Growing edibles in window boxes is a great way to supplement your diet and grow some really delicious and nutritious food in a limited space. Gardening in window boxes is great for urban gardeners and those who don’t have the time or resources to grow food in a larger space. It is really amazing how much food can be grown in a limited space and how many common herbs and veggies are actually quite content in window boxes.
There is also great pleasure in growing some of your own food. Planting, caring for and reaping the harvest is a great experience for the whole family and helps everyone feel just a little bit more self-sufficient.
What to grow in window boxes
Here is just a sampling of some of the things you can grow in window boxes. The best plants are ones that have a shallow root system.
Herbs of all kinds have traditionally been grown in boxes on kitchen windowsills. There is just something quaint about growing a window full of herbs. Not only do they brighten your kitchen but they are also handy for adding to all of your culinary delights. Herbs love a haircut and will gladly allow you to nip away at them as you cook. You can also grow many herbs seasonally outdoors, or if you are lucky enough, year round if your climate is temperate enough.
You can grow a large variety of herbs in window boxes, enough for instant use and plenty for drying. Fresh herbs, incidentally, have entirely different flavors than their dried counterparts, but we often make do with the latter because it is much easier than stocking fresh ones. When you grow them, you can have both.
Grow parsley, basil, oregano, thyme, sage and mint varieties. You can either have a mixed planting or plant them in separate containers kept in the same box. It is possible to grow even tropical herbs like ginger and turmeric as long as you can bring their containers inside when it gets cold.
They look good in window boxes with their white flowers against the pretty leaves and the bright red berries spilling over the boxes. You can grow everbearing and day neutral varieties on a sunny, south facing window to get a staggered crop. They thrive in the sun. Alpine strawberries may be better if the window boxes are in partial shade most of the time.
Give strawberries a rich, well-draining potting mix with plenty of organic matter. Slightly acidic soil with pH level of 5.5 to 6.5 is ideal. You can add your coffee grounds to their containers.
Strawberries grown in window boxes usually remain disease-free on account of getting good air circulation in their exposed position. Don’t plant them with tomatoes, though. Pest problems are rare.
By definition, they are edible seedlings just putting out their first leaves. But in nutrition, they are far ahead of the mature plants that we normally use as vegetables. Unlike sprouts that are eaten roots and all, microgreens are harvested by cutting off only the top growth. And, unlike sprouts, they are grown in good light and out in the open, which helps avoid many pathogens that cause food poisoning.
Microgreens are ideal for growing in window boxes. All you need is some all-purpose potting mix because most of their nourishment comes from the nutrients stored in the seeds. Another plus is that they get ready within one or two weeks of sowing the seeds. You can have several batches back to back, and you will get a substantial crop each time. Their variety is amazing, and they will keep you in fresh salads all through the growing season.
Shallow window boxes are sufficient for growing microgreens because you will be growing them in small tubs or trays that can be lifted off as they become ready for harvest. You can recycle plastic tubs that salads and other food stuffs come in. Fill them almost to the top with soil or a soil substitute like peat moss. Sow the seeds and cover it with a layer of perlite and tamp down. This is to prevent the plants from touching the soil. Use a generous amount of seeds to get a maximum yield from minimum space. Water thoroughly with a fine spray and keep the tubs in the dark until you see sprouts pushing upwards. Transfer them to the window boxes, and wait until they are just growing their first pair of true leaves.
Some of the popular seeds for microgreens:
- Red amaranth
- Daikon radish
Greens for the salad bowl and cooking
They are excellent for window boxes even when they are in partial shade. Many of them have short crop duration, so you can have several batches. Pick just the mature leaves for your use and the plants will continue to produce more. Shallow rooted ones can be grown with other deep rooted veggies to optimize space utilization. Try growing:
- Leaf lettuce
- Green onions
- Swiss chard
- Bok choy
Since window boxes are open to the elements, you can grow only seasonal vegetables, unlike what you can grow on the other side of a sunny window. But ample sunlight and good air circulation between the plants can ensure sturdy growth and some protection from diseases that commonly affect the vegetables grown in the garden. Shallow-rooted vegetables are best because most window boxes may be only 1 ft. deep.
The length of the growing season is limited by your USDA zone, so you should look for varieties that do best in your area. Use good quality potting soil with some long-release fertilizer. You want to give your plants as much nutrients as you can within the limited amount of soil available to them.
These are good options:
- Cherry tomatoes
- Sweet potatoes
How to maximize yield
Get the largest, deepest window boxes suitable for your windows
The more space they have, the more soil and plants you can accommodate. Make sure that the boxes have sturdy supports as soil and plants together can weigh quite a lot.
Use the best quality soil you can get
Nutrient-rich, well draining soil helps your plant to grow vigorous roots and shoots and avoid diseases. Lighter soil substitutes like coco-peat and moss are ideal for window boxes, when used along with soil or by themselves. But they should be fortified with all essential plant nutrients.
You can grow plants closer together in window boxes because constant breeze ensures excellent airflow between plants. This prevents many diseases that would otherwise plague crowded vegetable patches.
Try mixed plantings
Grow plants that differ in height and root depth to take maximum advantage of the available space. Plants that can spill over edges and allow more space for others should be planted closer to the sides of the box. For instance, plant sweet potatoes with shallow-rooted plants like lettuce and spinach. Allow the sweet potato plants to hang out of the box so that the greens get all the space to spread their crowns.
