Seed Starting Guide for the New Year
How to Start Seeds Indoors: Your Guide to Start Growing in 2025
The cold, quiet months of winter offer a perfect opportunity to kickstart your garden by starting seeds indoors. It’s not just a practical way to save money; it’s a deeply satisfying ritual that reconnects you with the soil. Whether you’re dreaming of sun-ripened tomatoes, fragrant sweet pea flowers, or the beautiful blooms of zinnias, starting seeds indoors sets the stage for a thriving garden. Here’s everything you need to know to get started.
Step 1: Read Your Seed Packets Like a Pro
Seed packets are treasure troves of information, offering guidance on planting depth, spacing, days to germination, and special needs. For instance, some seeds need a 12-week head start indoors, while others are ready just three weeks before transplanting outdoors. Pay attention to whether seeds require light or darkness to germinate and organize them by their starting times relative to your region’s last frost date.
Pro Tip: Store seed packets in an airtight container, away from sunlight and moisture, at a steady temperature of 65° to 75°F until you're ready to plant.
Step 2: Pinpoint Your Last Frost Date
Your region’s average last frost date is the foundation of your seed-starting schedule. This date tells you when it’s safe to move your seedlings outdoors and begin direct sowing.
Use tools like NOAA’s database or gardening websites to find your frost date by entering your zip code. Mark this date on your calendar and count backward to plan when to start your seeds. For example, if your last frost date is April 20th and your tomatoes need to be started eight weeks prior, plan to sow them indoors around February 23rd.
Step 3: Use the Right Seed Starting Mix
Skip the garden soil and opt for a sterile, finely textured, soil-less seed-starting mix. This mix promotes root development and prevents fungal diseases like damping off. Pre-moisten the mix with room-temperature water before filling your seed trays or pots.
Sterilize your containers—especially if they’ve been used before—and ensure they have good drainage. After planting, water gently with a spray bottle, tamp the soil lightly, and label each variety to avoid confusion.
Step 4: Perfect Your Watering Routine
Consistency is key when watering seeds. Keep the soil evenly moist but not waterlogged, especially during germination. Cover seed trays with clear plastic to retain moisture, but remove the cover as soon as sprouts appear. Allow the soil surface to dry slightly between waterings to prevent disease.
Bottom watering is another great method: place seed trays in a shallow water-filled tray, allowing the mix to absorb moisture from below. Always drain excess water to avoid oversaturation.
Step 5: Provide Optimal Light and Warmth
Seeds germinate best in soil temperatures between 65° and 75°F. Use seed heat mats if your space is chilly. Once seedlings appear, move them to a cooler area (60° to 65°F) with good air circulation. A small fan can help strengthen seedlings and prevent fungal issues.
Forget the windowsill—it simply doesn’t provide enough light. Invest in grow lights and hang them just an inch or two above the seedlings, adjusting as they grow. Most seedlings need 16 hours of light daily, while warmth-loving plants like tomatoes thrive under continuous light until they’re well-established.
Seedlings stretching for light. Ensuring proper light (whether sun or articifical) will help prevent stretching which tends to make seedlings long.
Step 6: Feed and Handle Seedlings with Care
Once your seedlings develop their first true leaves, start feeding them weekly with a half-strength liquid fertilizer. Thin out weaker seedlings to avoid overcrowding, but handle the process gently. If space allows, transplant thinned seedlings into separate pots.
When your seedlings outgrow their containers but aren’t ready for the outdoors, pot them up into slightly larger containers. This ensures they have enough room to grow strong roots until transplant time.
Step 7: Gradually Transition Seedlings Outdoors
Sudden exposure to outdoor conditions can shock young plants. Begin hardening off your seedlings 7–10 days before transplanting by placing them outside for a few hours each day in a sheltered spot. Gradually increase their outdoor time, bringing them in each night.
On transplant day, choose a calm, overcast day to reduce stress. Even if the weather seems warm, don’t plant before your last frost date. Your patience will be rewarded with robust, thriving plants.
Starting seeds indoors is more than a gardening chore; it’s a hopeful act of creation. With these tips in hand, you’ll set the stage for a garden that nourishes your body and soul. Whether you’re growing for beauty, flavor, or both, there’s nothing quite like watching life sprout from the tiniest seeds—all thanks to your care and intention.
Seed Company Picks for 2025
A premium selection of organic, non-GMO, open-pollinated and heirloom herb seeds to enhance your culinary creations, herbal remedies, and garden aesthetics. I particularly love the ethos of this brand and always appreciate supporting a family owned company.
Bucktown Homegrown Wellness Seed Pack
Bucktown offers a delightful variety of cut flower seeds, but what truly sets them apart are their thoughtfully curated seed kits. These kits are ideal for smaller garden spaces, allowing you to create a cohesive, themed display. My personal favorite is the Homegrown Wellness Seed Pack with Holy Basil, Sage, Calendula, Chamomile, Echinacea and Lemon Balm.
Mountain Rose Herbs, based in Eugene, Oregon, is an exceptional provider of organic herbs, spices, teas, and essential oils, all sourced with a commitment to sustainability. I love their dedication to quality and ethical sourcing—it aligns with my values of supporting the earth while offering exceptional ingredients for both wellness and creativity in my work.
High Mowing Organic Seeds, based in Wolcott, Vermont, is a leading provider of 100% organic, non-GMO seeds, offering over 600 varieties in its catalog. As a long-time customer, I appreciate their exceptional assortment of organic heirloom seeds, which have consistently yielded robust and beautiful harvests in my garden.
Botanical Interests, founded in 1995, provides an impressive variety of non-GMO and organic seeds, with each packet featuring detailed instructions and artwork designed to inspire gardeners. Having relied on them for years, I admire their dedication to quality and the beauty of their seed packets, which also make thoughtful and unique gifts.