Leggy plants - Ask Extension
We always like to have a backyard garden and to save money we try to start the plants ourselves from seeds. However we always end up with leggy plants...
Knowledgebase
Leggy plants #892370
Asked February 06, 2025, 1:05 PM EST
We always like to have a backyard garden and to save money we try to start the plants ourselves from seeds. However we always end up with leggy plants like tomatoes and cucumbers . What are we doing wrong. Thanks
Wicomico County Maryland
Expert Response
Starting seeds too early can be one reason why they become leggy before they're ready to go outside. The other common factor is the intensity of the light they get while inside; if not strong enough, seedlings can lean or stretch (get leggy) and be prone to flopping over. Years ago, most seed-starting indoors was done under fluorescent lights, and while a few fluorescent fixtures are still available now, most options are LEDs instead. These have the benefits of less electricity use, less energy wasted as heat (compared to fluorescents and especially incandescents), a longer usage life, and are usually a more intense source of light, which is good for sun-loving plants like vegetables. Lights made for growing plants ("grow lights") are best, though sometimes multi-purpose lights (like "shop lights") can work just fine. There are multitudes of brands and products for LED grow lights on the market today, both in local stores and online. Some are similar in shape to fluorescent shop lights (2-foot or 4-foot tubes/strips) while others are square panels, round spotlights, or slender, shorter tubes/strips designed to fit over seed-starting trays.
It's hard to judge how well any light source is suited to growing plants by sight alone, since human eyes aren't able to fairly judge how bright the light is with regards to what plants need. (We have different sensitivities to colors of light than plants do, so what looks moderate to us might be dim or intense for a plant.) If helpful, you can explore our four-part blog series linked below about indoor lighting. It explains what some of the commonly-used specification terms mean that can be used with grow lights, and how to use them to select good candidates to try. The variety of terms may seem daunting and technical at first, but it's a handy way to sort-out all the lighting options for sale today.
The good news, in a way, is that light brightness drops dramatically with distance, so a light that you may worry is too bright or too dim can be adjusted (to a point) by merely moving the fixture or the plants further away from each other or closer together without having to change-out the light fixture itself. "An Introduction to Gardening Under Lights" is the first part of the four blog articles. While its focus is lighting for houseplants, it applies to seed-starting as well. You will still find some of the pink-blue combo LED lights on the market, and while they can grow plants fairly well, we recommend using white-looking lights (which still have the red and blue wavelengths in them that plants need), because it keeps the plants under natural-looking light so problems are easier to detect (such as leaves turning yellow due to malnutrition or pest issues).
Grow lights can be used by themselves as a plant's only source of light, or used in combination with natural light from a window to extend the hours of light exposure on shorter winter days.
Our Vegetable Planting Calendar can guide you as to when to sow seeds of different veggies so they aren't started too early. For example, tomatoes are often sown too early since gardeners are eager to get a head start on planting. This can be okay (to a point) if the grow lights used are intense enough to keep the plants in good shape until late spring planting, but in most cases, can promote legginess.
If you don't have the space or budget for using grow lights, use the sunniest window available to give seedlings the brightest light possible. Here too, the further from the light source, the dimmer the light (drastically dimmer as far as the plants are concerned), so keep the plants as close to the window as you can where they won't get a cold draft. Seedling heating mats, which gently raise the temperature of the tray on top of them by a few degrees, can also improve germination and help to compensate somewhat for a cooler growing location.
Both grow lights and a heat mat can be put on an outlet timer if they are used, so they give seedlings more consistent conditions. (As with anything electric, for safety, make sure the outlet or timer can handle the amp usage of all the things plugged into it; otherwise, plug them in separately.)
Miri
It's hard to judge how well any light source is suited to growing plants by sight alone, since human eyes aren't able to fairly judge how bright the light is with regards to what plants need. (We have different sensitivities to colors of light than plants do, so what looks moderate to us might be dim or intense for a plant.) If helpful, you can explore our four-part blog series linked below about indoor lighting. It explains what some of the commonly-used specification terms mean that can be used with grow lights, and how to use them to select good candidates to try. The variety of terms may seem daunting and technical at first, but it's a handy way to sort-out all the lighting options for sale today.
The good news, in a way, is that light brightness drops dramatically with distance, so a light that you may worry is too bright or too dim can be adjusted (to a point) by merely moving the fixture or the plants further away from each other or closer together without having to change-out the light fixture itself. "An Introduction to Gardening Under Lights" is the first part of the four blog articles. While its focus is lighting for houseplants, it applies to seed-starting as well. You will still find some of the pink-blue combo LED lights on the market, and while they can grow plants fairly well, we recommend using white-looking lights (which still have the red and blue wavelengths in them that plants need), because it keeps the plants under natural-looking light so problems are easier to detect (such as leaves turning yellow due to malnutrition or pest issues).
Grow lights can be used by themselves as a plant's only source of light, or used in combination with natural light from a window to extend the hours of light exposure on shorter winter days.
Our Vegetable Planting Calendar can guide you as to when to sow seeds of different veggies so they aren't started too early. For example, tomatoes are often sown too early since gardeners are eager to get a head start on planting. This can be okay (to a point) if the grow lights used are intense enough to keep the plants in good shape until late spring planting, but in most cases, can promote legginess.
If you don't have the space or budget for using grow lights, use the sunniest window available to give seedlings the brightest light possible. Here too, the further from the light source, the dimmer the light (drastically dimmer as far as the plants are concerned), so keep the plants as close to the window as you can where they won't get a cold draft. Seedling heating mats, which gently raise the temperature of the tray on top of them by a few degrees, can also improve germination and help to compensate somewhat for a cooler growing location.
Both grow lights and a heat mat can be put on an outlet timer if they are used, so they give seedlings more consistent conditions. (As with anything electric, for safety, make sure the outlet or timer can handle the amp usage of all the things plugged into it; otherwise, plug them in separately.)
Miri
