Growing your plants from seed takes time, but it’s a great way to start your garden earlier in the season and get the most bang for your buck in terms of plants. If you’re wondering how to germinate seeds, you’ll need some simple equipment and the right light, but it’s not a hard process from start to finish.
Because each seed comes with unique seed-starting requirements, it’s best to start small by growing a few varieties at first and expanding as you get a feel for how to germinate seeds. Some seeds, like marigolds or tomatoes, are very easy to start inside. A few other good choices for novices include zinnia, basil, nasturtium, coleu, and cosmos. If you’re a beginner and just learning how to germinate seeds, pick those first, and then move on to more challenging options. Below, we’ll outline a few ways how to germinate seeds, tips, and care instructions.
Germinating your seeds quickly can help you get a jumpstart on the growing season when you plant them in the spring.
Defining Seed Germination
Seed germination is the process of growing plants from seeds instead of going out and buying seedlings or ready-grown plants from nurseries. Sprouting your seeds indoors is an effective way to boost your germination rate instead of germinating them outside right in the siol. Also, starting your seeds indoors is a common method with people who have vegetable gardens in their backyards, especially people who live in northern, colder climates where young seedlings can struggle to survive under colder conditions.
What Types of Seeds Will Germinate Indoors
Before you learn how to germinate seeds, you should know which seeds will germinate indoors. The good news is, you can germinate most seeds indoors if you follow the unique seed starting guidelines. The benefit of germinating your seeds indoors, especially if you’re in a colder climate, is that you lengthen your growing season. This gives slower-growing plants like tomatoes, watermelon, pumpkins, and sweet melons time to mature before the first frost of the season in the autumn months comes along.
It’s also possible to germinate quick-growing vegetables inside. Start the seeds for your chosen vegetables like radishes, Swiss chard, or lettuce roughly four to six weeks before the last frost of the spring in your area to give them a jumpstart on the growing season.
Average Seed Germination Periods
Your vegetable seed germination rates will vary, depending on the air and soil temperature in your climate. Keeping the seeds at an ideal temperature will speed up germination while colder weather slows the germination rates. For most seeds, the germination time wil be the fastest when the temperatures hover around 70-degrees F. At the optimal temperatures, the following seeds take roughly this long to germinate:
- Asparagus – 14 to 18 days
- Beans – 4 to 10 days
- Beets – 4 to 10 days
- Broccoli – 7 to 10 days
- Brussels Sprouts – 3 to 10 days
- Cabbage – 5 to 10 days
- Carrots – 6 days
- Cauliflower – 4 to 10 days
- Celery – 10 days
- Chinese Cabbage – 4 to 10 days
- Collard Greens – 5 to 10 days
- Corn – 4 to 10 days
- Cucumber – 5 to 7 days
- Eggplant – 10 to 15 days
- Garlic – 7 to 14 days
- Kale – 5 to 7 days
- Kohlrabi – 5 to 10 days
- Lettuce – 2 to 10 days
- Mustard Greens – 4 to 6 days
- Okra – 7 to 12 days
- Parsley – 5 to 6 weeks
- Parsnips – 5 to 28 days
- Peas – 5 to 7 days
- Pepper – 7 to 10 days
- Pumpkins – 4 to 10 days
- Radishes – 4 to 10 days
- Spinach – 6 to 14 days
- Squash – 7 to 10 days
- Swiss Chard – 7 days
- Tomatoes – 5 to 7 days
- Watermelons – 4 to 10 days
Picking out vegetables with quick germination times will allow you to maximize your yield when it comes time to harvest them.
Benefits of Pre-Sprouting Seeds
Normally, when you sow seeds in a growing medium, like peat pots or in a damp seed starting soil. You then plant the seed, cover it with soil, water it, put it in a warm location, and wait for your seeds to sprout and break through the surface of the soil. If you use the paper towel method when you’re learning how to germinate seeds, you germinate the seeds first and put the sprouted seeds with the root into your seedling container to grow. You can see the seed and don’t have to wonder how it’s doing out of sight under the soil. A few advantages of pre-sprouting your seeds include but are not limited to:
- Conserves Space – You won’t have to sow an entire tray of seeds and hope that half of them germinate. Insead, you sprout your seeds in a container and only plant the ones that germinate. You don’t even need to use a seedling heat mat.
