January

Lettuce in the midst of winter

Maryland Grows3 Comments
hydroponic lettuce under a grow light
Hydroponic lettuce under a grow light.

Homegrown lettuce in the dead of winter or the heat of late summer? It’s possible with hydroponics. And you don’t need a fancy setup with electric pumps and a water circulation system. The Kratky method lets you do it with a grow light and an empty coffee bin. 

Developed by horticulturist Bernard A. Kratky of the University of Hawaii at Manoa, the Kratky method is ridiculously simple. Plant roots need access to oxygen. When grown outdoors, a plant’s roots find this oxygen in air pockets within the ground. In a commercial hydroponic system, pumps circulate air to the plants’ roots. In the Kratky method, an air pocket is formed as the roots take up water, lowering the water level. This air pocket provides all the oxygen a plant needs at the root level.   

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Indoor lighting options: terms, types, and measurements

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terrarium plants under LED lights
Terrarium under LED lights. Photo: M. Talabac

This is the third in our four-part series of articles about indoor lighting for plants. You can also read the first, second, and fourth articles.

Artificial light sources come in several forms, all relatively easy to acquire. Costs can vary wildly, and some are more electrically efficient than others. The variety of available options allows you to customize setups to your needs and the preferences of your plants. Before you dive into an overwhelming list of web search results, here are traits of the basic categories:

Light-Emitting Diode (LED)

  • best energy-efficiency in terms of light produced per watt consumed (especially if the light has the ideal spectrum)
  • coolest to the touch except for high-powered units, which usually have small built-in cooling fans
  • can be expensive for high-quality fixtures, though costs are decreasing
  • light output does not dim significantly over time, though diodes do have a finite lifespan
  • reach full brightness immediately or very quickly when turned on
  • diodes can either be exposed or under a frosted or textured cover to help diffuse the light
  • diodes are directional, meaning they don’t emit light in every direction the way a fluorescent tube does, so reflectors aren’t usually needed
  • more even light output from one edge of the fixture to the other
  • can be round like a spotlight (with a cluster of diodes) or straight strips (or strips inside a tube) with one or more rows of diodes
  • some replacement “tubes” can be used in place of fluorescent tubes in a fluorescent fixture, but you must check with the fixture’s manufacturer for compatibility as mixing components is a matter of electrical safety
terrarium LED spotlights
Terrarium LED spotlights. Photo: M. Talabac
LED panel lights
LED panel. Photo: M. Talabac
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January Tips and Tasks

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Snow covered shrub

  • Heavy snow and ice loads can damage shrubs. Using an upward motion, gently sweep snow loads off of shrubs to prevent breakage. But oftentimes bent or weighed down branches will spring back after the snow/ice melts.
  • Problem tree branches (hanging very low or storm damaged), may be removed as needed. It is not necessary to wait until spring for this type of pruning.
  • Cut back or stop fertilizing houseplants unless they are grown under supplemental lighting.

Houseplant

  • Avoid the temptation to start seeds too early. Check seed packets for detailed information on starting various types of flowers. Do not depend on window sill light to grow these seedlings. Refer to our instructions on starting seeds indoors.
  • Don’t store firewood inside your home. Only bring in enough to burn at one time. Bark and other wood-boring beetles may emerge inside the home.
  • Be on the lookout for spotted lanternfly egg masses on the trunks of trees.

Spotted lanternfly egg mass
Spotted lanternfly egg mass
Photo: Emelie Swackhamer, Penn State University, Bugwood.org