can dry out very quickly after you remove the lid, especially if you use a fan, so you should check the moisture level more often.

Preparing to remove humidity dome for seedling ventilation

Thinning Overcrowded Seedlings

If there’s more than one seedling growing per cell, then you will need to thin them. It is really hard for some people to do this, but it’s very important.

Below are a few tips to get you started, but you can learn how to thin seedlings step-by-step here.

  • Why do seedlings need to be thinned? – Because otherwise they will start to compete with each other for light, water and nutrients. It’s also really difficult to give seedlings proper airflow when they’re overcrowded.
  • How big should seedlings be before thinning? – You can start once your seedlings have a few sets of their true leaves. Snip out the weakest so that only the strongest one is left growing in each cell.
  • How to pick the strongest seedling – Keep the one that looks the healthiest and is the most compact, and pinch or snip out the leggy or weak looking seedlings. If they all look the same, then just choose one of them to keep per cell.

Using an oscillating fan to grow strong seedlings

Fertilizing Your Seedlings

Once you start to see true leaves, it’s time to begin fertilizing them as part of a regular seedling care routine. But you don’t want to feed them a full dose of fertilizer, because they are just babies. Follow these tips…

  • How to fertilize seedlings – Start feeding them with a weak dose of liquid fertilizer at first (about 1/4 of the regular dose). Then slowly increase the strength of the dose as they grow larger.
  • The best fertilizer for seedlings – I recommend using natural, organic fertilizers rather than synthetic chemicals. Chemicals are notorious for burning seedlings, and they don’t work as well as organic types do.
See also  Lawn Weeds With Seed Pods

I use (and highly recommend) an organic compost solution (you could also buy tea bags to brew your own) on all of my indoor seedlings.

Liquid kelp and fish emulsion are also wonderful, and seedlings absolutely love them… but beware that these can get a bit stinky when used indoors.

A few of the best fertilizers for seedlings

Transitioning Mature Seedlings

Once your seedlings grow larger, it’s time to start thinking about transitioning them to the next phase. Most will do best when they’re put into larger pots, rather than left growing in the small starter cells.

That will give them plenty of room to grow larger before it’s time to move them outside and into the garden.

When To Move Seedlings To Pots

The general rule is that, once the seedlings have grown to be about twice as tall as the height of the tray, then they should be put into bigger pots. Learn all about repotting seedlings here.

Most can handle staying in the small containers for a few weeks, as long as you keep them watered.

But, if it’s going to be more than a week or two before you’re able to plant them into the garden, you should pot them up.

Plantable pots are a great option, and they make planting seedlings into the ground later on super easy.

Peat pots are popular and fairly inexpensive, I recommend buying either the 3″ size peat pots or 4″ peat pots for seedlings.

If you’re worried about the sustainability of peat, then get some that are made out of coco coir. You can use a 2.25″ size, or a 3″ size pot for seedlings. Heck, you can even buy pots made out of cow manure! Wow!

Of course you can always put them into reusable plastic pots if you have them on hand, to save yourself some cash.

Moving seedlings to larger pots

Preparing Seedlings For Planting Outside

Hardening off is a crucial seedling care step that many newbies miss. But, if you planted your seedlings from your house directly into the garden, they would probably wither and die (eek!).

Seedlings growing indoors need time to get used to being outside before they are planted into the garden. So never skip this step!

Once the weather warms in the spring (above 50 degrees F), put your seedlings outside in a shady location for several hours each day. They should be protected from sun, wind and heavy rain.

Gradually expose them to the sun over several days. Keep in mind that the soil will dry out much faster outside, and the seedlings may need to be watered more than once a day, so check on them regularly.

When the weather is warm enough, they can be left outside overnight. Learn exactly how to harden off seedlings step-by-step here.

Hardening seedlings before planting them into the garden

When To Plant Seedlings Into Your Garden

Ok, so you’ve got these seedling care steps figured out, and you’ve managed to keep your babies alive. That’s awesome! Now you’re probably wondering when you should put them into the ground.

