Fill the box up 2/3 of the way with potting soil.
Strawberries. In Medieval times strawberries symbolized prosperity, peace, and perfection. Through history they have also be considered aphrodisiacs, and some lore has it that Native Americans taught settlers how to sweeten cornbread with strawberries, and this was the inception of the strawberry shortcake. What is undisputed about strawberries is that they have no fat, very few calories, yet are rich in vitamin C, potassium, folic acid, fiber, and vitamin B6. And very few things taste better than a perfectly ripe strawberry.
Types of Strawberries:
Primarily, people grow three different kinds of strawberries: June Bearing strawberries produce one large crop in early summer. These are the biggest berries and their root system is on runners and the plants spread easily. The other two, Everbearing and Day Neutral, produce berries from spring into fall, and these are the most practical for reaching out your window so you can pluck a berry or two to add to your yogurt in the morning. These are smaller berries than June Bearing, but still very sweet. If you have a shadier spot, you can try growing Alpine Strawberries, a wild European variety that is small, but is a pretty plant and the fruit has a nice flavor. Two of my favorite heirlooms are "Yellow Wonder Wild Strawberry" and the "Alpine Migonette."
A real advantage to growing your own strawberries is that on commercial, non-organic farms large amounts of pesticides are used to grow strawberries. In fact, they are one of the most pesticide laden fruit to be found on grocery store shelves. According to the Environmental Working Group website, pesticides were found on 90 percent of the strawberries tested.
What You Need
Window box with drainage holes: To make drainage holes yourself you will need a drill or hammer and large nail.
- Potting soil
Landscaping cloth: Optional. These only come in large rolls, so it might not be worth it to buy an entire roll for your windowbox. If you see someone using a roll of it, ask them for a swatch.
Strawberry starts from your local nursery: You can also use seeds. I’ve listed two of my favorite seeds companies here, but strawberries can take a long time to grow. For small windowboxes, you will only need 3 plants per windowbox, so it doesn’t cost much more to just buy the plants at your local nursery. If you want to start your plants by seed, two of my favorite places are Renee’s Garden and Baker Creek Heirloom Seeds.
In temperate climates like Northern California, strawberries will grow and fruit year round. For climates with a hard winter, strawberries should be planted when it seems the last freeze has passed. If a snap freeze is going to hit, bring them indoors until it passes. They should grow and fruit until it starts freezing again.
Mix Your Potting Soil
Almost all garden centers sell excellent potting soil enhanced with everything from bat guano to seaweed. Since you are planting things you will eat, don’t skimp on this and buy organic. There are many different ways to mix your own potting soil, but the main components you want from your materials are elements that keep the soil lightweight and well drained, like vermiculite or perlite. The soil also needs an element that will hold moisture, like peat moss or humus. This is important, as pots tend to dry out faster than the ground and the smaller the pot, the faster it dries out. Worm castings also provide humus that help retain moisture. The more you water, the more you will need to add nutrients, as these drain out of the soils. And the smaller the container, the more you will water, so keep your worm castings coming.
To make your own potting soil, start with 1/3 rich, organic soil. Add 1/3 vermiculite or perlite and 1/3 worm castings.
1. Make drainage holes in the bottom of your window box.
2. Cut a piece of landscaper's cloth and lay this on the bottom of the windowbox (optional). This just lets the water flow out, but holds back some of the potting soil.
3. Fill the box up 2/3 of the way with potting soil. .
4. Remove your starts from the container they came in and gently massage the roots, so they will spread more easily once planted. .
5. Place the starts in the window box, and space them about 3-4 inches apart. Then fill in around them with potting soil. Plant the strawberry starts even to the soil level—don't bury the stems or expose the roots.
6. Water them well after planting and keep the soil moist to the touch. Full sun is best, but during the hottest months be sure and give them extra water. Some varieties, like the alpines, tolerate partial shade.
7. They should produce strawberries during temperate months.
On Co-Planting: Sometimes I add tiny flowers to the box. I like how they look and they attract pirate bugs that eat pests that will harm the strawberries, although doing so means your strawberries will have a little less space, and may need to be replaced sooner.
About the Author:
Maria Finn has written for Saveur, Metropolis, Forbes, The New York Times, ABC.com, and The Los Angeles Times. She is the founder of Prospect & Refuge, a garden-design and installation firm and also writes the weekly newsletter/blog City Dirt, dedicated to adventures in urban gardening. Her newest book, A Little Piece of Earth: How To Grow Your Own Food in Small Spaces, will be released on February 16. She lives on a houseboat in Sausalito, California.
Other Posts from Maria Finn:
• How To Start A Home Worm Composting System
(Images: Maria Finn)