How Much Rain Did We Have?

There is something you need to know about me ... I'm a garden geek. Doing fieldwork while studying plant ecology in college has given me a mind that loves to observe, record, and make sense of the information. You are safe in assuming I keep garden records, and I think that qualifies me as a 'garden geek.'

Is there really a point to taking copious notes on what happens in the garden from year to year? Actually, yes. For one thing, insect emergence is tied to temperature. If I know when Japanese beetles appeared this year, I can give you a reasonable idea of when to expect them next year, as long as the temperatures next year are nearly the same. This holds true for most overwintering insects - both pest and beneficial. Since insects are cold-blooded, their metabolism is tied to temperature, knowing daily average temperatures can help you calculate when the emergence is likely to occur.

Soil temperature also affects seed germination. An old timer might tell you to plant green beans when oak leaves are the size of a squirrel's ear. Okay, but a soil thermometer is more useful. Where did this lore come from? A tree's leaves begin to unfurl when they are receiving sap from the roots, and the roots take up water when the soil gets to a certain temperature. Thus, when the soil temperature is 60^oF, bean seeds can begin their development, which coincidently, is also when oaks' leaves are unfurling.

When was your last frost this year? Mine was a couple weeks before Mother's Day, even though the second Sunday in May is the day we use as a guide for setting out frost intolerant plants. About a decade ago I started planting a short row of 'sacrificial' green beans at the end of April and this year I had an early crop. Is this a fluke or a sign to things come? Keeping track of temperature helps determine whether this trend is becoming the norm.

In general, average temperatures have become warmer over the last 40 years, and increasing temperatures creates problems for gardeners. Warmer temperatures mean insects that normally migrate from overwintering in the south get here earlier. It might also mean that some fast reproducing insect pests can sneak in another brood since their metabolisms are operating faster at warmer temperatures.

For the plants themselves, the warming temperatures have been causing more heat stress in recent years, especially when accompanied drought. Plants' metabolism is also tied to temperature, but many do not have mechanisms to survive excessive heat. As hot as the daytime temperatures are, the high overnight temperatures stress plants more when they are trying to recover from too much daytime heat.

If you plant seeds for a fall garden, you really watch the July temperatures carefully since many fall plants need cool soil temperatures to germinate. When you see that there will be a few cool days, be ready to quickly get seeds in the ground, water well and use row cover or shade cloth to keep the soil cool.

While the increasing temperature trend has been somewhat predictable over the last several years, rain has not. Depending on where you garden in Adams County, you probably had too much, or too little, or both! But when does this rain occur? My records show that we usually have a wet period in the spring, though not always during the same part of spring. In the summer, storms from the west and northwest give some gardeners no relief, while others get a day or two off from watering. Storms bringing tropical moisture from the south? Now, that is rain! Often too much rain.

There are downsides to heavy rain beyond the garden being too wet to work afterwards. If your garden has even the slightest slope, heavy rain moves soil particles and mulch downhill. Nutrients leach from the soil, too, causing a decrease in fertility. Humidity is not the gardener's friend, either. When you anticipate a stretch of humid weather, you can prepare for more plant diseases problems. On the other hand, a freshening breeze out of the northwest makes garden chores more comfortable and fungal plant diseases less of a threat, but it dries the soil out more quickly.

Weather changes day to day, but climate is the pattern of average temperature and precipitation over an extended period of time. The average temperature is generally warming and the atmosphere is holding more water; together this leads to more intense and less predictable weather. Record keeping helps us have an idea of what to expect in terms of weather trends and this helps the gardener be prepared for the chores that weather dictates.

One doesn't have to be a garden geek to jot down notes every few days. A good place to keep notes is in a computer spreadsheet, though I still prefer writing mine in an engagement calendar. Either way, being observant of the physical conditions in your garden space, looking for trends and relationships between the physical conditions and how the plants react, and anticipating a problem or opportunity enhances a gardener's success.

Oh, as of 9/27/21, the September total for my rain gauge was 14.7 inches. According to the National Weather Service (Harrisburg station), the average rainfall for September in Central Pennsylvania is 5.47 inches."

Debby Luquette is a Penn State Master Gardener from Adams County. Penn State Cooperative Extension of Adams County is located at 670 Old Harrisburg Road, Suite 204, Gettysburg, phone 334-6271.

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