Germinating Seeds Quickly - Complete Guide (2024)

Starting seeds is one the most exciting and enjoyable parts of gardening and you can do it in winter. Each seed pack contains little miracles that in your hands will develop into beautiful mature plants, provided you follow the simple steps outlined in this post.

I have personally germinated over 2,000 different varieties of plants using the methods in this guide. It is much easier than you think and the tricks and procedures detailed here will work for vegetables, flowers and even trees. Grab those seed packs and let’s get started.

Seeds Are Living

Most seeds are small, hard and black. They look completely dead but looks are deceiving. Seeds are living organisms and you need to treat them as such. Even though they are dormant they are absorbing oxygen, giving off carbon dioxide, and slowly using up their stored food reserves.

They continually monitor their environment waiting for ideal conditions to break dormancy and germinate. As a gardener, your goal is to provide that environment.

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What’s Inside a Seed?

A seed has everything it needs to develop into a plant. Each one has a protective seed coat which contains an embryonic (baby) plant and a starchy food supply. As the embryo grows, it lives off the starch until it has made its own roots and leaves. These are then used to make more food through photosynthesis.

What Is Seed Germination?

Seed starting is the process of growing plants directly from seeds. Most people start seeds in soil and they equate “germination” with the appearance of a seedling above the soil level, but that is not correct. Germination is defined as the point when a root, called a radicle, emerges from the seed. In many cases this differentiation is not important but it can be critical when you are trying to understand why a seed is “not germinating”. Just because you did not see green growth above the soil does not mean the seed didn’t germinate.

The Germination Process

The dry seed is living, but dormant. The first thing that needs to happen is the absorption of water. This starts a chain of chemical reactions that trigger the embryo into growth. The next step is the formation of a root. As it elongates and starts forcing itself out of the seed, the first stem and leaves start to grow. The root comes out first and starts growing down, soon followed by the stem that grows up. Once the stem is above the soil level it opens up the first leaves called the cotyledon leaves.

The process is a bit more complicated than this and you can read all about it in my book, Plant Science for Gardeners, which contains 3 chapters about starting seeds.

Which Seeds to Germinate Indoors?

You can germinate all seeds indoors and if needed, you can use the fridge to give them a cold treatment. Starting them indoors is a better option than starting outside because you have better control over conditions, you can start them early and you will have a higher germination rate (i.e. more seeds germinate).

What Seeds Need to Germinate

Seeds need a few basic things to germinate: water, warmth, light and air. How do you know the exact conditions they need? Start by reading the seed pack and follow its instructions. If you don’t have a seed pack, look up the plant on the best online germination guide by ORGS. It contains instructions for thousands of species.

Water

The first step is the absorption of water. This can be done by soaking seeds, placing them in wet soil (potting media) or by putting them on a wet paper towel. They all work equally well.

Temperature

Every seed has a preferred temperature for germination. If the temperature is above or below this ideal, they germinate slower. At some point it is too cold or too warm and germination stops entirely. The good news is that most germinate just fine at room temperature, 65-75°F (18-24°C).

Many seeds also need a cold pretreatment before the germination process starts, but even these germinate at room temperature after the cold pretreatment is complete.

Light

Some seed doesn’t care about light, while others need to have either light or dark. As a general rule, 90% of seeds will germinate in light so if you are not sure, give them some light. This does not have to be high light. Normal room light is adequate.

Once they germinate, seedlings need a good source of light to grow properly and ideally they get that as soon as little green heads show above the soil line.

Air

Remember that seeds are alive and all living organisms need oxygen. The amount they need is quite small and even seed packs provide enough air for them.

Seedlings need more air especially at the roots and that is why you want to use a light airy potting media.

How to Germinate Seeds Faster?

Each type of seed germinates at its own pace. The fastest germination happens when conditions are perfect for a particular seed type. If you provide these conditions, there is very little you can do to speed up the process, except with the special chemical or hormone treatments discussed below. It takes as long as it takes.

I see a lot of claims about speeding up this process but they are myths. Here are some of them.

• Paper towel method is faster – false.
• High temperatures are faster – not if you are already using the correct temperature, and a temperature that is too high can slow down and even stop the process.
• Water with soapy water – soap is toxic to seedlings.
• Soak seed in diluted alcohol – it can increase or decrease the % germination of grass seed, but there is no effect on the speed of germination.

