Starting seeds now for the garden is tempting. Racks of seed packets with their pretty images of fresh vegetables and cut flowers are like heart-shaped boxes of chocolate. Each packet is a morsel, a promise of something good to come. Starting seeds is like eating chocolate, who can resist?
As with chocolate, however, some restraint is needed. February feels like it is time to sow seeds. Surely a garden center full of seed packets is sending us a message. But before you start, here are a few tips on when to start which particular plant. This is a two-part article: this article will explain the difference between cool and warm season plants and when to start warm season plants. The subsequent article will cover cool season plants.
Learn which plants prefer warm versus cool weather
The first step is to make a list of what you want to grow and/or your seed packets. From that list, identify which plants prefer cool or warm temperatures.
For example, if you wish to start seeds of tomatoes and cilantro, mark tomatoes as a warm season plant. Plant tomatoes outside when there is no danger of frost. Cilantro prefers cool weather and can tolerate a light frost.
If you don’t know, ask your local extension agent, look online at seed catalogs, or read a printed seed catalog or a gardening book. A few online seed catalogs that provide quality descriptions for this are Burpee, Johnny’s Selected Seed, Botanical Interests, Southern Exposure Seed Exchange, and Renee’s Garden. Just type in the plant name in their search bar and don’t worry so much about the cultivar for now.
Learn your average last frost date
Focusing on the warm season plants for now, identify your average last frost date. Using davesgarden.com and my zip code, my risk of frost in my Northern Virginia zone 7 garden, is from October 13 through April 23. I am almost guaranteed not to get frost from May 9 through September 29. I arbitrarily picked April 30 as the day when I can move my transplants from inside to outside to harden off. Picking the end of a month makes it easy to remember and to calculate weeks.
Using April 30 as the marker, count back the number of weeks it takes for that seed to germinate and reach transplanting size. This information should be on the seed packet but if not go back to the original resources I listed above. My tomato seed packages say “start seeds 6 to 8 weeks before average last frost” or “before transplanting.” Keep in mind that this is only to get a jump on the season. You can always start seed outdoors after the danger of frost has past but quite a few weeks of growing season would be lost. Six weeks from April 30 is mid-March, which is when I would sow my tomato seeds in small containers under lights.
Purchase lights to starting warm weather seeds indoors
Starting seed by a window does not provide enough light. The seed container has to be just a few inches under the florescent tubes or special grow lights. Therefore if you are interested in growing from seed, invest in lights but you can use cheap fluorescent tubes from hardware stores. Once you turn on the lights, you keep them on for 14 to 16 hours every day until you move the plants outside.
Decide which seeds to start under lights
Your indoor light system becomes prime real estate. Within the category of warm season plants, identify which seeds should be started indoors in this prime real estate section, i.e., need a head start before the end of April. Separate that list from those that could be started outdoors in the beginning of May. For example, because beans germinate and grow quickly to produce a harvest, start them outdoors in May and save the prime real estate for tomatoes that need a month and a half head start. Identify the number of weeks recommended for starting seeds indoors for each plant. Usually one starts tomatoes, peppers, eggplants, broccoli, cabbage, cauliflower, collards, onions, celery, and Brussels sprouts indoors to get a jump on the season. Start beans, corn, watermelons, zinnias, sunflowers, summer squash, cucumbers, pumpkin, and basil outdoors in May.
This is an example of what my list looks like for starting seeds of warm season plants under lights. I will try several varieties of pepper, tomatoes, and melons, which takes up even more space under the lights.
March 1: Eight weeks prior to average last frost date of April 30
- Chas C. Hart Seed giant pascal celery
- Chas C. Hart Seed outhouse hollyhocks single mixed colors
- Burpee Confetti hybrid pepper
- Burpee Jungle Parrot pepper
- Southern Exposure Seed Exchange Jimmy Nardello’s Italian sweet pepper
- Southern Exposure Seed Exchange Feherozon bell pepper
- Lake Valley Seeds Sweet Marconi red pepper
March 15: Six weeks prior to average last frost day of April 30
- Burpee Atlas Hybrid tomato
- Burpee Shimmer Hybrid tomato
- Southern Exposure Seed Exchange Glacier tomato
- Renee’s Garden Litt’l Bites cherry tomato
- Southern Exposure Seed Exchange Thai red roselle
April 15: Two weeks prior to average last frost date of April 30