The hardest seeds to start indoors need special conditions or very long growing times. Peppers, celery, and lisianthus top this list of difficult seeds to germinate for most home gardeners. Each one demands extra care that basic crops like tomatoes and basil do not need from you at all.
I failed at lisianthus twice before I figured out what I was doing wrong in my basement setup at home. These flowers need 16 to 17 weeks of indoor growing before you can transplant them outside. That means starting them in December or early January for a May planting date in most zones across the country.
In my experience, peppers frustrate more beginners than any other crop you can try to grow from seed. They need soil warmth of 80°F (27°C) just to sprout within two weeks of planting. Cold soil means your seeds sit for a month or never come up at all from the trays you planted them in at home.
Celery surprises gardeners with how long it takes to grow from seed to transplant size each spring season. You need 10 to 12 weeks of indoor time for plants big enough to handle outdoor conditions in your garden beds. Start too late and your celery never sizes up before hot weather ruins the flavor and texture of your stalks.
Lavender and other perennial herbs need cold treatment before they will sprout for you at all from the soil. This process called stratification means putting your seeds in the fridge for 4 to 6 weeks before planting them in soil. Skip this step and you will wait forever for plants that never come up from the soil at all.
UMN Extension data shows the huge range in seed timing that catches new gardeners off guard. Zinnias take just 3 weeks from seed to transplant while lisianthus takes a full 17 weeks. These challenging seeds for beginners need careful planning. You must start months before you want your flowers or vegetables ready to plant in your garden beds.
Buy a heat mat if you want to grow peppers or eggplant without constant worry each spring season at home. Mark your calendar for slow starters like celery and lisianthus months ahead of when you plan your other seeds. Research each plant before you order so you know what you are getting into with all your seed choices for the year ahead.
Read the full article: When to Start Seeds Indoors: Ultimate Guide