Cold weather plants like broccoli, cauliflower, carrots, radish, parsley, leafy greens (like lettuce) and others that can handle light frost can be planted as early as 2-4 weeks before your average last frost date.

Warm weather seedlings like tomatoes, cucumbers, basil, beans, squash and peppers shouldn’t be planted into the garden until after all chance of frost is gone.

If you don’t know your average last frost date, check with a local garden center. Get more details about how to figure out when to transplant seedlings into the garden here.

Troubleshooting Common Seedling Care Problems

Once you get the hang of it, you’ll find that it isn’t all that hard to grow seedlings. But it can be extremely frustrating when they start having problems, and you don’t know why.

So to help you figure it out, here are a few of the most common seedling care issues, and their causes…

Leggy Seedlings

This is the biggest problem with growing seedlings indoors, and it happens when they don’t get enough light.

Add a grow light, and hang it right over the top of the seedlings. Then leave it turned on for 12-14 hours a day.

Seedlings Leaning Over, Stretching, Or Growing Sideways

Inadequate light is the main cause, but it can also happen if the lights aren’t positioned properly.

If you’re trying to grow seedlings in a window, then add a plant light. If you already have a light, then move it so that it is directly above the seedlings at all times.

Seedlings Dying After Sprouting

If your seedlings died shortly after they started growing, then it was likely because of seedling blight.

This is a disease that causes something called “damping off”, which kills seedlings at the base. The only way to prevent this is to disinfect your seed trays before using them again.

Yellow Seedlings

The main cause is overwatering. Be sure that the soil is never soggy, and allow the very top to dry out a bit between waterings.

Small Seedlings, Or They’re Not Growing

Seedling growth can be stunted when it’s too cold in the room, if they are over or under watered, or if they aren’t getting enough fertilizer.

Healthy seedlings growing indoors

Seedling Care FAQs

In this section, I will answer the most commonly asked questions about growing seedlings. If after reading this guide and these FAQs you still can’t find the answer to your question, then ask it in the comments below.

What are true leaves?

The term “true leaves” refers to any of the ones that grow after the first two leaves. They look like tiny versions of the leaves on a mature plant.

How long does it take for seedlings to grow true leaves?

That depends on the type of seedling. Some will start growing true leaves within a few days of germination, others can take several weeks.

It’s best to check the seed packet, or research the type of seedling you’re growing for specific timing.

How do you make your seedlings grow faster?

Heat, light, and fertilizer are three ways to improve seedling vigor, and make them grow faster.

If yours aren’t growing, then check the temperature of the room first. If it’s below 65 degrees F, then try keeping seedlings warm using a space heater or a heat mat.

Also be sure you’re providing adequate light and fertilizer to help speed up the growth. See the”Light For Seedlings” and “Fertilizing Your Seedlings” sections above for more details.

When should I water my seedlings?

Water your seedlings when the tray is empty, and the top of the soil is starting to dry out. Never allow the soil to dry completely though. Read the “Proper Seedling Watering” above for more details.

How do you grow strong seedlings?

All of the factors in this guide are important for growing strong seedlings. But adequate lighting and proper watering are by far the most important to help them thrive.

Can seedlings get too much light?

Yes. If you leave the lights on 24 hours a day, it can confuse them, and cause problems later on when you move them outside.

It’s best to simulate the natural sunlight pattern, and allow them a period of darkness each day.

How many hours of light do seedlings need?

Giving your seedlings 12-14 hours of light a day is ideal, and using an outlet timer makes it a snap.

When should I start seedlings?

It depends on the type of seeds. Follow the instructions on the seed packet to determine when to plant them. You can learn all about when to start seeds indoors here.

See also  Loud Dream Weed Seeds

Where Can I Buy Seedlings?

You can find seedlings for sale at your local garden center in the spring and summer. Be sure to shop early for the best selection though, cause they can sell out fast.

