CO-Horts Blog

Monday, March 30, 2020

Illuminating indoor gardens

Posted by: John Stolzle, Jefferson County Extension 

One of the great challenges I’ve faced with my indoor garden is light, or rather the lack thereof. At times, I view my indoor garden as low productivity time sink; but at other times I've noticed that it can be pretty fun to have such a variety of plants to tinker with and train from the comfort of home. An indoor garden can offer (a few) fresh tomatoes and herbs, and green colors in the middle of winter. And personally, in my apartment, in the middle of a city, I definitely enjoy the extra connection with nature that it brings.
My indoor garden is often a disorganized mess of green. On the bright side, I am able to harvest a few small bunches of cherry tomatoes every month.

When plants don’t receive adequate light, they become more susceptible to disease, their leaves can become pale and discolored, some will even drop leaves which further reduces their ability to absorb light. This low-light leaf drop feedback loop has resulted in the failure of many of my indoor plant experiments. Light intensity also plays an important role in a plant’s production of lignin, a scaffold-like component which plants produce to support themselves. Without proper light, many plants will often flop over due to weak structural support. Twine, twist-ties, or string can be used to help support a weak plant. 

This 'Purple Passion' (Gynura aurantiaca) bolted earlier in the spring. Using some twine and makeshift stakes, it has now become a 'spiraled' purple passion.
Compounding the issue of inadequate support structures, many plants can exhibit strong shade avoidance mechanisms. These mechanisms often manifest in a plant putting more energy towards the development of fast-growing elongated shoots and can result in spindly or “leggy” plants. The Purple Passion in the image above, for example, bolted and grew many inches within a just few weeks.

Increasing light (or PAR - photosynthetically active radiation) to adequate levels for a given plant can resolve these issuesGrow lights can be used to accomplish this or to mitigate the effects of low light conditions.

Even with these lights, the plants in my garden do not receive as much light as they would if they were planted outdoors. The lights just help mitigate some of the problem. 

Light Types:
Many options such as LEDs and fluorescents are available for homeowners to purchase. Decisions regarding 'which light is best' should be based upon individual situations, and factors such as the needs of the plant, energy consumption, heat, quantity of ambient light, and position of the to-be-installed grow light in relation to the plants. Below, I have provided links to pages which discuss these topics in more detail: 
A few last minute tips:
  • Help the plants support themselves. A small trellis, cage, or other structure can give the plants something to climb on.
  • It is very easy to overwater indoor plans. A general recommendation is to only water when the top 1-2 inches (2-5cm) of soil are dry. 
  • Scan with some regularity for pests and disease. Indoor plants often face significant challenges regarding pest infestations (especially of spider mites & aphids) due to a lack of natural predators that could otherwise help keep pest populations in check. Catching a problem early on can save lots of headache and potentially prevent the loss of a plant.
If you are interested in indoor gardening, you may appreciate these other posts in this indoor blog series: 

No comments:

Post a Comment