Old Seed

I mentioned above that seeds are alive but that is not entirely correct. Just like any living organism, seeds will eventually die and dead ones look just like live ones. They can die from old age or poor storage conditions. Some seeds like onions are naturally short lived and are mostly dead after 1 year. Tomato seed lives for at least 10 years.

Storing seeds dry and cool will extend their life. Don’t store in plastic because it traps moisture which shortens life-span. Use easy to make paper seed envelopes instead. Store in the fridge, but not in the freezer which will damage seed that is not fully dried.

As with all rules about seeds there are exceptions. Some need to be stored wet and if purchased from a reliable seed house, these will be in moist sealed packages. Trilliums are a good example. Dry stored seed lasts about 6 months, while moist packed seed lasts several years and germinates much faster.

Not every seed in a package dies at the same time. A new package might have a germination rate of 90% which means 10% of the seeds are dead. After three years that rate might drop to 70%, and after 10 years it might only be 20%. For most gardeners, even 20% will give you enough plants – just start more seeds to compensate.

Here is a list of the life-span for some common vegetables. For flowers, have a look at the lists provided by Johnny’s Selected Seeds.

Is My Seed Viable? – The Float Test

The float test is commonly prescribed for testing the viability of seed i.e. are they alive. You put seeds in some water and see if they float. The sinkers are alive and the floaters are not. Problem is, the test doesn’t work. Some types of seed always float and will germinate just fine. And some dead seed always sinks. For a detailed review of this test see Floating Seeds in Water – Is This a Good Seed Viability Test?

A much better test is to use the paper towel test which will actually show you results. If you use 10 seeds for the test, you can easily calculate the germination rate (9/10 = 90%).

How Quickly Do Seeds Germinate?

I see a lot of websites that say seeds germinate in 1-2 weeks. That is simply not true in many cases. The time needed depends on many factors and some seed just take a long time. Annuals and vegetables tend to germinate quickly. Many perennials are slower, and trees are slower still.

Peppers are a slow germinating vegetable with green bell peppers germinating in about 1 to 3 weeks while hot peppers can take 4 to 6 weeks.

As seed ages they tend to germinate slower because it just takes longer to wake them up. Temperature has a lot to do with it. At ideal temperatures, fresh tomato seed germinates in 5-7 days. Older seed, or seed at lower temperatures can take 10-14 days.

Claims that, “the warmer the environment, the faster the germination” are wrong. Cucumbers for example, won’t germinate below 61°F (16°C), germinate best at 95°F (35°C) and stop germinating at temperatures over 104°F (40°C). The best temperature is the right temperature, not the warmest.

Clematis take 1 – 8 months. Peonies need several months to a year. The longest germinating seed I have ever worked with was Halisia carolina, a beautiful white flowering shrub, that took 5 years to germinate and I got 3 plants out of it.

Don’t be discouraged if it takes longer than you expect and don’t give up too quickly.

When Should You Start Seeds?

It is winter and you can’t wait to start gardening so you start some seeds indoors. They germinate and grow beautifully and by mid-winter they are too big for your indoor space. That is a common mistake you should avoid.

For a detailed list of start times for both vegetables and flowers see When To Start Seeds Indoors.

A Simple Seed Starting Rule

Follow the instructions on the package. If you don’t have a package, start seed 6 weeks before your last frost date. For annuals and perennials you can extend this to 8 weeks. If seed germinates in 2 weeks, you have 4-6 weeks of actual growing time before they go outside and that is adequate time for seedlings to put on enough growth to be outside.

Seeds That Germinate Easily

If you are a new gardeners, start with seeds that are easy to germinate. That includes almost all vegetables, many common annuals and some perennials. Look up their germination requirements before you buy them so you know they don’t require any special treatments.

As you gain experience, try the more difficult ones.

What is Dormancy?

Many people misunderstand the term dormancy and think it only applies to seeds that are difficult to germinate, but that is not true. All dry seeds are dormant. They won’t germinate without some pretreatment. The pretreatment causes internal biochemical changes that lead to a point where it can germinate, i.e. produce a root and shoot. The pretreatment is used to overcome the condition of dormancy. For more on dormancy see, Seed Dormancy – What is It and How do You Break it?

Overcoming Dormancy

The pretreatment for many seeds is just the addition of water. However, other seeds need or benefit from other pretreatments as discussed in the following sections.

