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Successfully start those peppers from seed |
Jessica Walliser, Columnist

Successfully start those peppers from seed

Jessica Walliser
| Friday, January 4, 2019 12:00 a.m
Jessica Walliser
Pepper seedlings require supplemental light to perform their best.

Question: I’m interested in growing some unusual peppers this season that I can’t get as transplants at the nursery. I’ll need to start my own seeds. I know peppers can take longer to grow from seed than other vegetables, so I’m looking for some tips to get started.

Answer: Starting your own pepper seeds can prove challenging. They have slightly different care requirements than other, easier-to-start seeds such as tomatoes or marigolds. They take longer to germinate and require a lot of heat and light to get off to a good start. Regardless of whether you’re growing hot or sweet peppers, this advice should help.

Begin by getting the timing right. Unlike some other flower and vegetable varieties whose seeds germinate just a few days after planting, peppers take two or three weeks to germinate. Because of this, you’ll want to start them a bit earlier than other garden plants. Start sowing pepper seeds about 10 to 12 weeks before the last expected spring frost. Here in Western Pennsylvania, that means late February. This timing gives the plants two to three weeks to germinate, followed by a good two months to grow before moving them outdoors.

You don’t need a special grow light to start peppers from seed, but you should have a supplemental light source of some kind. While a sunny windowsill is fine for most other garden seeds, pepper seeds grow much better with a closer, more intense source of light. If you don’t have grow lights, buy a few inexpensive shop lights with fluorescent tubes and hang them from the ceiling on adjustable chains. Raise and lower the shop lights so the bulbs are constantly 2 to 3 inches above the plant tops. Leave the lights on for 18 to 20 hours per day.

Pepper seedlings are prone to developing fungal issues such as damping off and botrytis, which they can easily pick up from old potting equipment. When starting pepper seeds, always use clean, sterile containers. I use a 10 percent bleach solution (9 parts water to 1 part bleach) to kill any pathogens clinging to my seeding flats and nursery trays before using them to grow new seeds each season.

Select a high-quality, sterile potting soil formulated specifically for seed starting to grow your pepper seedlings. Do not reuse seed-starting potting soil.

For pepper seeds, warmer soil temperatures mean better germination. One of the most critical tips for starting pepper seeds is heat. A seedling heat mat will cost you $20 to $30 and can make the difference between success and failure. These flat, waterproof, electric mats are placed under the containers or trays and raise the soil temperature about 10 to 15 degrees above room temperature. Use the mat until the seedlings have developed their first true leaves, then remove it.

Pepper seeds should be planted about 14 to 12 of an inch below the soil surface. Seeds that are planted too deeply may not sprout, while those planted too shallowly may dry out before they germinate.

After covering the seeds with a light layer of soil and watering them in, place a piece of clear plastic over the tray. Plastic wrap from the kitchen will do just fine. This creates a mini greenhouse over the seed trays, raising the humidity and keeping the soil constantly moist. Remove it only when you need to water. But, as soon as the first few seedlings begin to sprout, remove it permanently, otherwise you could promote fungal diseases.

Check your seedlings every day and feel the soil to see if it’s time to water. When you do water, make sure at least 20 percent of the water you pour onto the top drains out the drainage holes in the bottom of the flat. This flushes out excess fertilizer salts.

When the seedlings develop their first true leaves, it’s time to start feeding your pepper seedlings. Every two weeks, use a liquid organic fertilizer diluted to half the recommended strength on the bottle.

As your pepper seedlings grow, they’ll need good air circulation to both avoid fungal diseases and strengthen their stems. Set an oscillating fan on a timer and have it run for two hours in the morning and two hours in the evening. It should blow across the tops of the seedlings, causing them to wiggle a little as it passes.

When your seedlings have developed two or three sets of leaves, it’s time to separate your babies and transplant them into larger containers. Use sterile potting soil again, but this time you can choose one not specifically formulated for seed starting.

Once outdoor planting time arrives, harden off your seedlings by gradually acclimating them to outdoor conditions. About three weeks before planting them out, move the seedlings to a shady area outdoors for a few hours every day. Do this for several weeks, gradually exposing them to more sunlight and wind as well. This gradual adjustment to outdoor conditions helps the plants deal better with the move.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug” and her newest title “Container Gardening Complete.”
Her website is
Send your gardening or landscaping questions to or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is Send your gardening or landscaping questions to or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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