Must-Have Indoor Seed Starting Supplies

Nurturing your own seedlings adds to the enjoyment of being a gardener. Plus:

• Depending on your climate, you can get a jump-start on planting. Bragging rights for the first ripe tomato are at stake.
• Seeds are more budget-friendly than purchasing seedlings. For the cost of one good-sized seedling, you can buy several packets of seeds that can produce tens of seedlings.
• Unlike seedlings at the plant nursery, you have access to unusual, rare and heirloom varieties when you start with seeds.
• Planting your own seeds gives you more control over the types of fertilizer, soil and pest control involved.

To go from seed to seedling successfully, you'll need these essentials: a suitable indoor location, soil, seeds, pots or trays, grow lights, misters, seed starter kits and planting tools.

Growing healthy seedlings starts with a dedicated space where you can regulate air temperature and light. If possible, choose an area with natural light and good airflow. You can set up shelves or use a work table. If you're starting small with a seed starter kit, a kitchen table works well. Seeds thrive in warmth, with an ideal soil temp of between 65 and 75 degrees Fahrenheit for germination.

Consistency is the key because if your plants get too hot or too cold they can stop growing or die. A gardening heat mat can prove to be a worthwhile investment.

Before you take your pick of an almost endless variety of vegetable, flower and plant seeds, do a little research. Not all varieties of plants can grow everywhere successfully. Consider using a seed starting chart to determine the best times to plant based on last frost in spring and first frost in fall.

Most seeds have maps on the back of their packages that tell you which climate areas work best for them. It will also indicate the ideal time for transplanting your new seedlings to an outdoor garden bed or container. Usually, you’ll plant 6 to 8 weeks before the final frost in your area.

Below are some types of seed that make good starter seeds:

• Organic seeds require a higher upfront investment but you get the peace of mind of knowing they don't contain pesticides or other ingredients. (All the seeds at The Home Depot are non-GMO.)
• Heirloom seeds have remained virtually unchanged for generations and adapt to different climates.
• Hybrid seeds offer benefits such as a higher yield, better flavor and disease resistance.
• Pelleted seeds are coated with graphite or clay that makes tiny seeds easier to sow.

You can grow your seeds in pots made of plastic, clay or biodegradable materials like peat. Choosing the right seed trays or pots will depend on your seeds, budget and preference.

• Plastic is budget-friendly and lightweight.
• Clay drains well but can break.
• Peat is biodegradable and breaks down quickly.

If this is your first time sowing seeds indoors, starting with a kit is a good investment. You'll have everything you need in the kit to start your own seeds. Begin by hydrating the peat pellets with warm water, then create small indentations in the soil plugs and plant two seeds per cell, covering the kit to retain warmth and moisture. After you sow the seeds, follow package directions for watering care, hardening off and transplanting into your garden.

If you’re using the winter sowing method, you can use recyclable plastic containers such as soda bottles, yogurt cartons or milk jugs. Winter sowing lets you use outdoor weather changes to encourage seeds to germinate. The best times for winter sowing are January through March, depending on the climate where you live.

Tips for winter sowing seeds:

• Punch a few drain holes in the bottom of your recycled containers.
• Add potting soil, seeds and water.
• Turn the container into a "mini greenhouse" by sealing it with duct tape.
• Put your mini greenhouse outside in a sunny spot.
• Check regularly to make sure the soil remains moist and the seedlings are thriving.

Regular garden soil is dense and lacks essential nutrients, making it unsuitable for seed planting. A better solution is potting soil formulated specifically to grow healthy roots. This type potting mix is packaged as "seed starting soil." You can create your own by combining equal parts building sand or perlite and compost with twice as much peat moss. Sift the mixture to add air. This will make it easier for your seeds to grow.

Alternatively, you can skip seed trays altogether and make your own seed blocks. With the seed blocking method, you sow your seeds directly into densely packed soil without a pot. When your seedling is ready, you can plant it without disturbing its roots.

How to use a soil blocker:

• Mix potting soil with enough water to hold its shape when squeezed.
• Using a soil block maker, compress your mix into blocks.
• Place your blocks on a plastic tray and sow your seeds.
• Lightly mist the soil often to keep it moist.

Consistent, ample light makes all the difference when growing seedlings. Some varieties can require 12 to 16 hours of bright light each day. Natural light isn’t always available, so invest in grow lights. These LED or fluorescent lights are made specifically to give plants the exact type of light they need. Choose grow lights with full-spectrum bulbs and position them about 2 to 3 inches above your plants. Consider using grow lights that you can raise or lower as your seedlings grow.

