It does not have to be complicated to germinate seeds. Plant the seeds in potting soil, cover the seeds lightly, place the pot in a warm place, keep the soil moist and you should see first leaves sprouting in 1 to 2 weeks time.
But needless to say it is not always this easy. There are seeds that seem to want to germinate regardless of what you do.
But then there are also those other seeds that never seem to germinate. And it is not for lack of trying.
But do not give up. Every gardener understands what you are going through. And there are things you can do to give yourself the best possible chance of success.
The good news? It is not about spending a lot of money on fancy machinery or super-duper lighting.
But it will take time, effort and attention to detail. And most importantly, you must be prepared to test, fail and try again.
It is truly the only way to learn what works in the unique ecosystem that is your garden – should it be outdoors, indoors or a combination of both.
Here today we will list what you need to know to successfully germinate seeds to grow strong, healthy seedlings.
Seed germination 101
Most seeds germinate when you get the 3 basics right: water, oxygen and temperature.
Water will soften the seed’s coat to allow the seed to germinate and sprout, oxygen is of course needed for all living processes including germination and warmth to get the germination process going.
And when you start seeds indoors you can provide these 3 basics needs quite easily.
1. Seed germination and water
Seeds need a moist growing environment to germinate and sprout. You keep the soil moist using a spray bottle or by bottom watering your starter pots. Using a quality potting soil will ensure proper drainage keeping the soil moist but not soaking wet.
2. Germinating seeds requires oxygen
We are not talking about adding oxygen using water or air pumps like you would do in hydroponics.
Instead you add oxygen when you use a quality potting soil with good structure and drainage. As the water drains through the moist soil, oxygen is stored in air pockets throughout your pot.
3. Seeds need warmth to germinate:
Seeds need heat or warmth for the germination process to start. Place the pot on a heat mat or on top of a refrigerator or other appliance that generates heat.
If you plant seeds in January when the soil is cold, the seeds will sit in the soil waiting for the correct temperature to germinate and sprout. Not all seeds take well to be planted in January. But quite a few do and please read the linked article to learn more.
Not all seeds germinate like basil and lettuce
Some seeds will germinate as long as you plant the seeds, keep soil moist and warm and mist the soil with a spray bottle every now and then. Basil and lettuce seeds are good examples of the fastest germinating seeds with high germination rate with a minimum level of effort.
But these are exceptions to the rule. For most plants it does pay off to get the details right. Paying attention will give you faster germination, strong sprouts and healthy, compact seedlings. Parsley, coriander (cilantro), chervil, thyme and many more herbs and plants belong to this group of plants where it is important to pay attention to detail.
Or you could simply use the practice of pre germinating or seed sprouting using the paper towel method.
Pre germinating seeds for increased efficiency
When you plant in soil you never know if you are planting healthy seeds. Many seed packets will even state the expected germination rate on the packet. Any number between 50% and 70% is not unusual.
This of course means that half you seeds may never sprout. But on the other hand all seeds could germinate, sprout and grow into healthy plants.
Many gardeners accept this situation and typically sow too many seeds and thin seedlings later as needed. But if you find it wasteful or too uncertain you may instead sprout seeds before planting. And here so called paper towel germination is probably the most popular method.
Sprouted seeds with paper towel gemination
With paper towel germination your goal is to remove uncertainty by only planting sprouting seeds.
Planting seeds in soil leads to a few weeks of waiting for signs of life. Will the seeds grow? Maybe the seeds germinated a few days ago and sprouts will break through the soil surface tomorrow.
There is no way we can know. So we wait.
But there is a better way.
Germinating the seeds before we plant will remove the guess work. If the seeds sprout they are healthy and you will plant them knowing they will grow into healthy seedlings and plants.
Read our article on Growing Microgreens on paper towels for a complete step by step guide on how to build paper towel sprouting system with common household items.
- Place two squares of paper towel on a flat surface
- Water until wet but not soaking (you want damp paper towel, not dripping wet)
- Sprinkle seeds on one half of the paper towel
- Fold the other half of the paper towel to cover the seeds
- Put the folded paper towel in a plastic bag without closing the bag
- Place the plastic bag in a warm and preferably dark place
- First time you need to check back often to make sure paper towels do not dry out
- Use a spray bottle filled with room temperature water to mist paper towel as needed
- In a couple of days you will see germinating seeds with sprouts
- When sprouts are ca 3 mm (1/8 inch) they are ready to be planted in seedling trays
Transfer each seed gently from the moist paper towel as the tiny sprout is very delicate and will break easily. Germinating seeds in a paper towel may lead to the seeds sticking to the paper. If so, it is better to plant the seed attached to the paper than to risk breaking the sprout.
Why pre germinating seeds is a good idea
There are several reasons why it makes sense to sprout our seeds before we plant them in soil.
Saves money: You know that not all seeds will germinate. So why would you plant all seeds in soil? Instead you should only plant sprouted seeds to make sure you do not waste good soil on seeds that will not germinate.
Using the paper towel method you can at virtually no cost pre germinate your seeds on damp paper towels. Now you will be able to only plant sprouted seeds that you know will grow into plants.