Learning what to do after they start growing, and keeping them alive and healthy is tricky. But if you follow the seedling care tips above, it will be a snap! Not only will they survive the transition into the garden, but they will also thrive all summer long!

Looking for more more help growing any type of seed you want? Then you should take my online Seed Starting Course. It’s a fun, comprehensive, and self-paced online course that will show you exactly how to easily grow strong, healthy seedlings for your garden. Enroll and get started now!

Otherwise, if you just need some tips for growing seeds inside, then my Starting Seeds Indoors eBook would be perfect for you! It’s a quick-start guide to planting seeds indoors for beginners.

Leave a comment below and share your seedling care and growing tips.

About Amy Andrychowicz

I live and garden in Minneapolis, MN (zone 4b). My green thumb comes from my parents, and I’ve been gardening most of my life. I’m a passionate gardener who loves growing everything from vegetables, herbs, and flowers to succulents, tropicals, and houseplants – you name, I’ve grown it! Read More.


Mary Anne Watt says

My seedlings are under grow lights right now. My Snap dragons have lost their tops! A few of mystocks have little nibbles on the edges of the leaves.
What could be doing this?
Thank you in advance for your help.

Amy Andrychowicz says

How weird! It sounds to me like you somehow have a critter hiding in your flats, and it’s eating your seedlings. My guess is either some kind of tiny caterpillar, but it could be a baby slug (if it were full-sized, your seedlings would have been gone in one day, LOL!). Inspect the leaves very closely to see if you can find the culprit. They are teeny tiny when they’re babies, and can be very hard to see. Slugs only come out at night, so wait until after dark and check for them with a flashlight. Good luck!

Hello I am trying to grow Asian greens but they seem to be always leggy seedlings. I start indoors as it’s quite hot here in swq . I put them in sun in mornings and then after true leaves come plant out side under shade cloth . If I am doing something wrong your advise would be greatly appreciated.

Amy Andrychowicz says

It’s difficult to care for bean seedings indoors because they need a lot of light, and they grow very fast. A sunny window won’t be enough to keep them from getting leggy. So, for bet results, you’ll either need to add a grow light indoors and leave them on for 12-14 hours/day, plant the seeds outside in a pot or other container, or direct sow them in your garden.

Deb schaefer says

Hi! I am a gardener from forever but this year decided to go that step further and start my own plants. What an adventure! My guy is also an avid hippie gardener and we love to do things our own way in the gardens. No rules just joy! All of your information is just exactly what I was looking for. One question though, I have heard that topping the tomatoes and peppers will make for a sturdier and fuller plant. True or not true, and how is this done if it is true?? Thank you for your great advice! Happy playing in the dirt and the sunshine

Amy Andrychowicz says

Wonderful to hear, you are welcome! It’s certainly not necessary to cut the tops off of your pepper or tomatoes seedlings. I’ve never done that before, and mine all do great in the garden.

Sherri Becker says

Hi – Thank you for all the information you provide! I’m also from MN and this year is my first adventure of starting seedlings. Based on your writings, I transplanted a few of my plants that had grown to be too tall for the dome into larger pots. I’m concerned about them. It’s only been a day but how do I know when I need to start using the fan? Is that something to do right away on those that have been potted up? I got the timers and have the lights and fan on a timer but really worried about it being too soon for the air. Any help is appreciated! Thank you

Amy Andrychowicz says

You’re welcome! Great job on growing your seedlings so far, sounds like you’re doing everything right. I start using the fan as soon as I take the lids off my flats. So, you can turn yours on anytime now. Just keep in mind that the soil will dry out a little faster with the fan blowing on your seedlings. So check on them a few times a day to make sure it’s not drying too fast. Good luck!

Seed Starting, Part 2: What To Do After Germination

Check out our latest tutorial video below about what to do with your seeds after they have started to germinate (when they’ve started to grow). Then keep scrolling for some tips and links to help you out! If you missed the first video on How to Successfully Start Seeds, be sure to check that out first, as it will get you started on growing a great garden – whatever your skill level.