Different seeds require differing amounts of light to germinate. Best advice is to read seed packets and online information for the seeds you're growing.

Tip: When using natural light, make sure to rotate your seedlings at least twice a week so they grow straight.

Seeds and seedlings require precise amounts of water and humidity as they grow. Too much water rots seeds or roots and causes mold and fungus growth. Underwatering weakens plants, leaving them susceptible to pests and diseases. The tools and techniques below will help you water and maintain your seedlings correctly:

• Use humidity dome covers to keep soil warm and moist so seeds germinate.
• Get a mister or spray bottle with a fine nozzle. This will keep the soil moist without disturbing the seeds or seedlings.
• Maintain humidity levels of 40 to 60 percent in your growing area with a humidifier.

Tip: Check seedlings daily to make sure they're getting the light and water that they need. Once problems like mold start, they're difficult to eradicate.

Starting seeds is an exciting project, but can come with pest and disease challenges.

Protect your starter seedlings from insect pests like aphids, spider mites, thrips and fungus gnats. Check them often for signs of problems. Once your seedlings have true leaves, you can start using organic liquid fertilizers designed for seed starting. Start with half the recommended dose and always feed from the bottom tray.

• White powder on leaves can be aphids. Use natural fungicides like neem oil to get rid of them.
• Silver streaks on leaves are often thrips. Use insecticidal soap on infected leaves.
• Webbing means spider mites. Mist the leaves or use neem oil or a pesticide.
• Gnats are hard to miss. Sticky traps are a good solution.

Many beginning gardeners become discouraged by "damping-off." This term refers to a group of diseases caused by tiny organisms in the soil that stop seeds from sprouting or harm young seedlings just as they’re starting to grow.

Damping-off happens in two ways:

• Before seeds sprout (pre-emergence): Sometimes, seeds never make it to the surface because they rot in the soil before they can sprout.
• After sprouting (post-emergence): In other cases, seedlings pop up and then suddenly collapse. This happens when the stems near the soil become soft and weak, often turning brown or black, causing the tiny plants to fall over.

While damping-off disease can be frustrating, understanding it is the first step to preventing it and giving your seedlings the best chance to thrive.

Experts recommend prevention as the only effective way to manage damping off. Once you spot it, you can't eradicate it.

The pathogens that cause damping-off disease survive in contaminated soil and on dirty tools and containers. Follow these practices to reduce damping-off disease in your seed-starting projects:

• Use packaged, sterile soilless potting mix. Never use soil from your garden.
• Sterilize tools and containers in a diluted 10 percent bleach solution and rinse thoroughly before using.
• Keep your work areas and surfaces clean and avoid placing containers and seed starting mix on dirty floors.
• Don't overwater seedlings. Allow the surface to slightly dry between waterings.
• Water from the bottom of the tray or lightly mist seedlings.
• Using heat mats speeds up germination and gets seedlings past damping-off danger sooner.
• Use a fan to increase air circulation to reduce humidity.
• Some seed varieties are resistant to damping-off disease. Check packages for more info.

When your seedlings are ready, follow these guidelines for planting in your garden:

• The right soil temperature is key to successfully transplanting seedlings into your garden. For cool-season crops like broccoli, cabbage and lettuce, the soil should be at least 50 degrees Fahrenheit.
• Warm-season crops like tomatoes and peppers need a minimum soil temperature of 60 degrees Fahrenheit, with 65 to 70 degrees preferred for strong root growth.
• Use a soil thermometer to measure soil temperature.

Seed starting experts recommend hardening off seedlings over a two-week period to acclimate your new plants to the outdoors. This is especially important in early spring when temperatures can fluctuate widely.

When you gradually expose seedlings to the elements, you strengthen their defenses, minimize transplant shock and boost their chances of thriving in the garden.

Steps for hardening off seedlings:

• Start gradual exposure (days 1 to 7): Place seedlings in a sheltered outdoor spot for a couple hours on the first day, increasing exposure time daily while protecting them from direct sun and wind.
• Introduce environmental stress: Reduce watering slightly, stop fertilizing and gradually expose seedlings to morning sunlight, avoiding harsh midday heat.
• Full acclimation (final days): Leave seedlings outside all day and night (if frost-free), ensuring they can handle full sun and outdoor conditions before transplanting.

Once your seedlings are acclimated, follow these tips for transplanting into your garden:

• Gently handle seedlings and try not to touch the stems and roots.
• Dig a hole slightly larger than the root ball.
• Lightly water and press down the soil around the base of the plants.
• Clearly label your seeds and use the same marker in your garden.

Look for trowels designed for transplanting tender seedlings. They're narrower than standard garden trowels and usually angled to support the plants.