- Eliminates Thinning Out Seedlings – When you pre-sprout your plants, you won’t need to get rid of three or four seeds into the pot and hope one germinates only to have all of the seeds sprout and force you to thin your plants.
- Excludes Bad Seeds – You will only plant the seeds that successfully germinate. The ones that don’t, you can simply throw away.
- Saves Money – Instead of getting rid of your older seed packets, you can germinate seeds using the paper towel method to see if they’re still viable or if it’s time to get rid of them.
- Saves Time – Pre-sprouting your seeds saves time that you’d normally spend waiting on them to sprout. It helps to speed up the germination process because you can set up the ideal air, moisture, and temperature conditions for the seeds to thrive and germinate.
How to Germinate Seeds in Seven Steps
Every plant’s seeds are inactive or dormant until the conditions are right for them to germinate. This is one of the most important aspects of learning how to germinate seeds. A seed will start germinating once it gets exposed to moisture and warmth. First, the seed will absorb oxygen and moisture, and this triggers the embryo in the seed to wake up.
Next, it starts to swell and break down the seed coat. As it does so, it absorbs bigger amounts of oxygen and water before sprouting the roots, and this is followed by a shoot that forms the plant’s stem and foliage as it grows. The following will walk you through how to germinate seeds in seven steps.
Step One – Get the Timing Right
The goal with starting your seeds indoors is to have them ready to go outside as soon as the weather is favorable. Start by taking a look at the seed packet, and this should tell you exactly when to start your seeds inside. Usually, it’ll say something along the lines of, “Plant inside six to eight weeks before the last frost date.”
Some vegetable types, like squash and beans, are best when you start them outside. There is very little benefit to growing them inside because they grow and germinate very quickly. Some flowers, like poppies, work better when planted outside. These seeds usually have “Direct Sow” written on the seed packet.
Step Two – Find the Right Containers
You can start your seeds in virtually any container type as long as it’s between two and three-inches deep and comes with drainage holes. If you’re someone who likes to DIY things, you may want to grow your seedlings in milk cartons, yogurt cups, or paper cups. Many people prefer to use trays as they’re more convenient, especially when it comes to learning how to germinate seeds. It’s easy to fill the trays, and they come with a watering system that ensures each seed gets consistent moisture. They’re also easy to pick up any move as needed.
Step Three – Prepare the Potting Soil
Pick out a potting soil that is made for growing seedlings. You don’t want to use the soil from your garden or re-use potting soil you’ve used in your houseplants. Start with a sterile, fresh mix that helps to ensure you get disease-free, healthy seedlings. Before you fill up your containers, use a tub or bucket to slowly moisten your potting mix. The goal is to get the soil moist, but you don’t want to get it sopping wet, gloppy, or crumbly. Fill your containers and pack the soil firmly in the soil to eliminate any gaps.
Remember that most soil mixes have few, if any nutrients in them. So, you’ll want to add a liquid fertilizer a few weeks after your seeds germinate. You should keep doing this every other week or so until you transplant your seedlings into the garden.
It’s essential that you use the correct potting soil when you have seedlings so they don’t have issues with mold or fungal infections.
Step Four – Start Planting
Check your seed packets to see how deep you want to plant your seeds. Some of the smaller seeds get sprinkled right on top of the soil’s surface while larger seeds will need to be buried under a layer of soil. You want to plant two seeds per cell. If both seeds happen to germinate, you can snip one off and allow the other to grow. It’s helpful to make a few divots in each pot to accommodate your seeds. After you put a seed in each divot, you can go back and cover them.
Slowly moisten your newly planted seeds with a small watering can or mister. To speed up the germination process, cover your pots with a plastic dome or plastic wrap that fits over your seed-starting tray. Doing so will help keep the seeds moist before they germinate. When you see the green stems pushing through the soil, remove the cover.
Step Five – Water, Feed, and Repeat
As your seedlings start to grow, use a small watering can or mister to keep the soil moist but not soaked. Allow the soil to dry slightly between watering sessions. Set up a small fan to ensure there is great air circulation around the plant to help prevent diseases. You also want to remember to feed your seedlings regularly using a liquid fertilizer that you mix at the rate recommended on the package.
