How to Grow a Window Box Vegetable Garden

A window box vegetable garden is a great way to utilize a small space to grow food. Once planted, all you need to do is water and harvest. Have fresh food at your fingertips this summer by planting a window box vegetable garden.

Growing edibles in window boxes is an ideal way to grow food without tending a garden. Container gardens are easy to care for, especially for those with physical limitations that may make digging in a garden difficult.

Container gardening will also help you avoid having to deal with poor quality soil, and you’ll be less likely to lose your harvest to hungry deer, ground hogs, and rabbits.

A window box for growing vegetables does not have to be attached to a windowsill. You can also fasten it to a balcony railing or fence. The containers can even be placed on your front steps, patio, or whatever space available.

Types of Vegetables for Window Boxes

Many vegetables are suitable for growing in a container and will produce big yields from a small window box. Plant choices will depend on the depth of the window box:

6-inch Deep Window Box: A 6-inch deep container can support shallow-rooted plants like Asian greens, bush beans, garlic, kohlrabi, radishes, leaf lettuce, green onions, peas, spinach, and Swiss chard.

12-inch Deep Window Box: Window boxes that are 12-inches deep can grow beets, broccoli, carrots, cucumbers, eggplant, peppers, potatoes, tomatoes, zucchini, and almost any other type of vegetable plant.

Dwarf or bush plants will take up less space and produce the same size vegetable as a full-size plant.

How to Choose Which Vegetables to Grow

Some plants are companion plants, which means they grow better near a compatible companion:

Asian greens, lettuce, radish
Beans, carrots, zucchini
Eggplant, beans
Spinach, chard, onions
Tomatoes, basil, onions

Avoid planting onions and garlic with beans and peas.

Also remember that you want to enhance the view out of your window, not block it, so low-growing vegetable plants will be ideal choices.

Steps to Growing Vegetables in a Window Box

Use these tips to successfully plant and grow a window box vegetable garden.

Step 1: Gather Your Materials

Window Boxes: Purchase or build window boxes that are at least 6-inches deep so the plant roots will have plenty of room to grow.

Soilless Potting Mix: A soilless potting mix is ideal for container gardening. It is lightweight, but will retain moisture and resist compaction. Do not use soil from your garden. It is too heavy and may contain disease spores and weeds that will thrive in a container environment.

Organic Granular Fertilizer: Your plants need supplemental nutrition to grow into healthy plants. If your potting mix doesn’t contain fertilizer, mixing organic fertilizer right into the potting mix will provide the boost they need to establish quickly and grow.

Fish Emulsion Liquid Fertilizer: Since the containers are small and watered often, nutrients in the soil need to be replenished frequently. A weekly feeding of liquid fertilizer such as fish and seaweed emulsion will keep your plants nourished.

Watering Can: Easy access to water will make caring for your window box garden much easier. A good-sized watering can will reduce the number of trips to the faucet for refills.

Seedlings or Seeds: Starting a window box garden with purchased seedlings or transplants you grew yourself will get you on your way to a quicker harvest. Even though growing vegetables from seed can take a litter longer, it is much less expensive, and you have more varieties to choose.

Step 2: Choose a Sunny Location

Try to find a sunny area that you will be able to access easily to water and harvest your vegetables. Most vegetable plants grow best with at least 6 hours of direct sunlight every day. South-facing windows are ideal for growing a window box garden, but an east or west-facing window will also work well.

If a north-facing window is all that you have, then select plants that will grow in low-light, like arugula, beets, broccoli, cabbage, carrots, cauliflower, celery, chard, garlic, kale, leaf lettuce, leeks, mustard greens, and parsnip.

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Step 3: Prepare Your Window Boxes

Position the window box a few inches below the window to prevent rain from splashing soil on the window. Test to ensure the window will open properly after window box is installed.

The window box will need several bottom drainage holes to allow excess water to empty out quickly. Add more drainage holes to box bottom if needed, and then attach the window box securely before filling it with soil and plants.

Place a layer of newspaper in the bottom of the box to prevent planting soil from washing through the drainage holes.

Pre-moisten the potting mix before filling your containers. Use a clean bucket or bowl and warm water to the soil mix. You will want the potting soil to be slightly damp, but not soaking wet. If you are using granulated fertilizer, now is the time to mix it into the potting soil. Follow the directions and combine it with the soil.

Fill the window box with pre-moistened potting soil to within about two-thirds full. Press gently to remove air pockets.

Step 4: Plant Your Window Box Garden

If you are growing different crops in one window box, try to group vegetables that have the similar watering needs and the same amount of sun exposure.

Planting Vegetable Transplants: With plants still in their original containers, place them on top of soil, and play with the arrangement until you are satisfied. Try to place taller plants in the back and shorter plants in front for optimum sun exposure.

Dig holes in the soil, remove the seedlings from their containers, and place into the holes at the same soil level. Add more soil around the base of each plant until roots are covered. Gently firm the soil with fingertips and water plants well.

Growing from Seeds: Review the seed package for information on how to sow your seeds for the best results. The package will tell you when to sow the seeds, how deep to sow the seeds, how far to space them out, and how far away to thin the seedlings once the seeds have sprouted.

Poke holes into the soil and plant 2 or 3 seeds per hole. Cover the seeds with soil, press down gently so the seed makes contact with the soil, and mist the soil surface with water. Keep the soil evenly moist until the seeds sprout, and then water when the top inch of soil is dry.

The plants need plenty of space to grow, so be careful not to overcrowd them in the window box.

Step 5: Caring for Window Box Vegetables

A container garden needs a few minutes of maintenance a day. Growing a window box garden makes it very easy to tend to the plants. Just open the window and you are in the garden.

Watering a Window Box Garden: Since the growing space is small and shallow, it will need to be watered daily, sometimes twice a day during the middle of summer. Water when the top inch of soil is dry.

Fertilizing Your Vegetable Plants: The plants are competing for food, so they will require a steady diet of plant food. Feed your plants weekly with an organic liquid fertilizer mixed according to the directions for container vegetables.

Provide Support if Needed: Tall and trailing plants, like tomatoes, pole beans, cucumbers, and peas may need some support such as a trellis or sturdy tomato cage.

Check for Pests and Disease: Inspect plants daily for pests or disease and treat immediately if anything is found. Pests or diseases will spread rapidly when plants are grown in close to each other.

Thin Plants: Crowded plants compete for water, nutrition, and air circulation. Thin your plants as needed by clipping the unwanted seedlings at the soil line. If you are thinning greens, toss these clippings into salads.

Enjoy the Harvest: Harvest frequently to encourage the plants to continue to produce. Harvest leafy greens by picking from the outside of the plants, and the center will continue to grow and produce more greens. Harvest fruits as they mature.