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How to Know if Your Indoor Plant Seeds Are Still Good – All You Need to Know

Have you ever found an old seed packet sitting in your junk drawer or a bag of seeds hanging out in the barn? Were you curious to know if they could still be used for your indoor garden? Well, lucky for you, we have all that information here and more.

Topics we will be covering in this article:

  • How quickly a seed’s germination viability can drop over time
  • How to test your seeds to see if they are still good
  • What healthy seeds look like
  • The proper ways to store seeds to keep them healthy
  • How long specific plant seed packets can sit in storage

Keep reading to learn all you need to know when growing your own indoor plants from seeds.

Germination Rate Drop Per Year

Although time isn’t an exact science, the age of an indoor seed is a great way to predict whether or not your plant seeds are still viable and able to germinate. 

Fresh seeds have the potential to germinate nine out of ten times, meaning you will have a 90% chance the seed you plant will grow.

As time goes on, this chance drops and will drop pretty dramatically. Two-year-old seeds will have a germination rate of around 80-90%. Once you hit three years, the chance of germination is around 70%. 

Once you hit four years, the seeds aren’t very effective, providing less than a 50% chance of germination when planted. Seeds are pretty much useless after the five-year marker, and you will probably end up wasting a lot of time if you try to plant them in your indoor garden.

Inside a seed is an embryonic plant. Like all other living organisms, these plants require nutrients and nourishment to grow and survive. Sprouting plants get what they need from inside the shell until their first set of true leaves comes in. 

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But this supply inside the seed won’t last forever. Once the supply is gone, there is nothing left for the plant, which is why seed germination with old seeds is tricky. This is especially true when growing seedlings indoors. The longer these baby plants sit inside the seed, the less nutritional support they will have when you plant them.

Other factors that will reduce the lifespan of seeds include humidity rate, plant species, soil temperature, and storage. High humidity is a significant factor for plants seeds not making it to maturity. Too much heat and moisture will quickly destroy the nutrients available to the plant inside its shell.

How to Tell if Your Indoor Plant Seeds are Still Good

Now that we know the best age for plant seeds to be placed in an indoor garden, it is time to help you determine whether your seeds are still good, especially when you have no clue how old they are.

The Good Ol’ Sinking Test (The Best Way)

Ask any older generation farmer how they knew if their plant seeds were still viable, and you will probably hear about the sink test. While this method originated many years ago, it is still a widely used form of testing and gives pretty accurate results.

To perform a sink test, toss your seeds into a jug of water. The seeds that sink are still viable and safe to plant. Those that float to the top can be scooped up and tossed out because there is little chance they will germinate.

The Sandwich Test

If you have many seeds from the same pack, take 10 of them and place them between two moist paper towels and seal them inside a sandwich bag. The number of seeds that begin to sprout will give you an idea of the percentage rate for the package. 

For example, if only five of the ten seeds sprout, there is about a 50% chance the rest of the seeds will develop as well.

Keep the bag with these seeds in a dry, well-ventilated space at room temperature for the best results.

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Cut It Open

One of the easiest ways to determine if an old pack of indoor plant seeds is still good is by cutting one or two open and getting a clear look inside.

If you cut the seed in half and there is a viable, healthy embryo, the rest of the pack will probably be fine. 

There is an argument about whether or not this is 100% reliable because some newly damaged seeds may not show symptoms right away.

Give It a Good Look Over

Healthy, viable seeds have a hard shell with distinct markings and dramatic coloring. These good seeds will be thick and plump and have easily noticeable ridges.

Unhealthy seeds are flimsy and easy to bend. They will have a dulled appearance, and the ridged areas near the sides are more rounded. 

You do not need to be a seed expert to notice if a seed is bad. When a seed is very old, it starts to look “off” and is actually pretty easy to pick out. This method, however, may not work as well with seeds that are just starting to age.

Purchase the Right Seeds for Indoor Growing

Another crucial step to getting good seeds that are still viable and will grow luscious indoor flowers is simply by purchasing the right seeds. Some seeds are more suitable for indoor planting than others, so make sure you know what you’re looking for.

Get Them From a Reliable Source

When growing plants inside, don’t take a chance on seeds you buy in a department store. You should find a reliable local nursery or specialty store (in-store or online) with a good reputation and access to fresh seeds.

Seed packets will often sit on store shelves for a long time, decreasing their ability to sprout. When growing seedlings indoors, the higher the quality, the better the results.

Find the Best Type of Seeds for Indoors

If you plan to take the time to find out whether your seeds can germinate, make sure you buy seeds known to thrive well in an indoor garden environment.

The best seeds to buy when growing your own indoor garden include:

  • Peace Lilies
  • African Violets
  • Irish Ivy
  • Catgrass
  • Lavender
  • Herbs
  • Nasturtium

The options of seeds will differ a bit depending on where you live and the climate. Do your homework before purchasing any seeds for growing indoors to ensure they thrive. 

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Provide Suitable Soil

Growing plants indoors can be a little tricky because you need to provide all of the best elements required for proper growth and nutrition that your flowers won’t be able to pull from natural elements themselves.

The first step to starting seeds indoors is to use a viable seed. You then have to provide the best environment, which includes using good soil.

Using potting mix is a great option, especially if it is organic. This type of soil will provide you with the best compilation of nutrients to nurture the plant’s growth.

Are Seeds from the Store Good if Past the Expiration Date?

Many people see the expiration date on the package and panic that their seeds may no longer be any good; however, this is not entirely true. 

Many manufacturers have started to reword the expiration date as “best if used by.” Why? Those dates are used more for shelf life and do not determine when the product will go bad.

After the shelf life date is up, your seeds have another year or two left, giving you about a 75% chance or more of plant growth. If you are holding a seed packet that expired four or five years ago, it is probably better to toss them and purchase fresh seeds.

Storage Life of Your Seeds

If you are considering growing an indoor herb garden or an array of flowers, here is a helpful chart with the information provided by the Farmers’ Almanac to give you an idea of what the average storage life per plant looks like.

Herb Seeds Storage Life:

Plant SeedStorage Life
Chives1 Year
Parsley1 Year
Oregano2 Years
Dill3 Years
Sage3 Years
Savory3 Years
Thyme3 Years
Fennel4 Years
Basil 5-7 Years
Cilantro 5-7 Years
Catnip5 Years

Flower Seeds Storage Life:

FlowersStorage Life
Aster, Delphinium, Geranium, Larkspur, Verbena1 Year
Baby’s breath, Clarkia, Coleus, Dahlia, Fox Glove, Inpatients2 years
Bachelor’s Button, Amaranth, Cosmos, Daisy, Hollyhock, Lobelia, Nicotiana, Petunia, SnapDragon3 Years
Ageratum, Alyssum, Celosia, Dianthus, Poppy4 Years
Calendula, Nasturtium5 Years

For information about seed life for growing vegetables and more, refer to the Farmers’ Almanac for reliable and valuable information.

Summing Things Up

There are multiple ways to check your seeds to see if they are still viable for growth. However, making sure you purchase seeds from a reputable source and knowing what to look for in a healthy specimen gives you a higher chance of successfully planting seeds indoors and growing seedlings that turn into healthy plants.