>> Download: When to Start Seeds Indoors

We also have for you an easy-to-follow written guide on when to start what.

1. Light

Your seedlings will need light, but they also need periods of rest (darkness) too. A good rule of thumb is to turn the grow lamps off when you go to sleep, and turn them on when you wake up (or use a timer). Read all about different types of grow lights here.

Seedlings need blue night and red light. Sunlight includes both. Red light stimulates the growth of leaves and flowers. Blue light regulates the growth/size of plants.

Don’t use incandescent light, use fluorescent. Full spectrum bulbs include both red and the blue light, or you could use one warm (red) light and one cool (blue) light.

The grow lamp should be about 2-4 inches above the seedlings, so adjustable lights are helpful. You can find the Tabletop Garden Starter® Grow Light Kit shown in the video (and in the photo above) from Gardener’s Supply.

Be sure you clean the lightbulbs, as dust and dirt can cut down on the amount of light emitted.

Hold your hand above the seedlings. If it feels warm, the light is too close.

2. Water

Water from below, not above, to ensure that you don’t squash the seedlings. Make sure your seedlings aren’t sitting in water, or you’ll have issues with rotting, fungus, and soil gnats.

Your seedlings might need to be watered if:

  • The soil looks lighter
  • The soil pulls away from the edge of the cell

Self-watering seed starting kits use capillary mats, but be sure to check the water levels on those as well.

3. Food

Seedlings need food when they get their “true leaves.” The first leaves that come up are typically embryonic leaves from the cotyledon (part of the seed) so look for the second (“true”) leaves to appear before you start fertilizing. Use fertilizer at a weaker strength than you would for full-sized plants.

There are several different options for how to fertilize your seedlings. The ones shown in the video are Sustane Compost Tea Bags and Alaska Fish Fertilizer 5-1-1 Concentrate 1 Quart

See also  Free Weed Seed Catalogs

4. Airflow

Your seedlings will be healthier and more sturdy if air is flowing above and around them. A fan can be used – we recommend putting it on a timer, just like your grow lights.

5. Room to Grow

Most people put more seeds than are needed in each cell, so you’ll need to either (carefully) pull out the weaker ones from each cell, leaving one healthy one, or cut them off at the base. Monica demonstrates both methods in the video.

Be sure to check your seed packet to see how long it should take your seeds to germinate. If no seedling has appeared by a few days later than expected, sow some new seeds.

6. A Bigger Pot (optional)

It’s not needed, but if you’re not moving your seedlings into a garden for several weeks, you might want to transfer them to a larger container. If your plant is about two times the size of the container it’s in, or you can start to see roots below the cell, you might want to move it to give it more room to develop, access to more nutrients and more moisture, and the roots will have more space to grow. A 3 to 4″ pot should work well.

If you’re reusing pots, be sure you wash them well before you use them.

You can also use Eco-friendly Seed-starter Cowpots, which you eventually plant into the ground, adding nutrients and organic matter to the soil.

Use a potting mix (such as the Organic Potting Mix, 20 Qts. from Gardener’s Supply) when you transplant your seedlings. Make sure that it is adequately moist – if you grab a handful and squeeze it, it should hold together, but if you move your hand, it should fall apart (see the video at about the 23 minute mark for a demonstration of this).

When transplanting, never grab a seedling by the stem, or you could damage or kill the plant. It’s better to try to push it up from the bottom of the cell, and try to take it out in one piece.

After transplanting, be sure to still water your seedling from below.

Important note: when you do move your seedlings outside, you need to do something called “hardening off,” which is slowly exposing them to the conditions they will encounter in your garden.

7. Label

Be sure to label your seedlings so you know what they are!

Ones shown in the video include ones similar to these seed markers. The garden stakes from Botanical Interests are currently sold out. One of our YouTube viewers also suggested using venetian blinds as labels. We thought that was a great idea!

