How to Start a Fall Garden Indoors Under LED Grow Lights

How to Start a Fall Garden Indoors Under LED Grow Lights

As the cooler months approach, gardeners often turn their attention to starting a fall garden. Beginning your seedlings indoors under LED grow lights is an excellent way to extend your growing season and ensure that your plants are robust and healthy when it's time to move them outdoors. This guide will walk you through the essential steps for starting a fall garden indoors, with practical tips and product recommendations to help you succeed.

Select the Right Plants

Choosing the right plants for your fall garden is the first step. Hardy vegetables such as kale, spinach, carrots, beets, broccoli, radishes, peas, Swiss chard, lettuce and garlic are ideal for fall planting. These crops thrive in cooler temperatures and can be started indoors before being transplanted outdoors.

Active grow how to start a fall garden under led grow lights lettuce.

For a more detailed list of recommended plants and their specific growing needs, be sure to check out our blog post: "Top 10 Plants to Start in Early Fall". This guide provides in-depth information on each plant, including their DLI requirements and other important growing tips.

Setting Up Your Indoor Grow Space

Creating the perfect indoor environment is crucial for the successful germination and growth of your seedlings. Here are some key components to consider:

LED Grow Lighting

Seedlings need plenty of light to develop strong roots and stems. For gardeners working with racking systems, Active Grow Integrated Strip T5 LED Grow Lights are an excellent choice. Two 4' T5 units can cover an 18"x4' shelf, providing ample light for your seedlings.

If you have a smaller setup, the Active Grow Integrated Dual T8 LED Grow Light is a great option, with one to two units per shelf being sufficient.

For those looking to grow their plants even larger indoors before moving them outdoors, we offer a higher output solution: the Active Grow T5 HO 2.0 4FT LED Grow Light which includes 4xT5 HO 4FT LED Grow Lamps. This setup provides increased light intensity, allowing your plants to develop more robustly indoors. One fixture can effectively cover each 18"x4' shelf, making it ideal for gardeners who want to maximize their indoor growing potential.

Temperature & Humidity

Consistent temperature and humidity levels are essential for healthy seedling growth. The Active Grow 3-Tier Walden Grow Tent is perfect for creating a controlled environment. The tent not only improves light uniformity but also helps maintain the necessary temperature and humidity levels, all while being energy-efficient.

Inside the tent, use our 1020 heavy-duty trays, along with seed starting trays and humidity domes to create the ideal conditions for your seedlings.

Active grow how to grow better pbar dli illustration.
Mastering Daily Light Integral (DLI)

Daily Light Integral (DLI) refers to the total amount of light a plant receives each day. Understanding your plants' DLI requirements is key to their growth. For example:

Kale & Spinach:
Seedling: 6-10 mol/m²/d
Vegetative to Maturity: 12-20 mol/m²/d

Carrots & Radishes:
Seedling: 4-8 mol/m²/d
Vegetative to Maturity: 10-20 mol/m²/d

If you're unsure about your plant’s exact DLI needs, our DLI Calculator is a valuable tool to help you optimize your lighting setup, ensuring the best possible growth outcomes.

Growing Setup & Lighting Considerations

The growing setup you choose—whether an open racking system or our 3-Tier Walden Grow Tent—will influence the uniformity and average Photosynthetic Photon Flux Density (PPFD) your plants receive. Using an open rack system offers flexibility, but the light distribution may be less uniform. In contrast, our 3-Tier Walden Grow Tent can significantly increase both light uniformity and average PPFD, ensuring that your plants receive consistent and effective light exposure.

To meet your plants' specific DLI requirements, you can select the appropriate lighting solution based on your setup. Our T5 HO 2.0 LED Grow Light offers a higher output, making it ideal for growers who want to maximize their indoor growing potential before transplanting outdoors. The Integrated T5 and T8 LED Grow Lights are also excellent options, with the ability to adjust PPFD by raising or lowering the fixtures to fine-tune light coverage and intensity.

Provide Ample Light Duration

Seedlings are particularly light-hungry and require long durations of bright light to sprout successfully and develop vigorously. Without enough light, seedlings can become weak and stretched, often leading to them toppling over and failing to thrive.

Active grow how to start a fall garden under led grow lights integrated t5 4ft 4 lamp.
Active grow how to start a fall garden under led grow lights timer.

To avoid this, use a light timer to keep your grow lamps on for an average of 16 hours per day for young seedlings. If your grow area is near a bright window, you can reduce this to about 14 hours. In spaces with less natural light, consider extending the duration to up to 18 hours per day. Monitor your seedlings closely to see how they respond and adjust as needed.

Another advantage of using LED grow lighting like our Integrated LED Grow Lights, is that they generate minimal heat, allowing you to place them closer to your seedlings (as close as 3" to 6") without the risk of burning the young plants. This proximity ensures high light levels essential for strong, healthy growth.

Active grow how to start a fall garden under led grow lights low heat.
Active grow how to start a fall garden under led grow lights hardening off.
Timing Your Seedling Start

Starting your seeds 6-8 weeks before your area's average first frost date gives your plants enough time to establish strong roots and foliage indoors. Once your seedlings are ready, they can be gradually acclimatized to outdoor conditions—a process known as "hardening off." This involves exposing your seedlings to outdoor conditions for a few hours each day, gradually increasing the time over 7-10 days.

Transplanting Seedlings Outdoors

When your seedlings are strong and the outdoor conditions are suitable, it’s time to transplant them into your garden. Ensure your garden bed is well-prepared with nutrient-rich, well-draining soil. Transplant carefully, keeping the root ball intact, and water the plants thoroughly after planting.

Pro Tip: To streamline the transplanting process, use our heavy-duty trays to organize and transport your seedlings. These trays minimize the risk of damaging your plants during the move.

Active grow how to start a fall garden under led grow lights transplanting.
Active grow how to start a fall garden under led grow lights watering seedlings.
Additional Tips for Success

Watering: Keep the soil evenly moist, but avoid overwatering. Use a spray bottle or a gentle watering can for best results.

Fertilizing: Once your seedlings have their first true leaves, begin feeding them with a balanced, water-soluble fertilizer to support continued growth.

Pest Management: Even indoors, pests like aphids and fungus gnats can pose a threat. Regularly inspect your plants and use natural pest control methods if needed.

Starting a fall garden indoors under LED grow lights allows you to extend your growing season and ensure your plants are well-prepared for outdoor conditions. By carefully selecting your plants, setting up an optimal indoor environment, and using the right tools and equipment—such as our Integrated T5 and T8 LED Grow Lights, T5 HO 2.0 LED Grow Light, 3-Tier Walden Grow Tent, 1020 heavy-duty trays and humidity domes—you can enjoy a bountiful harvest even as the days grow shorter.

Happy growing!