Space allocation: You plant a certain number of seeds as you want a certain number of plants for your indoor or outdoor garden. Pre sprouting seeds using paper towels will make it easier to manage the available space in your own garden.
Use older seeds with confidence: Will last years seeds geminate or should you throw them away. Pre sprouting on paper towels is a quick and inexpensive way to check if old seeds are still good to use.
Germinate seeds quickly: No more wondering what is going on below the surface of the soil. Seed starting on paper towels is fast as we know the seed is good as soon as we see that crack in the seed coat.
Better yield planting germinated seeds: With pre sprouting you are only growing seedlings from viable seeds. This will in itself ensure that you get a better yield as unfertile seeds are discarded early in the planting process.
Tips to germinate seeds more effectively
Regardless of type of seed, you should always read and follow the instructions on the seed package to give your seeds the best possible chance to germinate and sprout.
And the tips and tricks listed below hold true for pre sprouted seeds as well as seeds planted directly in soil.
1. Sow seeds at the right time
Some plants need a long time to develop. Tomato seeds and chilli pepper seeds are prime examples of seeds that you need to sow indoors early spring for the plants to have time to grow and mature.
Other plants need to be started indoors and transplanted outdoors when there is no longer risk for frost. These seeds need to be planted 4-8 weeks before for seeds to have time to germinate and develop strong seedlings.
2. Use new or sterilized pots
Used pots can transfer diseases, bacteria and even pests to your new plants. This can however be prevented by cleaning and sterilising used pots before use.
Using new pots is of course easier. But it is far more economical and environmentally friendly to reuse what we already have.
We always reuse all plastic starter pots. Step one is to clean the pots and then to sterilize them using boiling hot water. We always use regular tap water.
Make sure your pots have drain holes – but most starter pots will.
3 Always use fresh soil for seeds
Use fresh soil and look for any specific information on the seed packet. And if there are no specific instructions use a well draining potting soil.
This is not the time to reuse that rejuvenated soil from last season.
Seeds are delicate and you want to give your plant the best possible start. And this includes a good quality potting soil to help your seeds germinate.
4 Make sure the soil you use drains well
Seeds need moisture to germinate. But seeds will rot in wet soil. So you need to find that balance.
If your soil does not drain well you can add perlite or coarse sand to improve drainage and aeration of your soil.
5. Do not press seeds into soil
Pressing seeds into the soil will unnecessarily compress the soil. And you want the soil to be loose and aerated.
Instead place the seeds on top of the soil and then cover with soil if applicable.
6. Water before you plant your seeds
Water your soil thoroughly before you sow the seeds. You want the soil to be moist but not wet.
Watering before you plant will prevent displacing the seeds and also help ensure and control the level of moisture.
7. Cover seeds with plastic
After seeds are planted pots should be covered with clear plastic. Use plastic wrap or a plastic lid or dome to create a mini greenhouse.
Make a few holes to ensure air circulation. If there is a buildup of condensation on the inside of the plastic you need to improve circulation and air flow.
8. Keep moist and bottom water
Do not top water seeds in starter pots.
Instead place pots in trays with water and let the soil absorb water through the drain holes at the bottom.
You can also mist the top of the soil using a spray bottle.
When first leaves sprout you need to start watering less for healthy seedlings.
9. Warm and even temperature (but not hot)
Seeds germinate at room temperature if nothing else is specified on the seed packet.
You can also use heat mats or place the pots on an electrical appliance, like a fridge, that radiates heat.
Heat mats are great to use as they keep an even temperature. When you place the pot on a window sill you may have an ideal temperature during the day. But the temperature will most likely drop substantially at night.
This is why the top of a fridge may be a better place for germinating seeds. But remember that too hot can kill the seed or stress growth and give tall, spindly seedlings.
10 Using pot that is too large
Plant your seeds in starter pots. Using larger pots may seem like a great idea but will just make it harder to control moisture and you risk watering too much or not enough.
Always sow seeds in smaller starter pots and plant 5-10 seeds together in clusters for best results.
11. Too much nutrition
Seeds contain all the energy needed for the seeds to germinate and sprout. Later we may have to add nutrition, but not at the germination stage.
12 Go for warm, moist and dark if in doubt.
Sure, some seeds need light to germinate. But if so, it will say so on the seed packet.
But if you are unsure, always choose to germinate seeds in a dark, warm and moist environment.
Needless to say, the seedlings will need light when the seeds have germinated and the sprouts break through the surface of the soil.
13. Sow seeds in clusters
Do not plant one seed per pot. You cannot expect a 100% germination rate even if you do everything perfectly.
Plant seeds in clusters and watch your seeds germinate and grow into strong bushy plants.
And if too many seeds should germinate, simply cut the weaker seedlings just above soil level. Never thin seedlings by pulling them out by the roots as it unnecessarily risks disturbing the root systems of other seedlings.
14. Prepare seeds one day before
Some seeds take longer to germinate than others. To make germination faster you can soak or gently crush seeds before planting. This is especially true for larger seeds whereas small seeds tend to be easier to germinate.
Coriander (cilantro) is a good example where soaking seeds will help to germinate seeds fast. Gently crushing the seeds before plating can also help germinate seeds quickly.
Helpful resources:
University of Maryland Extension
PennState Extension