Learn How to Start Seedlings on a Windowsill

Get your garden started indoors.
Tomato Seedlings in Pots

Tomato Seedlings Grow on Windowsill

If a grow light is out of the budget for starting seeds, a windowsill can work instead. To help your seeds germinate, place them in a spot that stays consistently warm — on top of the fridge or a radiator are good options. Shift them to the sunniest south-facing windowsill you’ve got as soon as a bit of green is showing above the soil line. If your windowsill is drafty or cold, lay down a towel or old t-shirt like a blanket and then set your pots on top. Location A south-facing window is your idea

Photo by: Shutterstock/Skeronov

Shutterstock/Skeronov

In this feature, garden authority Gayla Trail, the creator of YouGrowGirl.com, answers frequently-asked questions and offers gardening advice.

QUESTION:

I don’t want to go to the expense of setting up lights; can I start seedlings on a windowsill?

ANSWER:

Absolutely! To be fair, a grow light set up is ideal since you have greater control over growing conditions, most especially light. Since we can’t all afford the cash or the space to begin with, there is no reason why you should discount your windowsill as a seedling nursery until you are ready to step up your game. Fortunately, I have tricks that can help!

Growing Conditions

I know all too well from personal experience that not all windowsills are created equal. Many are wonky and uneven or too thin to hold pots, and some new-style windows don’t come with a sill, period! Worse still are the fluctuating temperature swings caused by baseboard heaters, drafts, and freezing glass. A windowsill can be the coldest place in your home or the hottest depending on a variety of factors. Unfortunately, spastic growing conditions can stress out sensitive young plants, leading to disease and death.

Tricks

Fortunately, most seeds require heat, not sunlight to germinate. Start your seeds in a spot that stays consistently warm — on top of the fridge or a radiator are good options. Shift them to the sunniest windowsill you’ve got as soon as a bit of green is showing above the soil line. If your windowsill is drafty or cold, lay down a towel or old t-shirt like a blanket and then set your pots on top.

Location

A south-facing window is your ideal. To be honest, anything else is going to get gnarly. I’ve had some success on less-than-ideal windowsills, but only with older seedlings that got a good start elsewhere. Plants grown underneath grow lights receive bright light from above as they would outdoors. Windowsills receive sun on an angle, causing plants to grow in the direction of the light. If the light is feeble the plants will grow lanky and weak as they stretch themselves in an attempt to get to it. The time of year will also affect your chances.

Tricks: Utilize east- or west-facing sills later in the spring when the day length and intensity of the sun has increased. Turn plants daily so that they receive equal light on all sides.

Plants

Some plants do better on windowsills than others. For example, tomatoes tend to be fairly forgiving and unlike most plants, lanky stems can be buried at transplant time. You’ll have the best luck overall with plants that will only be spending a few weeks at most indoors. Cucumbers and squashes are decent edible crop candidates as are cold hardy onions, kale, and broccoli since they can withstand temperature fluctuations. I’ve had good success with marigold, zinnias, and cosmos and a number of tough herbs including parsley, chives, summer savory, and chervil. There is no use bothering with radishes, beans, lettuce greens, peas, dill, and coriander. Save yourself the hassle and direct sow them outdoors!

Next Up

How to Grow and Care for Sago Palm

Our garden experts offer sago palm planting, growing and care tips for this ancient plant.

How to Grow Rice

Learn how to cultivate a worldwide staple and ornamental plant with these easy-to-follow instructions.

Hen and Chicks: All About These Popular Succulents

Learn how to care for and propagate this popular, cold-hardy succulent.

How to Grow Daylilies

With some advance planning, you can have glorious daylilies for spring by planting in the fall with this advice from HGTV gardening experts.

How to Plant a Tree

To give your new tree a good chance for success, follow these simple instructions on planting a tree.

How to Propagate Plants

Propagating plants is easy. Plus, learning how to propagate plants can save you money you'd otherwise spend on buying new plants.

How to Grow Asparagus

Learn what's needed to grow asparagus from planting seeds and crowns and get advice on harvesting asparagus.

How to Plant and Grow Marigold Flowers

Easy-to-grow marigolds add bright yellow, gold, orange and creamy-white color to gardens and containers from spring into fall.

Planting and Growing Bell Peppers

Grow delicious bell peppers from seed or seedlings with these expert tips on everything from planting peppers to harvesting.

How to Plant Dahlias

Learn the basics of planting dahlias — including simple tips to improve your success.

Go Shopping

Get product recommendations from HGTV editors, plus can’t-miss sales and deals.

On TV

Follow Us Everywhere

Join the party! Don't miss HGTV in your favorite social media feeds.