Step Six – Light
Seedlings require a lot of light. If you’re growing them in a window, pick out a south-facing window for exposure. Rotate your pots regularly to keep the plants from reaching and leaning into the light. If the seedlings don’t get enough light, they’ll be weak and leggy. If you’re growing your seedlings under grow lights, you want to adjust them so they’re a few inches on top of the seedlings. Set your lights on a timer for 15 hours a day. Keep in mind that your seedlings also require darkness so they can rest. As the seedlings grow taller, you’ll raise your grow lights.
Step Seven – Move Your Seedlings Outdoors Gradually
It’s never a good idea to take your seedlings from inside straight outside from a protected environment into the garden. At this point, you’ve been coddling these seedlings for weeks, so they need a gradual transition process outdoors. This is a process known as hardening off. Around a week before you plan to move the seedlings into the garden, put them in a protected spot outside that is out of the wind and partially shaded for a few hours. At night, you’ll bring them back inside. Gradually, over 7 to 10 days, you’ll expose your plants to more sunshine and wind. A cold frame is a fantastic way to harden off your seedlings.
How to Germinate Seeds on a Paper Towel
The first way how to germinate seeds many people learn is how to use paper towels to do so. It might seem like you’re taking unnecessary steps, but germinating them using paper towels can make the seeds sprout three times quicker. To do this, you’ll need to:
- Place a folded paper towel at the bottom of a plastic container or glass.
- Gradually add more water, a little at a time, until the paper towel is evenly moist. There shouldn’t be any puddles of water.
- Put the seeds on the paper towel and close the container’s lid.
- Write on the lid or on a piece of paper you tape to the lid which seeds you’re learning how to germinate inside. This is especially helpful if you’re growing seeds that look the same.
- Keep the containers out of the direct sunlight because any trapped heat can fry the seeds. Check your seeds at least once a day. Depending on the types of seeds you’re working with, some may only take a day or two to sprout. The fastest seeds to germinate include broccoli, bok choy, cauliflower, cabbage, lettuce, kale, and radishes.
The most important factor with this method on how to germinate seeds is to have the containers ready for them when they sprout. When tiny roots start to appear, plant them in the soil immediately. Long roots will make it harder to separate the seeds from the paper towels. Always plant your seeds at a depth of one to two seed sizes. So, the bigger your seed is, the deeper they’ll go in the soil.
Average Seed Germination Time
Planting your seeds in a paper towel and plastic bag will help create a mini greenhouse effect that leads to heat and moisture retention. Humidity and moisture combined creates the best environment to germinate seeds.
How to Germinate Seeds Faster – Three Tips
Even though starting the seeds indoors is already giving a jumpstart to the plant. However, there are things you can do to germinate seeds even quicker, and they include but are not limited to:
1. Pre-Soak the Seeds
Arguably one of the best kept gardening secrets is to soak your seeds to encourage quicker germination. But, why does soaking the seeds help them germinate faster? Soaking seeds works to expose the embryo to moisture, and this helps it break through the seed shell and grow quicker. Water exposure allows your seeds to swell as the water penetrates the seed coating, and the embryo will start to plump up.
However, you never want to soak your seeds for over 24 hours or it can cause them to rot. After they soak for less than 24 hours, you want to plant them straight away into the soil, either in the ground or in a container. This method will work well with all seeds, but it usually works best with bigger seeds like squash or beans.
2. Try Nicking Your Seeds
Using stratification when you’re learning how to germinate seeds can help jumpstart the process. This is the process of nicking the seed’s coat using sandpaper or a knife. Doing this will allow moisture to reach the seed’s embryo, and this causes quick germination. Scarify your seeds before you plant them, but you don’t want to leave the scarred seds out where bacteria can get in.
3. Use the Cold Treatment
Using cold to germinate your seeds quickly is to trick the seeds into thinking that they’re going through the winter period. Stratification mimics the natural cycle of the seasons as the seeds go through a cold period throughout the winter months and sprout in the spring. When you sow the seeds in the spring, you should soak them for just shy of 24 hours and put them in a sandwich back that you fill halfway with moist seed starting soil. Keep the bag in your refrigerator to mimic winter conditions.