Soaking

Soaking does two things. Some seed is covered with an inhibitor the mother plant puts on the seed to slow down germination. For example, the pulp of most fruits contain a chemical inhibitor and soaking can remove it. This is usually not required for purchased seed since the vendor has already done this for you.

Soaking also allows the seed to absorb water but this is not really required for any of the seed starting methods described below since they all add water as part of the method. Some claim that “soaked seeds” germinate quicker, but the difference is minimal. Here are some test results for pea seeds with and without soaking.

Scarification

The seed coat is the hard outer layer of the seed and the radicle has to penetrate this in order for germination to take place. Many seed coats are thin enough that this is not a problem. Thicker coats may be softened up with a water soak but in some cases the coats are so thick (e.g. walnut) they need extra help called scarification.

There are three easy methods gardeners can use to scarify a seed: sandpaper, file and nail clippers. These are used to make a small hole in the seed coat and are fully demonstrated in this video: Seed Scarification Speeds up Germination (compare methods).

Stratification

Stratification is a fancy name for temperature cycles. Many seeds need a cold period to trigger the embryo into growth. This is why many seeds from temperate regions only germinate in spring after they have experienced a cold winter. As gardeners we mimic this is the fridge.

A common myth is that storing dry seeds in the fridge will stratify them. This is wrong. Stratification has to take place after the seed has absorbed some water. Therefore you have to wet the seed first and then give it a cold treatment.

I usually stratify for 30 days and then see if they germinate. If not, stratify for another 30 days. Older seed needs longer stratification periods.

For full details on stratification see the video: Seed Dormancy – Use the Right Pretreatment for Fast Germination.

Chemical Treatment

A number of chemicals are also used to pretreat seeds, including hydrogen peroxide and fertilizer.

Hydrogen peroxide has been shown to be useful for some seeds, but prolonged exposure, or exposure to high concentrations will kill the seed. Use this method only if required by the germination instructions.

Instead of water for the initial exposure, some people use fertilizer thinking that the added nutrients may help the seedling grow. Scientific studies do show that seeds absorb nutrients along with the water but evidence to show that the nutrients result in healthier plants is still lacking.

Hormonal Treatment

Gibberellic acid, known as GA3, is a natural plant hormone that can be used to speed up germination. It is mostly used on seeds that are difficult to germinate or ones that take a long time.

Glaucidium Palmatum is a slow germinating perennial so I tried using GA3 on it. Without the hormone germination takes 2 months and with GA3, they sprout in 1 week.

The way I use GA3 is demonstrated in this video: Gibberellic Acid – GA3 – Germinate Seeds Faster – How and When.

Best Method to Germinate Seeds

What is the best germination method? There isn’t one. Each method has some pros and cons. Here are three of the most common methods.

Traditional Soil Method

This is the method you are probably most familiar with. Take some soil, put it in pots, add the seed, water and wait. It is relatively simple, supplies are easily available and it has been used for many years. This is my preferred method for very tiny seeds. See detailed description below.

Pros:

• Simple method and seedlings do not have to be moved once they germinate.
• Easiest method for very small seeds.

Cons:

• Can’t see germination take place. If no seedling develops you don’t know if there was a germination problem or if the germinated seed rotted in the soil.
• You generally plant several seeds in each pot to make sure you get at least one seedling, and then you have to thin the excess.
• Stratification is more difficult to carry out in pots – who wants dozens of pots of soil in the fridge?

Paper Towel Baggy Method

Seeds are placed on wet paper towels and placed in baggies until germination takes place. Once the root emerges, they are planted in pots containing soil.

Many people claim that this method is faster but that is a myth. The seed does not know if it is in soil or laying on a paper towel. Given the same environmental conditions, seeds will germinate at exactly the same speed in both methods. See detailed description below.

Pros:

• You can easily see the seed developing, especially if you use my improved baggy method.
• Stratification is easy. The baggies can be put in the fridge and moved between warm and cold as many times as required.
• Only germinated seed is potted up so each pot will have one seed. This is a benefit if you only have a few seeds.
• Great way to check old seed to see if they are still viable.
• No need to thin seedlings.

Cons:

• Two step process. Germinate in paper towel and then move to soil.
• A bit more work.
• Moving very tiny seeds from paper to soil can be tricky, but it can be done using my flip method.

Winter Sowing

This is probably the easiest way to grow seeds. Take some clear or white containers, add soil, water and place outside in the middle of winter. Let nature do all the work. The method is fully described in this video: Winter Sowing Seeds in Containers.

