My indoor potted Basil plants keep dying. This could be because, a. I don’t live in a warm climate or b. I keep going away and leaving them to die.
Aside from needing to water my Basil plants more do you have any tips for coaxing growth from a cold a and frigid Basil…..
So, as I explained to her, productive indoor plants require as much sun as you can possibly give them. Ideally, they need up to 6 hours per day, or more, in order to produce anything harvestable. Plenty of indoor plants will grow in much lower light conditions than this, but the main difference is they don’t produce anything we’d want to eat (with the possible exception of the awesomely named Monstera deliciosa, but more on that later).
Now, probably the first vegetable people ever grow is the Carrot (Daucus carota) who in their life didn’t have a frustrated parent in the school holidays, or an enthusiastic young teacher in primary school, show them the magic of sprouting a cut off carrot top? You put the carrot top on some cotton wool on a window sill, and magically, green sprouts emerge from the remnants of out lunch or dinner! Of course, the plant is growing from stored energy in the tap root, as Carrots are biennial, they store the sun’s energy as starch in a fleshy root over winter, to resprout, flower and produce seeds the following year. If we left the carrot on the window sill it would eventually begin wilting, as the amount of water required by the foliage soon exceeds that provided by contact with the cotton wool, and the energy stored in the cut chunk is not enough to sustain the plant for long.
This indoor experiment highlights some of the problems with indoor growing. Root space is limited in pots indoors, though not to the extent of the carrot. The main issue is one of energy. Plants produce energy from sunlight, converting carbon dioxide (CO2) from the air and water taken up by roots (H2O) into sugar (COOH). In order to do this, plants need a reliable constant water supply, which is provided by the gardener, an endless supply of atmosphere, usually not an issue, and energy from the sun.
Indoor plants are often selected from species that naturally occur in low light areas, such as forest the floor. Plants naturally adapted to low light levels or filtered light adapt easily to indoor growth, and ferns are good example of these. In the 1970s, advances in tissue culture and micropropagation technology allowed for cheaper plants for indoor gardens from species that had been previously too difficult to propagate efficiently. Tissue culture is the process by which whole plants may be regenerated from single cells or small parts of existing plants. In effect it is a small scale version of the cloning used in plant propagation generally, allowing greater control of the environment on a very small scale, including temperature, humidity and light levels, as well as hormone manipulation to trigger various growth responses in the tiny plantlets.
However, most plants we consume as food are not adapted to low light conditions or the filtered light they might receive indoors. They require much higher light levels to produce the edible parts from which we in turn derive our energy. As I mentioned, preferably up to six hours a day are required, in a north* or east facing window. Less than this, and the plants will be less productive, and often become spindly as they respond to low light by stretching their stems in order to grow “out of the shade”. West facing windows are less preferable, due to the increased danger of the plants becoming too hot in the afternoon sun. (* In the northern hemisphere, a south facing window is best).
Some older style houses may be blessed with a sun room, or sleep out facing the sun, and these are often used by enthusiastic green thumbs to grow any number of plants. Many people choose to grow herbs, though most of these are suited to a full sun, garden position, many can be grown and harvested from a window sill, especially handy if it is in the kitchen. They are also a good choice, as many of them are “cut and come-again”, meaning they can be harvested several times, and will grow back after each haircut. Oregano and Marjoram (Origanum spp.) are good examples of these, as are
- Thyme (Thymus spp.)
- Rosemary (R. officinalis)
- Sage (Salvia spp.)
- Certain Basil varieties (Ocimum spp.)
- Chives & Garlic Chives (Allium spp.)
Most of these will have a less robust flavour if grown indoors because the volatile oils that make them taste good are produced in higher quantities in full sun. They also have a tendency toward becoming spindly, though regular harvesting will reduce the incidence of this.
Mint will tolerate much lower light than many of the other herbs, even in the garden. It’s one of the few things you can successfully plant in the shade and eat. There are a number of edible plants, for example Coffee (Coffea arabica) and Pineapple (Ananas comosus) that may be grown indoors for a period of time for aesthetic purposes, but ultimately must be moved outdoors in order to produce anything remotely comestible. The one exception I can think of is the exotic looking Monster Plant, or Fruit Salad Plant from Mexico, as mentioned above. A bizarre looking monocot related to Arum Lilies, and producing a fruit annually, indoors or out, with distinctive hexagonal sections. The only plant we know of in the world that has naturally occurring holes in the leaves, it really tends to look like something from another world, though as it has often been used in films for other worldly location setting, the association may have been made for me in the depths of my childhood subconscious.
While the fruit is delicious, and the plant easily grown (if very slow to mature) it must be noted that it will not live inside forever, as it has a maximum height of about 20 metres, though if the top section is removed, the plant will continue to grow. The fruit itself also contains a nasty surprise in the form of tiny black oxalic acid crystals which can sting the tongue of the unwary gourmet. I used to routinely give these plants as house warming gifts, my 70s upbringing leading me to believe a house without one was not a home.
Growing plants indoors is possible, and there are probably benefits to having tough, tolerant plants in living areas to help clean the air we’re breathing, but just remember they don’t like the same conditions as us all the time, and keep an eye on them for signs they are not coping, especially as seasons change. A stint outside in the sun may change their fortunes, if only during the day. For better or worse. Good Luck!