Germination tips for pepper seed

Germinating pepper seed requires tropical conditions. This makes sense if you remember that peppers originally came from the equatorial regions of South America. Peppers are also perennials (grow year after year as compared to an annuals which grow, produce seed then die each year). In temperate climates peppers can only be grown as annuals since they cannot survive frost and will die each winter.

In temperate climates you MUST conform to the pepper seed’s need for warm tropical conditions. If you do not you will get poor to zero results. If you are not willing to do this then give up now – save the expense of embarking on what will certainly be a doomed endeavor.

Easy versus Hard to Start Varieties

There are peppers have been around for a long time and have been bred for growing in temperate climates. These as a rule are more forgiving of non-optimum germinating conditions and also germinate faster. On the down side they tend to be somewhat ordinary – usually available at the grocery store.

Other peppers can be very difficult to germinate. Some not only require tropical warmth but also need to pass through the digestive tracts of birds to stimulate germination. This adaptation allows for seed to be spread far and wide by birds in their native environment but leads to difficulty for us who want to bypass the bird part of the process. Fortunately there are substitutes for the bird pretreatment which are discussed below.

Temperature Requirements

Whether or not the pepper seed needs the bird pretreatment, it is imperative that the seed get constant
tropical heat in the range of 30 degrees C (86 degrees F) for as long as it takes to germinate the seed. Yes, you can get some seed to germinate at lower temperatures, but the success rate falls off rapidly with decreasing temperatures (even more so with difficult varieties). In additions, the time required to germinate seeds grows with lower temperature.

Time required for germination

This is controversial and highly variable. Some state that “good” seed will germinate under optimum conditions in one week. There is some justification for this since predictable germination results in predictable timetables and lowers costs for commercial growers. For the commercial growers a lack of predictability is “bad” for the bottom line. Some of my seed does indeed germinate in one week or so. Generally the more generic the seed the more it tends to follow a predictable time frame. But some of my seed doesn’t follow any predictable time table at all. I have had some seed take up to 3 months to germinate even when kept at optimum temperature the entire time!

So does long germination time mean bad or less viable seed? I don’t think so. On many occasions I have had multiple plantings of a particular variety sit there and do nothing for months. Then one sprouts. The next day two more sprout. The next day another one sprouts. This is too coincidental to be happenstance. There must be some condition in seed formation, drying, or storage that affects the germination time significantly. Also, I have not noticed any difference in overall health or eventual fruit set between plants that sprout late versus early.

I find that a dormancy period from harvest & drying seed to planting is needed for timely germination. Fresh harvested seeds almost always don’t germinate at least a couple months (if at all). The same seed saved for a year has no problem the second time around. This is just one parameter. It is not the whole story.

So how do I germinate all my seed?

I plant a lot of peppers. I start around 64 six-packs (those thin black plastic seedling containers with six cells per unit) which makes for roughly 400 plants. I eventually plant in the ground less than ½ of those – the extras allow me some redundancy if peppers fail to germinate, damp off, or get destroyed by wild animals/kids, etc. It also allows me to give away quite a few seedlings every year (after I cull out the best).

The pepper seed is planted only in high quality sterilized potting soil. In my area steam sterilized “Super Soil” is the cheapest acceptable soil when it goes on sale in the big 2 cubic feet bags.

I put 8 six-packs (64 plant cells) into a watertight flat [six-packs and flats source]. The flats are kind of flimsy so I built wooden trays out of 1 x 2’s with wooden lath strips nailed across the bottom. The trays are built to fit the standard flat size.

One more thing: Each cell of each six-pack is likely to sprout at different times. The germination area is usually crowded and dark while the seedling area is elsewhere, bright, but colder [see Seedling care page]. Once a seed has sprouted it must be moved under the lights separate from the other cells in the six-pack which haven’t sprouted. I accomplish this by saving split and other wise damaged six-packs from years past and cutting them up into individual cells. I place one of these individual cells into each cell of a good six-pack then fill with soil. Now I can remove one cell contents easily with no damage to the tender germinating seed and move to a new six-pack cell under lights. It doesn’t matter that the cell I’m transferring is in a split or damaged state since it only is moving a few dozen feet and will be held together once again by a good six-pack in its new location.

Now that I have 8 or so waterproof flats (which I can water indoors since they won’t leak) I must keep them warm. I’ve used two ways:

The old way

I heated a small room. This is both expensive and a hassle but it works. The best room in my house is the bathroom for several reasons. It is small, not occupied for long periods (it’s going to be hot in there), and because of the tile it tends to act as a heat reservoir which keeps it warm as doors open briefly. [Tiles normally feel cool to the touch because they are cooler than body temperature and require a lot of heat energy to raise their temperature. But once the elevated temperature has soaked in, they hold a lot of heat energy and re-radiate it to keep the room warm when the door is opened].

