How Many Seeds to Plant Per Hole, Pot, or Cell?
I recently got an email from Sally with a familiar question. It’s the same exact question that I had when I was a beginner gardener and wondered how to start seeds:
“I’m sure this is a silly question, but I always see it recommended to plant more than one seed per hole. But why? I just got a seed starting kit with some seeds and want to make sure I’m using them efficiently. Can you help me out?”
It’s a great question, Sally! Understanding the answer to this question will improve your understanding of gardening and seed starting in general, because the answer hinges on an important concept: seed germination.
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Answer One: Seed Germination Rates
Not all seeds are created equal. Some plant species have higher germination rates than others. Even within a single plant type, some of the seeds are older than others, causing the germination rate to go down.
Imagine you’re growing arugula and the average germination rate is 90%. If you plant a 72 plant starter tray with one arugula seed per insert, you can expect only 65 of those plant inserts to actually germinate (72 x 90%).
Now imagine you plant three arugula seeds per insert. Each of these seeds has a 10% chance of failing, so the probability of them all failing is 10% x 10% x 10% = 0.1%. This means that you are 99.9% likely to have the seeds in that cell germinate. So in a tray of 72 inserts, it would be extremely unlikely you would have any seeds not germinate — barring other factors that affect seed germination.
In short: Planting more seeds per hole increases chance you have perfect germination rates.
Answer Two: Seedling Selection
Just like not all seeds are created equal from a germination standpoint, not all seeds germinate equally. Sometimes you have a seed that shoots off like a rocket and becomes too leggy. If this was the only seed in your insert, you’d be forced to use it.
By planting 2-3 seeds per cell, you allow yourself to luxury of choosing the seedlings that look the strongest. All you have to do is determine which one you like the most, then snip off the other seedlings to kill them.
Exceptions to The Rule
Like most things in gardening, there are always exceptions to this rule of 2-3 seeds per hole.
If you’re planting large seeds like cucumbers, melons, or pumpkins, you should only use one seed per hole. However, you can still plant seeds close together and then thin them out once they’ve established themselves. You just want to avoid crowding these large seeds together so you don’t mess up the germination process.
If you’re growing certain herbs (cilantro, dill, basil), you can get away with planting multiple seeds per hole and leaving them all there as they germinate. These plants can handle being planted right next to each other and basically become one larger, bushier plant.
Now that you know how many seeds to plant per pot, you have a deeper understanding of seed germination in general. For more on seed starting, please check out the simple seed starting for hydroponics guide.
A common question I get by email is, "How many seeds should I plant in each hole or cell?". It's a good question with a great answer — read on to find out!
Number Of Seeds Per Hole: How Many Seeds Should I Plant In A Pot
The age-old question from beginning gardeners is often how many seeds should I plant per hole or per container. There is no standard answer. Several factors figure into seed planting numbers. Read on to learn more.
How Many Seeds Per Hole?
The size and age of the seeds to be planted figure into the equation. So does the expected germination rate for each type of seed. To learn the expected germination rate for each type of seed, it is normally found in the information on the back of the seed packet, or you may search the online.
Age of the seed is a factor too. We expect seeds to be fresh when packaged, but after that our only indication of their true age is the expiration date on the packaging. Some seeds continue to be viable past the date when they expire.
Perhaps we have seeds left from last year’s plantings. These seeds will possibly still sprout. These are situations where we will increase the number of seeds per hole. Some gardeners always plant at least two to three seeds per hole, just in case.
Number of Seeds Per Hole When Planting
Depending on the rate of germination and how fresh tiny seeds might be, plant two or three per hole. Some herbs and flowering ornamentals grow from tiny seeds. Often, all seeds will sprout, but this is not a problem with these plants. You may leave them all to grow together. If all seedlings that sprout are not top quality, snip them off at the soil line instead of pulling, leaving the best seedling in place.
When planting medium sized seeds that may be old, make the holes slightly bigger if you’re planting two or three. Don’t exceed three seeds per hole. If more than one germinates, snip off extras at the soil line also. This prevents disturbance of the seedling roots on the one you’ll continue growing out when thinning.
Don’t add more than one large seed to a hole. If you’re attempting a specific number of plants or just want a fuller pot, plant the large seeds closer together. You can snip or pull out those that are too close. Remember, seedlings need good airflow around them to avoid damping off.
Other Factors That Affect Seed Planting Numbers
Some seeds have a thick outer shell. These sprout more readily if soaked overnight or nicked with a sharp tool. Plant these afterward, according to size.
Some seeds need light to germinate. If this is the case with the seeds you’re planting, don’t allow extra seeds in the hole to block others from getting light. You may cover seeds with a light layer of perlite or coarse sand to let the light through.
Growing plants from seed is the best way to get unusual varieties. It is less expensive than buying all your plants. Now that you’ve learned the basics of how many seeds per hole to plant, you’re one step closer toward successfully growing your plants from seed.
The age-old question from beginning gardeners is often how many seeds should I plant per hole or per container. There is no standard answer. Several factors figure into seed planting numbers. Click this article for more information.