Gardening Sweet Spots
By Donna Hessel
Seeds That Grow Well Under Lights
Veggie and herb seeds that sprout readily under grow lights include basil, tomatoes, peppers, spinach, cucumbers, lettuce, cilantro and broccoli. Try flower seeds like zinnias, cosmos, celosia, marigold, calendula, nasturtium, sunflowers, coleus, morning glories and strawflower. Annuals that don’t need stratification (a period of cold prior to planting) will be easiest to start under lights.
Constructing a Grow Light System
Grow light systems are available to purchase ready-made, but building one is relatively easy. A shelving system is the basic ingredient.
A wire shelving unit will work well because lights can be attached to the wire frame. A unit with movable shelves will facilitate raising or lowering plant trays rather than the lights during the growing cycle. After the unit is assembled, it should be placed on a rubber mat or shallow plastic tray to protect the floor. The next step is to attach the grow lights that have been selected. They should be approximately the same width as the shelving unit and there should be one fixture for each section.
Most grow lights come with wire to hang them. Wires can be attached to an S-hook to hang above the plants. When starting seeds, the trays need to be closer to the lights. As plants grow, they can be farther from the lights. Using a link chain to hang the lights will make raising or lowering them easier. The lights need to be on for 12 to 16 hours a day, so plugging them into a power strip with a timer will maintain the schedule required. The power strip can be attached to the unit with zip ties.
Purchasing Grow Lights
The grow light system will require T5 Bulbs, which are affordable, lightweight and effective. They are available in both LED and fluorescent varieties. LED lights are recommended for several reasons:
- LED lights produce less heat
- LED lights are less expensive over the long run because they last longer
- LED lights offer the color spectrum needed
- LED lights use up to 50% less energy and are consequently more efficient
What does the T5 designation mean? The T refers to tubular and the 5 refers to the diameter (5/8”). A T5 light is a tubular light that is 5/8ths of an inch in diameter. The lights come in 2- 3- and 4-foot lengths and should be approximately the width of the shelves. T5 lights are also available as fluorescents, but may be harder to find due to the trending popularity of LEDs.
Selecting the Correct Color Spectrum
The two most critical spectrums for growing plants are red and blue light. The red spectrum light stimulates growth and flowering, but too much red light leads to tall, weak plants. The blue spectrum light regulates the proper amount and distribution of plant growth, assuring that all parts of the plant become the proper size, shape and density. The color of the light created by each type of bulb is determined by its interior phosphor coating. Using an alternating combination of the red and blue spectrum lights in a fixture would provide the best growing situation, mimicking nearly the entire color spectrum of the sun. However, since the seedlings will be planted outdoors prior to flowering, a cool white T5 light in a range between 5000K and 6000K is ideal.
The bulbs don’t look red or blue. They may be labeled “cool white” or “warm white.” Cool white bulbs offer yellow, green and blue spectrum lights for plants. They have a Kelvin range between 5000 -6000K. Warm white lights provide orange and red spectrum light. Warm white bulbs have a Kelvin range between 2700 – 3500K.
The lights need to be placed 2”-3” above the trays when seeds are first planted. Lights should be raised as seedlings grow, to an ultimate height of about 16”-18” when seedlings are ready to be moved outdoors. If leaves look crispy or burned, the lights are too low. If the plants appear thin and leggy, the lights are too high.
Getting Started with Planting
Seeds can be started in almost any type of container that is at least two to three inches deep and has drainage holes. Purchased trays that are made for seed starting are easy to fill with growth medium, convenient to move and have the proper drainage in place underneath. A self-watering tray makes watering easy and may be an investment to consider.
Seeds need to be planted in a growing medium mix that is made for germinating seeds (such as ProMix). Soil from the garden or potting soil is too dense. A fresh, sterile mix ensures healthy, disease-free seedlings. The planting mix needs to be moistened to a crumbly but not gloppy state. The containers should be filled firmly with the moistened mix. Most growing mediums do not contain fertilizer (check the label to be sure), so seedlings need to be fertilized with a liquid fertilizer after they germinate until they are planted in the garden.
Planting, Watering, Fertilizing
The seed packets will list the depth that each type of seed should be planted. Some seeds require light to germinate and should be sprinkled on the soil surface. Others may require planting 1/8” to 1” deep. More than one seed can be planted per cell, but after they sprout only one should be left to grow. Planted seeds can be moistened with a mister or small watering can. A dome made from plastic wrap to fit over the seed starting tray will keep seeds moist before they germinate. It should be removed after germination to allow air to circulate.
Seedlings should be kept moist but not soggy and soil should dry slightly between waterings. Containers with holes on the bottom can be set in a tray of water. Bottom watering is an effective way to keep newly formed roots moist without getting upper leaves wet, reducing the risk of rot. After the second set of leaves form, seedlings should receive a regular dose of organic liquid fertilizer.
A heat mat is an accessory worth considering, especially when starting tomatoes, peppers and other summer nightshade veggies indoors. Commercial heat mats keep the soil about 10 degrees warmer than room temperature, perfect for growing in a cool garage or basement. Some come with a thermostat that can be set to a specific temperature for maximum success with specific plants. Heat mats should be removed as soon as plants germinate and need cooler temperatures.
Prepping Seedlings for the Outdoor Garden
The seedlings need a gradual transition to the outdoor garden. They are ready to move outdoors when there is a good netting of white roots and spring temperatures are consistent. Readying seedlings for planting outdoors is called “hardening off.” Containers need to be moved outdoors to a protected place that is lightly shaded and out of the wind about a week to 10 days before planting in the garden. After a few hours, they can be brought back indoors. Maintain a good moisture level as the seedlings are shallow and dry out fast. Seedlings should be exposed to more sun and wind as the week progresses.
Starting Seeds That Require Stratification
“Winter Sowing” gives perennials that need stratification a head start.
Seeds that require a cold period before germination occurs (stratification) can be planted outdoors in February or early March using a method called “winter sowing.” Many perennials fall into this category. Milk or water jugs or lettuce leaf bins make ideal containers. They should be cut in half with drain holes added to the bottom. Potting soil or seed starting mix can be used to fill the bottom of the container. Seeds are planted according to packet directions. The container halves should then be taped up, leaving the lid off to allow for moisture, set out in the garden and essentially ignored until spring. The seed packet or a label taped on each container will come in handy when spring finally arrives and what was planted is a mystery. When seedlings are three to four inches tall, they can be sown directly into the garden.
Seedlings started under grow lights make it easy to start planting outdoors in the spring, and provide flowers and produce earlier than starting with seeds.
Article Resources:
homedepot.com/c/ah/create-a-diy-indoor-grow-light-system/
Create a DIY Indoor Grow Light System
theartofdoingstuff.com/grow-lights-for-beginners/
Grow Lights for Beginners; February 21, 2023 by Karen Bertelsen
growjourney.com/want-to-garden-like-a-pro-heres-a-simple-and-affordable-indoor-grow-light-setup/
Want to Garden Like a Pro; Here’s a Simple and Affordable Indoor Grow Light Setup, published January 2, 2023; updated January 9, 2024 by Aaron von Frank.
From Emerald Necklace Garden Club – Winter Sowing – Bottle seed starting method, gardeners.com/how-to/how-to-start-seeds/, Easy Plants to Start from Seed.
Photos courtesy of pexels.com and Emerald Necklace Gartden Club
