Down to Earth - by Madison Co. Master Gardeners
: Seeds come equipped with everything needed to create a new plant. They’re simply waiting for optimal environmental conditions to be met, then the process of germination can begin. First, the seed absorbs water. The seed coat softens and enzymes within are dissolved. Warm temperatures activate the enzymes to begin working. Oxygen combines with the seed’s stored energy and new tissue is formed through cell elongation and cell division. This description of germination, though over-simplified, gives us a useful glimpse of plant life in its infant stage.
· All seed germination involves water, temperature and oxygen. However, each plant species has unique requirements for these three conditions. Therefore, follow seed package instructions carefully. Days to germination and planting depth are important knowledge for successful gardening.
· Seeds are often started indoors in order to extend the growing season in our Midwest location. Seed starting in early spring also gives the gardener an opportunity to optimize conditions for germination. Soil temperature can be controlled through the use of heating mats. Watering from the bottom at appropriate intervals keeps the soil moist, not water logged.
· Moisture is a pre-requisite for successful germination. However, too much water will exclude oxygen from the seed. Note that seeds need oxygen during this stage of their development; the need for carbon dioxide increases later when leaves emerge and photosynthesis begins.
· Each species has an optimal temperature and a range of temperatures for germination. ISU Publication PM 874 “Starting Garden Transplants at Home” includes a table of best soil temperature for germination of several flower and vegetable species. Most indoor seed starting will be successful at soil temperatures between 75 and 90 degrees, with cooler temperatures at night after the seedling has emerged.
· When planting seeds directly outdoors, you have less control over water, temperature and oxygen. However, there are gardening practices you can employ to help nature along. First, plant seeds into loose, friable soil. Test the soil for moisture content by squeezing a handful. If the soil forms a ball that does not fall apart, it is too wet to plant.
· Cold season plants like spinach and kale can tolerate cold temperatures. Other seeds, for example beans and corn, risk rotting if planted into cold, wet soil. Consult ISU Publication PM 534 Planting and Harvesting Times for Garden Vegetables” and seed packages for appropriate planting conditions.
· Planting depth is important. A general rule is to cover the seed to the depth of its diameter. But, following planting depth recommendations on the seed packet is a better practice. All seedlings emerge from the soil with the shoot curled over as it pushes through the soil. This is nature’s provision for protecting the precious growing tip. The more delicate the seedling, the shorter the distance it should be forced to travel to the surface.
· After planting, pat, don’t pack, soil over the seed. This will allow oxygen to permeate the microscopic spaces in the soil and reach the softened seed coat.
Some plant species have special requirements beyond water, temperature and oxygen to break dormancy and begin germination. Practices such as stratification, scarification or pre-sprouting may be needed. Again, read and follow the seed packet instructions carefully.
Down and Dirty with Your Soil
This year, 2015, is the United Nations International Year of the Soil. The first 2015 edition of “Down to Earth” stated that matters of the soil would be a recurring theme throughout this year. Now that many gardeners and growers have gotten their hands back into their “black gold,” maybe it’s time to review some common sense ways to treat our parcel of this precious resource beneath our feet.
You might be expecting advice to get your soil tested. That advice never goes out of style and can frequently shed important light on the topic. It’s a simple process, inexpensive, and comes with good directions and supplies from ISU Extension. However, the Cliff Notes version of soil science cannot be reduced to a mere 3 letters and the nutrients they each stand for: N (nitrogen), P (phosphate), and K (potassium).
Following are some additional suggestions about how to work WITH soil intelligently. The goal in a perfect world is to grow your “crop” while avoiding harm or waste to a finite resource, our soil. While these suggestions may challenge us, they are worth operating within at every opportunity.
· Avoid tillage as much as possible. Seriously! The biologically active layer of soil just beneath the surface is an intricately interconnected community of air pockets, water, humus, sand, rock, clay, bacteria, fungi, roots, animals and plants. Repeatedly disrupting these myriad connections reduces the efficiency of the soil.
· Keep it covered. All year! Using an undisturbed grassland or woodland community as an example, you’ll note that the soil surface is covered with a layer of decaying vegetable matter. Maintaining a protective covering on the soil is one way to avoid harm or waste. The same covering also feeds the soil continuously. So, mulch, use mass rather than row planting, use cover crops, and leave plant debris on the soil after harvest.
· Keep toxins out of the soil. When reduced to this clear statement, it seems to defy logic that anyone would put toxins in the soil. Most of us, however, apply toxins to the soil, often many times during a year. As stewards of our parcel of soil, we have choices to make about what we apply to our soil and why. We must weigh the consequences as we decide how much weediness we’ll tolerate, whether we can stand a mole hill, how we maintain fertility, and how hard we’re willing to work at getting mismatched plant-to-soil combinations to produce.
Avoid compaction. Healthy soil is intended to resemble a sponge more than a brick. It follows, then, that driving or walking on productive soil decreases its efficiency. Here’s another good reason to park the lawnmower. Also a good reason for strategically placing stepping stones on a necessary path through a productive area.
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