Pros:

• Easiest method of all, and can be done outside in winter.
• Produces very short, tough plants.
• Grow lights are not needed.

Cons:

• May not work for non-hardy plants, although tomatoes work fine in US zone 5.
• Can’t see the actual germination process.

Germinate Seeds in Soil

Follow these steps for germinating seeds indoors.

Growing Media (Seed Starting Mix)

Although I have used the word soil in this post, real garden soil is not used for starting seeds indoors. Instead use a soilless mix. What is that? A soilless mix is usually made up of either peat moss or coir, with a little added perlite. You do not need a special “Seed Starting Mix” which is just an expensive version of a soilless mix or potting mix. Use the same material you use for potting up house plants.

Pots, Containers

Get some plastic flower pots or other recycled plastic containers such as yogurt containers. Make sure they are large enough so you don’t have to move seedlings before they go outside. If you use recycled material, punch some holes in the bottom for drainage.

Don’t use these items which are frequently suggested – they don’t work.

• Eggshells or egg cartons
• Jiffy Peat Pellets
• Ice cream cones

Planting seeds

Fill each pot with soilless mix, press it down firmly and add your seed. For insurance, you can plant two seeds per pot. If both seeds germinate, snip one off and let the other grow.

How deep should you plant? That depends on the size of the seed. Make a hole that is twice as deep as the diameter of the seed and cover it. Very small seeds should just be sprinkled on top of the media without being covered.

Water and Cover

The next step is to water the pot. If the seed is large you can simply water from above just like any other houseplant. Don’t get the soil too wet.

For small seed it is better to water from below so that the seeds are not washed too deep into the soil. Set the pot in an inch of water and once the surface is wet (it will look darker) remove the pot and let excess water drain out.

In both cases, cover the pots with a plastic bag or shrink wrapped plastic to create a miniature DIY greenhouse, or use a humidity dome. The goal is to keep humidity up and reduce evaporation. Unless the seeds take a long time to germinate, you won’t need to water again until you see seedlings, but don’t let the pots dry out. Don’t keep them too wet either or you might rot the seeds.

Light and warmth

Give the pots some light, but normal room light is sufficient. A warmer spot will usually speed up germination. The suggestion to place these on top of the fridge used to work 20-30 years ago in older fridge designs, but it does not work today.

Once you have germination, uncover the pots and expose them to normal room humidity. Seedlings require about 12 to 16 hours of light a day. Intense light is necessary to prevent spindly or leggy seedlings. If you are growing under lights, ensure the light source is 4 to 6 inches above the plants. In a sunny window, turn the seedlings regularly to avoid leaning.

Do You Need a Heating Mat?

Unless you are trying to germinate seeds in a really cold area, you do not need a heating mat. However, it will speed up germination if the preferred temperature is higher than your room temperature. It is useful if you do all your seeding in a cold basem*nt.

For example, both pepper and eggplant germinate slowly at room temperature but fairly quickly on a heating mat.

IMPORTANT: Once seeds germinate, they should be removed from the heating mat. Germinate warm; grow cool.

Germinate Seeds in Paper Towels

I germinate most seeds using this method and I have developed an improved baggy method. Seeds are placed on paper towels or coffee filters, and water is added to make the paper just wet. Then the seeds and paper are put into a plastic bag. The bag keeps the water from evaporating and keeps humidity high.

Once the seeds germinate, they are moved to a soilless mix in pots, as described above for the soil method.

This method is ideal for stratification because the baggies take up very little room and are easily moved in and out of the fridge, or in and out of light. If seeds need to germinate dark, just keep them in a drawer.

After Germination

Germination is just the first step in growing adult plants. Now it is time to learn about the critical process of getting seedlings to adulthood, including:

• Watering Seedlings
• Preventing Disease
• Fertilizing Seedlings
• Thinning Seedlings or Pricking Out Seedlings
• Transplanting Seedlings to Pots
• How to Harden Off Seedlings
• Transplanting Seedlings Into the Garden

All of these topics are covered in my post called, Seedling to Adulthood – Secrets for Growing Mature Plants From Seed.

Or if you prefer video, watch Start Any Seed Including Perennials, Trees, Shrubs and Bulbs – Part 1 and Start Any Seed Including Perennials, Trees, Shrubs and Bulbs – Part 2