Summer windowsill herb gardens offer easy access to fresh, delicious herbs without melting in our brutal heat, but just like any garden, getting started takes a little preparation. If you want to be top-tech about the endeavor, then by all means, invest a few dollars in a spectrometer and gauge the actual sunlight entering your windows. This might be critical knowledge, actually, depending on the age of your windows. Some newer varieties limit UV-spectrum so effectively that not even Mary’s garden will grow. If this sounds like your case, you can still grow indoors! Look into the many options for indoor plant-growing light systems. Our local community has amazing resources for this sort of horticulture. If, however, you have a sturdy, wide sill below a south-facing traditional-glass window, or a bump-out garden window, then you’ll just need to obtain containers, a growing medium and some seeds or starts for your indoor summertime herb garden.
Containers are largely a matter of taste, but some are better suited for sill gardening than others. Make sure your container has a system for catching water-runoff to prevent damaging the sill or causing the plants to sit in stagnant water. There are also very efficient self-watering containers with leak-proof bases. Keep in mind that you’ll want the leaves of the plants to be in the sun and the roots to stay shady and cool. I recommend traditional glazed clay containers with thick walls because they maintain temperature around root masses more evenly than thin or plastic containers.
The medium used to grow the plants is also up for discussion. Potting soil is specifically formulated to remain light, fluffy and hydrated inside of a container, but it isn’t necessarily great for the kitchen environment. It can harbor pests, germs or generally make a mess. Most garden centers sell some sort of potting medium that isn’t traditional potting soil—whether clay- or coconut-based—that’s sterile and effective as growing materials. Of course, if you’re a traditionalist and want to use potting soil, please do! (I do.) But we live in a golden age of gardening, and options abound.
Growing in a container means that nutrients for the plants must be supplemented, so add appropriate fertilizer according to your plant’s needs. There are plenty of organically derived herb- and vegetable-specific plant foods, so ask for an appropriate liquid or pelleted form when at the nursery. Be sure to mention that the food is for indoor use! Some sources of fertilizer are rather odiferous.
You can grow nearly any herb inside during any season, with appropriate conditions, so choose what kinds to grow according to your culinary tastes. Basil, thyme, oregano, chives, mint and cilantro are all very hardy and great choices. (You can even grow a bay tree in a very sunny spot inside your home, so explore your options, but be careful of moisture levels.) Plan on one plant per every four inches of container space, and keep the plant’s needs and your potting choices in mind if you tend to over- or under-water. Also, consider making use of different windows for different times of the year. No matter what, be sure to enjoy the constant experiment and learning process that is gardening—whether indoors or out.
By Sarah J. Nielsen