What Peppers Want
Peppers are not difficult, but they are picky. In this way they are just like my 18 month old son: as long as he’s doing exactly what he wants he’s the most easy-going boy in the world. But stop him from smearing peanut butter on the cat and suddenly he’s screaming like he’s suffering the world’s worst indignities.
Peppers are the same way. Give them the long, hot days and warm nights they want and they’re easy-to-grow. But ask them to put up with a typical cool Maritime climate and they get downright sulky.
Because peppers originated in the tropics, they are not well-adapted to handle wide temperature swings from day to night or over the course of the season. Ideal temperatures for growth and fruiting are about 85 degrees during the day and 70 degrees at night.
70 degrees at night. Let that sit with you for a moment and you will appreciate why peppers can be such a challenge to ripen around Puget Sound. We have years, and last year was one, when overnight lows barely climbed out of the 5os, and then for only a few days and in warm microclimates.
Growers further South, towards the Willamette Valley, will likely have less trouble, but the techniques described here will still probably help get consistent ripe fruit in a cooler year.
Seeds vs. Starts
In the Pacific Northwest, the question is never “should I sow seeds directly in the ground or use a transplant?” You simply must use starts. Seeds, if they germinated at all outdoors (doubtful), would never grow large enough to produce anything before frost killed off the plant. So, the only thing to ask is, who will be raising those starts: you or a professional plant propagator?
Peppers are not plants to try to start on a South-facing windowsill in the maritime Northwest. If you don’t have a relatively well-equipped space to start peppers, don’t bother starting your own. They need strong light and a warm germination space.
(Read more about my indoor seed-starting set up.)
Peppers grow slowly and cannot be rushed outside, so they’ll take up a lot of time and space under your lights and will tend to get quite lanky and weak if kept in front of a window. If you are growing just a few pepper plants, buy strong, locally and professionally-raised transplants at a local nursery (not Home Depot – ever!) and don’t feel bad about it.
(Read more about selecting quality transplants.)
If you’ve got the space, the lights and either heat mats or a warm indoor area to get germination off to a strong start, peppers are grown out just like tomatoes. I start them at the same time, typically in mid-to-late-February. Conventional wisdom is to start peppers a few weeks later than ‘maters, to allow outside temps to warm up a bit more, but I find the slower growth of peppers gives me that margin.
Whether you grow or own or buy transplants, you want short-season, Pacific Northwest adapted varieties. If you’re starting from seed, just make sure you use a seed house that specializes in cool season crops and read the catalog carefully.
If you’re buying starts, bring a Territorial Seed catalog with you to the nursery. I am not kidding about this, and it’s a good idea when you buy tomato starts, too. Not all varieties on offer at your nursery will be the same as what Territorial is selling, but I’ll bet you’ll see a substantial overlap. For readers in other bioregions, take the best, most extensive and informative catalog targeted towards your region when you go shopping for starts.
The closer you can get your growing conditions to that magic 85-at-day/70-at-night formula, the happier your peppers will be. In the Pacific Northwest, that means you need to go all out to raise soil temperatures and incorporate heat sinks around your plants.
If you have a greenhouse, use it. If you don’t, construct an inexpensive low-tunnel over the area where you’ll be growing your peppers. Put your low-tunnel in place several weeks before you transplant out your peppers. This will give the soil time to warm progressively deeper and act as an effective heat sink.
Soil temperature can be further raised by covering the soil with black plastic a few weeks prior to transplanting. Gardeners who are opposed to plastic use can find biodegradable black paper mulches which will serve a similar function. A very dark compost mulch will also help the soil absorb more heat.
A heat sink is something that will absorb heat from the sun during the day and release it slowly over the nighttime hours. Water is a tremendously good heat sink, which is why places near water tend to have more moderate day-to-night temperature swings than places further inland and why Wall-0-Water type products work.
Anything dark and with a lot of mass acts as a good heat sink, too, which is why black asphalt gets really hot in the middle of summer, and why tender or semi-hardy plants grown against south-facing rock or concrete walls are more likely to thrive.
If your goal is to ripen peppers, your best bet is is raise air and soil temperature with a combination of techniques, and incorporate heat sinks to ensure overnight temps stay high too. The only risk with heat-bumping techniques like tunnel cloching, plastic mulching and Wall-o-Water products is the possibility of overheating.
Sadly, season extension techniques aren’t a set-it-and-forget-it proposition. You need to carefully monitor the temperatures inside your cloches, particularly on bright days when temps can climp rapidly. Sudden jumps to 90 or more will likely cause blossom or fruit drop of your pepper plants. Also, the warm, humid environment that can build up inside a low tunnel or greenhouse will create ideal conditions for assorted pests, diseases, mildews and molds. Ick.
My experience is that 4 or 6 ripe, full-sized, bell-type peppers off a single pepper plant is a dang good yield. Typical yield for me is maybe 3 ripe peppers and another 3 or 4 green or partially ripened but full sized peppers. Small-fruited peppers are like cherry tomatoes and will give you many more and will tend to ripen more quickly than the full-size versions. Like tomatoes, dates to maturity, flavor, and plant precociousness will vary greatly.
Putting It Into Practice
This is more-or-less what I do. You should adjust exact dates based on your particular microclimate and willingness to fuss over your plants. Some years everything goes a lot faster. Some years, slower. I use peppers that claim a 60 or 70 day to maturity but really, it’s 6 or 7 months from seed to ripe pepper. In seed catalogs, dates to maturity of peppers are typically the time from date of transplant to date of edible green fruit, which always seems a bit deceptive to me.
- Late February – Start peppers indoors in 4″ pots.
- Mid-April – Up pot peppers to gallon pots. Make sure final grow out space is prepared with soaker hose, black plastic mulch and buttoned-up low tunnel if not growing peppers in greenhouse.
- Early to mid-May – Begin hardening peppers off in the greenhouse. Covering the plants with floating Reemay inside the greenhouse further protects them, but at this point I will still shuffle pots inside and outside depending on temperatures.
- Late May to early June – transplant peppers to final location (note: for me this is almost always the greenhouse.)
- June – flowering and fruiting starts
- Mid-July – substantial green fruit set
- Mid-August – peppers at full size
- Early to mid-September – peppers fully ripe and harvestable.
- Early to mid-October – even with protections, plants start to fall apart as temperatures drop rapidly.
That’s how I get peppers in the Pacific Northwest. It may not be worth it for every gardener, but it’s a fun challenge if you’re into that kind of thing. What do you do?