What are you growing from seed this spring? Let us know in the comments below! And don’t forget to subscribe to our YouTube Channel.

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Please note that the Amazon and Gardener’s Supply links (and only the Amazon and Gardener’s Supply links) above are affiliate links. Should you choose to purchase products through these links, GPReview will make a small commission (at no extra cost to you) that helps to support this website and our gardening product reviews. Thank you!

About The Author

Sarah, originally from Wisconsin, prefers to be outdoors whenever possible. She has been known to high-five trees on hikes, tests the limits of her balance on kayaks, and is re-discovering a love of cycling. She works behind-the-scenes at the Gardening Products Review, located in sunny Tucson, Arizona.

Seedling Care Tips: Caring For Seedlings After Germination

It’s that time of year when self-starting gardeners have sown their seeds indoors and are contemplating the next steps. Those tiny little sprouts have shown up and need the best care before their planting out into the world. Care for seedlings once sprouted amounts to more than just giving them water. Healthy, robust plants produce faster with higher yields, which is a winning situation for the gardener. A few tips on how to take care of seedlings should help ensure you bumper crops your neighbors will envy.

Things That Can Kill Your Seedlings

Growing plants from seeds is a rewarding endeavor that reaps big rewards. Caring for seedlings after germination isn’t hard, but attention to such things as damping off, nutrition, temperature, water, light and transplanting will guarantee stout seedlings that survive the rigors of outdoor living. Even the most experienced gardener can benefit from some seedling care tips to boost their success.

Those little green shoots poking through the soil send our hearts soaring with thoughts of fresh produce and the joy it brings to our summer entertaining. Damping off is a real threat when caring for seedlings after germination. Just because the seeds managed to sprout doesn’t mean the plants are out of danger.

Damping off is a fungal disease that causes the tiny plants to wither and die. It can stem from contaminated containers or soil and is worsened by incorrect watering practices. Use a sterilized soil or soilless mix and wash containers carefully to prevent contaminating the seeds and plants.

Keep plants in a sunny location during the day but move them at night to prevent cold drafts from stunting their growth. Too much water can cause tiny roots to rot while too little will see your new babies shrinking and even dying.

How to Take Care of Seedlings

One of the basic seedling care tips is that you don’t need supplemental food until the cotyledon has completely emerged and several sets of true leaves are present. Feeding your new kids too early can burn roots and tender foliage. Seed starter mixes are formulated with all the nutrients your new plants should need until they are planted outside. A soilless-grown crop will benefit from fertilizer diluted by one-quarter once per week.

Water your plants when the surface of the soil is dry to the touch. The exact time will depend on how warm the room is and how hot the light. The best temperature for optimum growth is between 70 and 80 F. (21 to 26 C.). Avoid exposing seedlings to temperatures below for more than a few hours and above 100 F. (37 C.), which will stunt root growth.

Thin the plants where multiple seeds have sprouted in the same cell or container.

Transplanting and Hardening Off

Successful care for seedlings once sprouted will take you on the road to transplanting. Plants grown in peat cells should receive a new pot that will allow for future growth. You’ll know when it is time if you can see roots out of the bottom of the cell. Spoon out the seedlings to avoid damaging the stem by lifting them. Use a good sterile soil again and water them well immediately. You can use any container, but peat pots and other compostable materials allow for easy insertion into the garden bed without damaging roots. As an added bonus, the container will break down and add nutrients to the soil.

Hardening off is a step that shouldn’t be skipped. This is done before your plants are introduced to the garden bed. Two weeks before planting them outside, gradually introduce your babies to the conditions. Move them outside for longer and longer periods to acclimate them to the wind, light levels, temperature and generally get them used to the idea that they will be outdoor plants soon. This will prevent the stress that is associated with seedling failure after outdoor transplanting. After a couple weeks, plant the seedlings in a prepared seed bed and watch them grow.