Constant breeze and exposure to the sun quickly dries out the soil in window boxes. You can add a thick layer of mulch to protect the topsoil, but keep checking frequently. Plants wilt faster when it is both warm and windy. They can recover sooner if soil has enough moisture. Set reminders to stay true to a regular watering schedule.
Provide excellent drainage
Drainage is very important for plant health. Most plants––other than bog plants and marginals––hate wet feet, many of them succumbing to root rot if they are allowed to sit in wet soil for long.
Follow a proven feeding schedule
The correct feeding times for best yield have been experimentally worked out for different veggies by agricultural scientists. Following the feeding schedule for the plants you grow may ensure excellent yield. When growing veggies organically, the general rule is to give nitrogen-rich manure during vegetative growth and increase potassium with wood ash or kelp meal as they get ready for flowering and fruit formation.
Grow early-maturing varieties
Selecting early-maturing crops gives you more chances of putting in another crop as soon as one is harvested, making it possible to grow several crops back to back in a given season.
Nutrient intake differs between plants. Every crop depletes the soil of some nutrients, so it makes sense not to grow the same crop again. With trial and error you can work out a suitable order of planting to get optimum yield. The potting soil in the window boxes should be changed frequently, preferably after every growing season.
Challenges of vegetable gardening in window boxes
It goes without saying that you may face some challenges when you start growing edibles in window boxes.
Too little or too much sun
Not all windows are the same when it comes to growing edibles. For example, an eastern exposure gets morning sun, but it may become too shady once it is past noon. Northern exposure gets the least amount of sunlight while south and southwest facing windows get the maximum. You can get ornamentals suitable for all these lighting conditions, but your choice of vegetables is rather limited. They generally need plenty of sun to give a good yield because the food is made using sun’s energy. However, these general tips should help.
Leafy vegetables can do with less amount of light compared to fruiting vegetables like tomatoes and peppers. They may put up good vegetative growth when they get less light, but it would be very disappointing when you end up having a poor yield. Reserve them for southern and southeastern window boxes. Strawberries also may need as much sun as they can get to give a good crop. If it gets too hot or sunny for them, use adjustable awnings to control the sunlight.
If north-facing windows are your only option, aim to grow edibles for your salad bowl, greens and microgreens included. The light needs of root vegetables fall in between fruit-producing veggies and greens. Carrots, beets, radishes, and parsnips do very well with half a day in the sun, so you can consider them for east-facing windows. Alpine strawberries can probably do well here.
Too little space
Your success at growing some edibles in window boxes may fire up your enthusiasm to try all types of veggies, but space constraints can spoil your plans. Although there’s no harm in trying different veggies to see what works best for you, there’s the danger of choosing the wrong type of plants, only to end up feeling cheated and ready to give up.
No extensive research has been done to identify what you should and shouldn’t try to grow in window boxes, but these tips from veteran urban gardeners should help. Consider planting the following:
Edibles that you use in small amounts
When you have limited space, you should think of growing things that give you satisfaction with a small crop. If you can’t get enough of a vegetable crop to make a meal out of, chances are that you’d be disappointed with the whole project. For example, one or two bush bean plants may not give you sufficient pods at one time since they may be at different stages of growth. You will have to pick a few at a time and then store them until more beans reach the correct stage for picking.
Herbs are great for window boxes for this reason. You don’t need a lot at a time, but they would be there whenever you need them. Grow the ones you regularly use; basil and oregano if you make pizzas and pastas regularly, chives and dill for your potatoes and cilantro for Chinese dishes. Hot peppers and cherry tomatoes are great too because you can make do with a just a few.
Vegetables that you really like to eat
No matter how easy it is to grow radishes, there’s no point in planting them over and over again if you hate their taste. But it doesn’t hurt to try it once because there’s a reasonable chance that you may end up loving them once you eat what you grew.
Choose the greens that you love and go for vegetables you like to eat raw. That will make your efforts worthwhile because you will never get them fresher from anywhere else.
Vegetable/fruit varieties not commonly available
Sometimes supermarket shelves could be overflowing with a seasonal crop, let’s say, strawberries of a particular variety. When it sells for $1 a pound, you might find it hard to justify all the time and effort you spent at nurturing the same variety that gave you less than a pound of fruit altogether. Although definitely healthier, they may not be as big and shiny as the ones in the shop.
Don’t assume that commercial varieties are the best. There are more flavorful and more delicious ones out there that’s worth spending your time on. Also, look for cultivars that are very early or very late bearers. Try growing a vegetable that is rarely seen in markets, such as jicama or Chinese artichoke.
Wind damage and dust and dirt collection
Pests are rarely a problem in window box gardens, but they may have other problems. Their highly exposed position, especially in high-rise apartment buildings, makes them prone to wind damage. Attaching side panels to the windows may offer some shelter, but check whether it is against building rules.
Dust and dirt from the street can settle on the leaves, making them less efficient. Spray the plants frequently to clean them.
Window boxes are for all to see, especially when they are facing the street. You may want to ensure that your veggie-filled ones don’t decrease the kerb appeal of your home. A little planning can take care of that.
Avoid plants that require staking, and promptly remove scraggly looking plants that are at the fag end of their useful lives. That includes tomato plants with the last few tomatoes. You can harvest them a bit early and ripen them in brown paper bags.
Plant a row of marigold or pansies in front of the vegetables. Their cheerful flowers are always welcome sight. Marigold may protect the veggies from pests too. Use sweet potato vines with decorative leaves to create interest. Maintain symmetry and pattern by using the same arrangement of plants in window boxes on both sides.