Thursday, February 16, 2012

Weather Tools for Gardeners

New Hardiness Zone Map Available

The USDA recently released new plant hardiness zone maps. Anyone can download maps like to one at left at no cost. With a broadband connection, you can use a nifty interactive map.

Find all the new maps at this USDA site. 

The interactive map has multiple layers that can be altered to provide different views. You can choose a simple physical map like the one at left, or a 3D image of the terrain, or a satellite photo, with or without street and place names. Hardiness zones are shown in an overlay that can be adjusted to different transparency levels. The level of detail is incredible. Looking at our own site at the highest resolution, we can see that the high ridge to our north is typically half a zone colder than we are.

Besides the maps, the site has plenty of useful tips on how gardeners and farmers can use the data.

Backyard Weather Stations  


Having good weather information makes gardening a lot easier. Weather Underground has been a great resource for us for several years. In addition to weather forecasts for anywhere on the planet, the site has feeds from hundreds of private weather stations. Anyone can install a weather station in their backyard and share the data with weather enthusiasts all over the world via Weather Underground. The site has a cool feature that allows you to create a "weather sticker" to embed on a web site or blog, showing current conditions for any of the stations in the database. Check out the weather for Knoxville on the right hand side of this page.

Setting up your own weather station can be great fun, and the data from it can help you plan your garden with site-specific information. You can spend anywhere from a few dollars to several thousand on a home weather station. Here are a few tips if you decide to purchase one.

The lower priced models can be accurate. We have several and all seem to agree when placed side by side. I have also compared temperature readings using a research grade glass thermometer. All the digital ones are within a few tenths of a degree of the actual temperature, which is plenty accurate for gardening needs. For example, we have an indoor outdoor thermometer consisting of a base unit and wireless remote. Each day, the base unit displays the high and low temperatures for the previous day automatically. It also displays indoor and outdoor relative humidity. This device cost about $20 at our local DIY store.  These units typically lack the ability to record much information, however, leaving you to track trends with pencil and paper or a spreadsheet.

A few years ago we bought a fancier weather station for about $200. We ordered online. Several competing brands sell home weather stations and the price can range up to several thousand dollars. Ours came from Oregon Scientific, and while we could, shall we say, suggest some improvements, overall it has been quite satisfactory. Some friends purchased a more sophisticated system from OS, and have generally been pleased, as well. What these units feature is a USB port that permits capture of data to a computer. This feature vastly simplifies recording trends, and makes possible sharing your data via the Internet. The external sensors in our station require batteries, while the more upscale station our friends bought features solar powered external sensors. In both cases the sensors transmit data wirelessly to a base station.

Both units came packaged with software that proved to be out of date and hardly intuitive to use. Fortunately, we were able to upgrade the software online, and often find answers to our questions from the manufacturer's web site. Oregon Scientific, however, is useless if you have questions, in our view.

Changing batteries in the outdoor sensor for temperature, humidity, and wind data could not be simpler. You twist the plastic housing a quarter turn and it pops away to reveal the battery compartment. Done in 30 seconds or less. The rain gauge, on the other hand, has the batteries encased in a waterproof, gasketed housing that requires removal of eight tiny screws each time the batteries need changing. It is a genuine pain, and the reason we will go with solar-powered should we buy another station.

We have found another problem with all of the stations that feature wireless sensors. When the package states a maximum distance between the sensor and the base station, it means under ideal conditions. Depending upon the construction of your home and the presence of obstructions like trees and outbuildings, the actual range of the device can be much less. We are told by others with experience that more costly, professional quality weather stations typically feature much more powerful transmitters in their remote units.

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