To heat the room I used an ordinary space heater. The heater (like most) had a manual temperature adjustment which shut off the heater at some temperature based on a knob position, and the heat setting of the room was constantly monitored and adjusted by me based on a strategically placed thermometer. I think that having the heat storage characteristics of tile in the room helped a lot because it resulted in temperature changes slow enough that I wasn’t always chasing the optimum temperature (classic servo control loop instability).

The new way

Having our only bathroom heated to 85 degrees round the clock for 2-3 months per year didn’t sit well with my family. I had to do something else. Each flat of eight six-packs is roughly 1 foot by 2 feet, and stacked vertically I could easily fit 9 flats one above the other in 6 feet of vertical space. Using the flats as a template I built an insulated wooden chamber around them extending up roughly 7 feet high. A large door allows access and there are wooden rails to hold each flat one above the other spaced at about 7 inches apart.

The heat is provided from 4 each 100 watt light bulbs mounted in a metal tool box on the bottom of the chamber with forced air circulation via a fan and ducting. The lights are servoed on/off to maintain temperature to 30 degrees C using custom electronics. Average power consumption is less than 125 watts, and the whole chamber takes up 4 square feet of floor space.

If you are going to design you own box please pay particular attention to and address the danger of fire – particularly so with any possible servo control loop failure modes. No amount of pepper growing is worth the risk of burning down your house.

Possible other Ways for Small Growers

I knew you would ask this – unfortunately I don’t do anything in a small way, so I have no experience with this. Here is what others have suggested:

1) “Heat mats”: These are commercially available from many ordinary mail order gardening supplies and seed sources. They heat a small area to a set value (usually just one flat’s worth). They are also expensive (but not when compared to heating a small room for one flat!).

3) The “Top of the ‘Fridge”: According to folklore, the top of the fridge is supposed to be warm. I don’t know what decade this tidbit of knowledge originates from, but I have never seen a ‘fridge that has a warm top. Of course this is easy to test [do this in the winter cause that’s when you’re going to need this]:

  • A) Move all the stuff off the top of the fridge.
  • B) Put your hand there, and think: Is this warm? Nope.
  • C) Wash your hand (and wash the ‘fridge top while your at it).
  • D) Put all that stuff back
  • E) Go to the next suggestion.

4) The “TV Top” (The “Cable Box” top is a second possibility): This is nearly always warm in my house, at least from after school through the 10 O’clock news. But there are problems:

The TV is off at night and off during the day. And when its on, it is too warm. When its off it is too cold. I placed a thermometer with some seeds that I was test germinating and found that the temperature was very hard to control. Some sprouting seeds were killed by temps in excess of 105 degrees. One thing is for sure, using this method requires careful monitoring of the temperature with a good thermometer.

Seed Pretreatment

Some varieties of seed have a very hard coat that takes a long time break down and therefore slows germination. These varieties have probably evolved this characteristic to allow partial digestion while passing through the digestive tracts of birds. The birds digestive process softens the seed coats and tends to spread them over the countryside at the same time.

Some seeds that fall into this category are chiltepines & bird peppers. If these seeds are planted without simulating the bird digestive tract they take a very long time to germinate – sometimes months even at elevated temperatures.

There are a couple techniques that simulate the seed coat softening step without the cooperation of birds. I have tried both of the following treatments as well as an untreated control group side by side from the same lot of seed. The pre-treated seed by far germinated quicker than untreated seeds.

What I don’t know is whether “easy to sprout” seeds such as commercially grown bells or jalapenos benefit from the same pretreatment.

1) Ordinary household Bleach (Sodium Hypo Chlorite):

Be sure to use the ordinary stuff – make sure it doesn’t have other stuff added in it. I soak seeds in a 10% bleach to 90% water solution (by volume) for 10 minutes, rinse well, rinse well again, then plant. This works well and has the advantage of also killing seed borne diseases in the process. Bleach is also available everywhere, as opposed to the next pretreatment:

2) Potassium Nitrate (KNO3, also called Salt Peter):

I had better overall success with KNO3 than with bleach, but not enough better success to completely dismiss statistical variability. Potassium Nitrate used to be (and maybe still is) mined then refined from bird guano (if you don’t know what guano is look it up). Salt Peter is a chemical that has many uses, some of which are of concern to local and national authorities. Therefor it is often difficult to obtain.

One teaspoon bags cost one dollar, but if you use the solution over and over it can last a whole season – maybe two or three. Mix the KNO3 in water at 1 teaspoon per quart of water and soak the seeds for 4 hours, rinse the seeds well, and plant.

3) Gibberellin Plant Hormone:

I haven’t tried this, though reportedly it will speed the germination of seeds, or even resurrect weak seeds that won’t germinate any other way. It is very expensive, and you run the risk of selecting seeds that will require this treatment in subsequent generations. This should be a last resort method for propagating seeds.

Gibberellin sources are listed in the appendix of “The Pepper Garden” by Dave Dewitt and Paul Bosland.

What you have in your mind?