When the seeds start to sprout and form roots, you can transfer them into pots and expose them to warmth and light. Some seeds that require cold treatment can be planted outside during the fall or stored in the refrigerator in fall and winter. Then, when spring comes around, you put your seeds in pots. To plant them outside, put the seeds in a pot, but put a thin gravel layer over the pot to prevent the soil from washing away.
Germinating your seeds as fast as you can ensures that you’ll have many more seedlings to plant come spring, and this can give you more vegetables in the fall.
Planting Pre-Germinated Seeds
Some seeds sprout much faster than others. As soon as the seed develops tiny roots, it’s ready for you to plant. Carefully transfer your seeds into your seedling containers using tweezers or a toothpick. Put the sprouted seeds on top of your growing medium, cover the seedlings with a dry potting soil mix, mist lightly with a spray bottle, and put them under your growing lights.
Be very careful not to damage your seedling’s roots. If you do, the sprout won’t survive. If the root has grown into the paper towel, snip around it and plant it with the piece of paper towel. Also, don’t pull off the seed coat before you transplant it as it’ll come off by itself with the first leaves.
How to Germinate Seeds – Troubleshooting
Even though learning how to germinate seeds sounds like a very straightforward process, you may run into trouble. Knowing how to troubleshoot issues when you run into them will increase the chances of your seedlings surviving and thriving.
1. Only one-quarter of your seeds germinated. What’s wrong?
There are several factors that affect how many seeds germinate. Check the seed packet to figure out if all of the light and temperature requirements were met. If the soil was excessively wet and cold, the seeds could have rotted. Dig up one of the seeds and take a look at it. If it’s soft and swollen, the seed has rotted and you’ll need to start over. If the soil was too dry, the seeds may have dried up and not germinated before the roots could take hold. If you used old seeds, they could no longer be viable.
2. Your seedlings look spindly. What can you do?
Plants that grow leggy and tall usually don’t get enough light. Use grow lights to help ensure that they get 15 hours of bright light each day. Warm temperatures can also encourage leggy plant growth. Try lowering the room temperature and reducing how much fertilizer you apply.
3. Your seedlings were growing, but they toppled over at the base. Why?
When the stems of your younger seedlings get withered and slowly topple over, a soil-borne fungus called “damping off” is usually behind it. The fungus is very difficult to get out of the soil once it’s present, but you can avoid it by starting the germination process with a soilless, sterile growing medium. Providing good air circulation will go a long way too.
4. There is mold on the top of the soil surface, but it’s not hurting the plant. Should you be worried?
Mold is usually an indication that your growing medium is far too wet. As long as you do something, it won’t hurt your plants. You should withhold water for a few days and try to boost the air circulation around the containers with a small fan. You can scrape some of the mold off and put the seedlings into fresh soil too.
How to Germinate Seeds – FAQs
Learning how to germinate seeds may not be a difficult process, but it’s common for people to have questions about the process, especially when they first start. The following are a few questions surrounding how to germinate seeds.
1. What do seeds need to germinate?
Generally speaking, seeds need three things to germinate, including water, oxygen, and the right temperature. Seeds are in a dormant state until you expose them to these three elements.
2. Do seeds require light to germinate?
Most seeds, including herb and vegetable seeds, germinate best in the dark. It’s easy to make a mistake because seedlings require light to grow, but seeds germinate best with light. As soon as the seeds sprout and seedlings appear, you should put them under grow lights. Some plant species, like coleus or begonias, need light to germinate. If you’re germinating vegetable seeds, they don’t need light.
3. What is the best germination temperature?
Most seeds germinate best when the soil temperature is between 68-degrees F and 86-degrees F. Sticking close to the 75 to 80-degree range will ensure you give your plants the best chance for germination. After they germinate, the best temperature drops to roughly 10 degrees cooler than whatever temperature they germinated at.
4. What is too hot for adequate seed germination?
Ideally, you’ll never expose your seeds to temperatures above 90-degrees F. These temperatures are hot enough to kill the embryo inside of the seed.
Now you know how to germinate seeds with a step-by-step guide and a few quick tips to ensure you’re successful in this process. You can use this article to troubleshoot any issues you run into as well, and maximize your plant growth for the season.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.