The Secrets to a Great Windowsill Garden

potted plants on a windowsill in bright light

Growing a garden indoors tends to be limited due to space and light restrictions, especially in the winter. Houseplants will do fine stuck in the corners and on top of desks, but vegetables and herbs need a good amount of light, and do best when placed close to a south-facing window. Here are ten secrets to creating a great windowsill garden.

Light

plants next to a large indoor window

The first and most important step to a windowsill garden is finding the right window. Choose a south-facing one that gets at least five to six hours of sunlight a day. If you don’t have one, or it’s blocked from receiving full sun, you’ll want to invest in a grow lamp to help your plants produce food. If they don’t get enough sun, seedlings will get leggy, and their yield will either be minimal or nothing at all. Mature plants will go dormant and only reserve energy for producing greenery.

Containers

You won’t have a ton of choices when it comes to what will fit on a windowsill, but you can have fun with the style. Four-inch terracotta pots are a classic look and great mediums for indoor plants. Plastic pots will do just fine, but watch for metal ones as they will eventually rust. Planters designed specifically for windowsills may give you more space to work with, and you could even challenge your DIY carpentry skills, and build out the window ledge to hold something bigger.

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Soil

plants growing in rich soil in windowsill containers

Choosing the right soil is so important when it comes to indoor growing. Many people think they should use garden soil since they are growing food. Not so! Garden soil is meant for the outside where it can drain and plants can grow deep roots. It’s too thick for indoor pots and planters, and will suffocate shallow root systems. Germinating potting mix is best for seed-starting, then use potting mix anytime you are growing in pots or planters.

Herbs

Herbs will do well in a windowsill that gets around six hours of sunlight, but some will need more light than others. Sun-loving species like basil, sage, and oregano will do okay for a while, but may need help from a grow light, while parsley, thyme, and mint are cold-tolerant (helpful if you have drafty windows) and will flourish without extra help from grow lights. Herbs don’t require a lot of space to grow, so you can get away with planting two or three in the same pot or planter. Choose ones that compliment each other, and require similar water and light needs.

herbs growing in pots by a window

Vegetables

Choosing the right vegetables to grow will set you up for success. Sun-loving veggies like tomatoes and peppers will struggle even on the sunniest windowsills. It’s fine for seedlings, but even then, they will get leggy and thin after only a few weeks. Supplement with a grow light if you have your heart set on colorful veggies. Otherwise, stick to species that are considered shade-loving vegetables like lettuce, kale, spinach, and arugula. Microgreens are also great choices – you could get enough fresh greens all winter long with just a microgreen planter. Edible flowers can be fun, too!

Fruit

This is a tricky one, as most fruit needs a lot of sun and space to grow. That said, not all windowsills are small rectangles, so if you have a larger area like a bay window, then you may be able to get away with growing dwarf varieties in small containers. Lemon and avocado trees can be started on a windowsill but will outgrow the space within a year or so, and will not bear fruit. Pineapples can be propagated and set on a windowsill for their greenery, as well, but will need outdoor summer sun to ever make another pineapple. Strawberries would be your best bet if you want to try growing in a regular-sized planter, but again, a strong grow light will be necessary.

Water

hand using small watering can to water plants by a windowsill

The great thing about houseplants is that a lot of them can be forgotten about for a week or so, especially in the winter as they require less water. Don’t make this mistake with your windowsill garden! Most of the things you grow will want a fairly moist soil medium—not too wet, but not too dry. If you are experimenting with any tropical fruit, they tend to prefer a dry out period before a big soak, like their native settings. Research each plants' watering needs and be very specific with your regimen.

Humidity

Some might think this refers to the amount of watering, but it’s a separate issue for plants that are grown indoors. In the winter a lot of heating sources pump out dry, hot air and leach the environment of natural humidity (if you have radiant heat, count your blessings). Heat registers tend to be placed directly under windows, as well, which can send up blasts of dry heat directly at your plants. Misting may help combat this, but a humidifier is the best solution as it keeps humidity levels nice and steady.

Fertilizer

indoor plant garden fertilizer

As plants grow, nutrients are depleted from the soil, thus requiring a boost with an organic fertilizer. Every vegetable or herb will be a little different in their needs, but an all-purpose will do just fine if you find it confusing at first. Pay attention to the ratios “N-P-K” (nitrogen, phosphorus, potassium) and choose something mostly balanced. Leafy greens tend to want more “N” as it’s responsible for healthy greenery, but too much will burn them. Fertilize every two weeks on average for healthy growth.

Pest Control

Your plants aren’t safe just because they are grown inside, in fact, it’s where pests thrive due to lack of competition from other beneficial insects. Fungus gnats love moist soil and organic material and will set up shop if you aren’t careful. Thrips and spider mites are other things to watch out for. A small infestation won’t take out your crops, but you have to act fast. Always use fresh, new, organic potting mix, seal up the bag, and store in a cool, dark place. Keep the area clean of debris and rotting material: do regular vacuuming or sweeping around the area, as dust and dirt particles are breeding grounds for pests. Keep insecticidal soap spray on hand.

Gardening doesn’t have to stop when the weather gets cold, but finding the right place to grow edible plants can be tricky. If you have a sunny window, you’re on your way to creating a great windowsill garden. Just remember to follow these tips, and you’re sure to have fresh, healthy food all season long.

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