How Many Seeds to Plant Per Hole, Pot, or Cell
Want to know how many seeds you should plant per hole or pot? It's a good question with an interesting answer. Epic Gardening Founder Kevin Espiritu answers this common gardening question.
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I recently got an email from an Epic Gardening reader 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?”
Sally
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: germination rates.
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 microgreens and the average germination rate is 90%. If you plant seeds in a 72-plant starter tray with one arugula seed per insert, you can expect only 65 of those plant inserts to actually germinate.
Now imagine you plant multiple seeds at three arugula seeds per insert. Each of these seeds has a 10% chance of failing, so the probability of them all failing is only 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: Plant multiple seeds per hole to increase the chances you have perfect germination rates.
Answer Two: Seedling Selection
Just as 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 as your other plants grow.
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.
So, How Many Seeds To Plant Per Hole?
There are some general rules we can glean from all of the above information. The size of the seed will help you determine how to plant. If we were to average the number of seeds based on all seed sizes, you would plant 2 to 3 overall.
Let’s break it down by seed size, to give you a good sense of the formulas you can use to start seeds. If you’re planting multiple seeds at different sizes, you can simply use this rule to get going.
- Large-sized seeds: 1 seed per hole
- Medium-sized seeds: 2 per hole
- Small-sized seeds: 3 per hole
If you want to get even more exact, you can bust out your calculator to determine exactly how many seeds to plant based on germination rate. Use a ratio to determine how many to plant.
For instance, if you have a seed packet that has an 80% germination rate, and you want to grow 20 plants, you should plant at least 24 seeds, as the remaining 4 will make up the 20% lack of germination expected.
However, since you’ll want to plant in 20 starter cells, you should probably plant two seeds per hole and thin them to the most healthy plants once they’re large enough.
Frequently Asked Questions
How many seeds should I plant in a flower pot?
The number of seeds you should plant in a flower pot depends on the size of the pot and the type of plant. Generally, it’s advisable to plant 2-3 seeds per hole within a container as planting multiple seeds increases the chances of successful germination. But the amount of holes for planting within a flower pot will depend on size and what you’re choosing to grow.
What happens if you plant too many seeds together?
Planting too many seeds together can lead to overcrowding, which causes competition for resources like nutrients, water, and sunlight. This competition results in weak, spindly plants that are more susceptible to diseases and pests. To promote healthy growth, stick to 2-3 seeds per hole and thin the plants as they mature.
Should I plant all the seeds in one seed packet?
It’s generally not necessary to plant all the seeds from a seed packet at once, especially if you have a small garden or limited space. Seed packets often contain more seeds than needed to account for potential germination failures. Planting all the seeds can lead to overcrowding and poor plant health. Instead, consider planting a portion of the seeds and storing the rest in a cool, dry place for future use.
How many cucumber seeds should I plant per hole?
When planting cucumber seeds, it’s recommended to only plant 1 seed per hole. Due to the size of the seeds, overlapping with multiple seeds can hinder germination. You can plant each seed closer together though. Once the seedlings have grown a few inches tall, you can thin them out by removing the weaker plants, leaving the strongest one to continue growing.
How many cilantro seeds should I plant per hole?
For cilantro, you should plant 2-3 seeds per hole. Cilantro plants can grow relatively close together, so you don’t need to thin them out excessively unless they are overcrowded. Planting multiple seeds per hole will help you grow a fuller plant.
How many watermelon seeds should I plant per hole?
When it comes to watermelon seeds, it’s best to plant 1 seed per hole, as with cucumbers. Plant them close together to account for germination rates and thin them when they reach around three inches tall. Watermelons require ample space to grow, so proper thinning and spacing are crucial.
Does one seed equal one plant?
Generally, one seed will produce one plant. However, not all seeds germinate due to various factors like seed viability, soil conditions, and environmental factors. That’s why you should plant multiple seeds per hole—to ensure that at least one seed germinates and develops into a healthy plant. After germination, you can thin out any extra seedlings, allowing the strongest one to flourish without competition.
