Most of us have some leftover seeds from the garden season. Let’s have a look at the best way to store them in our homes to keep them as viable as possible for future sowing.
If you are new to starting plants from seed, Seed Starting for Beginners have everything you need to know to get started.
Storing Seeds at Home
We know seeds can last longer if stored properly but what does this mean for keeping seeds in our homes?
What’s the best way to do this with the conditions we have?
First of all, when it comes to seed storage, moisture is the enemy. If you are saving your own seeds, be sure you are starting with nice, dry seeds.
Optimum Seed Storage
The lower the temperature and moisture levels, the longer most seeds stay viable.
See this entire seed storage article for details.
Best temperature | 32-41°F (0-5°C)
Most fridges are in this range.
Also, room temperature (70°F/21°C or lower) is fine for short-term storage (1 year).
Store dry seeds and keep dry | Relative humidity below 50% | Keep away from light
Paper Envelopes | In sealed jars with silica gel pack if moisture is an issue
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Looking at the science, the best way to store seeds is actually a pretty complicated topic for the long term.
But, from a gardening perspective, it usually isn’t worth a complicated answer.
In the agricultural industry, where there’s millions of dollars riding on seed storage, or with seed banks like the Global Seed Vault (read all about it here) where they are storing critically important seeds for decades, it makes sense to invest in infrastructure to provide optimum storage conditions.
But, for us home gardeners keeping small amounts of seeds from one year to the next, it’s usually fine to work with what we have.
For starters, time is on our side since most seeds stay viable in their first few years. Even if storage is less than optimum, it’s usually good enough for the short-term.
Drawer, Fridge or Freezer? Basement, Bedroom, or Garage?
In the short term, any differences between storage methods are likely minor.
If we’re just storing seeds until next spring and maybe even the year after, putting them in a paper bag or an envelope in a drawer in a bedroom or some other room in your house that maintains a moderate temperature, lower relative humidity (the lower, the better) and doesn’t expose the seeds to sunlight should be fine.
That said, some seeds just don’t store well no matter what you do. Your seed packet may tell you what to expect.
I keep mine sorted by Best Before date to be sure I use them up in the right order.
We also get mice in parts of our house so I like to keep the seeds where they will not find them.
Harrington’s Rule—Storage Temperature Matters
In the world of botany we have Harrington’s Rule for seed storage.
The cooler and drier, the better.
Not all seeds, but generally storage life:
- Doubles for every 10-degree Fahrenheit (5°C) drop in temperature and also
- Doubles for every 1% drop in seed moisture content.
We probably aren’t going to do much about the moisture content of our leftover seeds, nor will we have a way to measure it, but temperature is something we can manage.
SEED SHOP: Organic Seeds at Botanical Interests
Room Temperature Versus Fridge Temperature
Your typical room temperature is around 70 ° F (21 °C) and your fridge is around 40°F (4°C), so that 30-degree difference should significantly extend the life of your seeds over the long run.
But, in the short-term (a year or so with fresh seeds), it doesn’t make much difference.
Freezer Storage Pros and Cons
With seed banks, their standard storage temperature is around -18°C or just under 0°F which also happens to be the temperature inside many home freezers.
So the freezer may seem like an even better place to store your seeds—and it may be if you are planning to store the seeds for many years—so long as moisture levels are low.
The natural cycle of most seeds we grow is to mature and dry out. Their metabolic rate lowers and they stay dormant until germination is triggered.
One group that cannot tolerate cold or freezing conditions includes seeds from tropical trees, which are usually quite large seeds (think avocado), so check if you are uncertain. These retain higher moisture levels causing them to ice up and die when temperatures are too low. So exclude this group.
Otherwise, you can use the freezer for long-term storage if you are confident moisture levels will remain low.
I stick to using the fridge or a room in our house for short-term seed storage since moisture levels are always the wild card and time is on your side.
Click here to jump back up to the Optimum Seed Storage info.
And there you go.
There are lots of complexities to the topic but ultimately, like many things in gardening, we may not have to put much thought into it because conditions just happen to be right.
~Melissa the Empress of Dirt ♛
Are These Seeds Still Good?
Seed Viability and Germination Test
- First, follow any recommend preparations for sowing such as scarification (roughing up seed coat) or stratification (e.g. pre-chilling).
- Place 10 seeds an inch apart on moist paper towel, coffee filter, or cloth. Fold over and insert in labelled plastic bag.
- Keep in warm, dark place. Most need a 65-75°F | 18-25°C temperature range. Do not allow paper towel to dry out.
- After expected germination period (number of days), check how many seeds sprouted (e.g. 8 out of 10 = 80% germination rate). You can sow any seeds that have germinated. If nothing sprouted after an extra week, the seeds are probably toast.