I have a shady backyard (mostly maple trees). Are there any ornamental grasses that will grow there?

There is quite a variety of ornamental grasses that will grow in the shade. Not as bold, big, tall and dramatic as the sun-loving ones, but certainly equally beautiful. They are easy-to-grow plants that fit nicely into the more serene and subtle nature of a shade garden. Some are tolerant of drought conditions, which you might have under your maple trees. For most it would be good to supply at least an inch of water per week. Here are some ornamental grasses that do well in the shady garden:

Hakone grass (Hakonechloa macra ‘Aureola’). This attractive grass is one of the best for shade. It has striking gold variegated leaves with an attractive habit of falling over to one side. This plant makes a lovely companion to hostas.

Palm sedge (Carex muskingumensis). This sedge spreads to create a low maintenance groundcover for moist, shady locations. The light green leaves resemble palm fronds at the top, which gives it its common name. Grows about 2 feet tall.

Bowles’ golden sedge (Carex elata ‘Aurea’ or ‘Bowles’ Golden’). Has attractive lime-green leaves in early spring and makes a lovely companion to gold variegated hostas. Grows 2 feet tall and prefers moist shade.

Silver variegated Japanese sedge (Carex morrowii ‘Variegata’). Has white leaf margins and grows 12 to 18 inches tall. It likes morning sun or part shade.

Variegated sedge (Carex morrowii ‘Ice Dance’). This semi-evergreen sedge has green foliage edged in pure white. One of the newer grasses for shade, it spreads to create a low-maintenance groundcover in the shade garden.

Plantain-leaved sedge (Carex plantaginea). Grows 6 to 12 inches tall and has green leaf blades that are wider than most sedges. Among the grasses for shade, this is one of the best for tolerating dry conditions. It makes a nice companion to ferns and North American woodland natives.

Northern sea oats (Chasmanthium latifolium). Grows about 3 feet tall. It has dark-green, bamboo-like foliage and attractive dangling flowers in mid-summer. This grass can take quite a bit of sun and sometimes can self-seed excessively, so remove flowers in late fall. (The flowers can be used in fall cut-flower arrangements.)

Snowy woodrush (Luzula nivea). A clump-former, it grows about 18 inches tall and is evergreen, with light green leaves and clustered white flowers in May to June.

Greater woodrush (Luzula sylvatica). This evergreen, clump-forming ornamental grass has green foliage covered with silky hairs. It grows about 2 feet tall and flowers in late spring into early summer. It prefers moisture and light to medium shade, but is quite drought tolerant. It is tolerant of most soils. Makes a good companion to ferns, shade-loving wildflowers and shrubs.

I see the term “frost-free date” used this time of year. What is the frost-free date for southeastern Michigan and what exactly does that mean?

Frost-free dates are a scientific best guess to determine when you will be able to plant out annuals or any other tender plant without the likelihood of those plants being killed by a frost. Michigan State University has published a table of dates based on a thirty-year average (1951 to 1980) that gardeners can use to determine these dates in their local community in Michigan. To use an example, the published dates for Pontiac’s 30-year average date of the last 32-degree temperature is May 24. This means that it is statistically safe to plant on or after May 24 in the Pontiac area and not experience a low temperature under 32 degrees.

This date is not a guarantee, only a statistical calculation based on historical data. Many gardeners choose to plant earlier and are able to protect their tender plants with coverings on any night when the weather is predicted to drop to near freezing or below. However, planting early is often unnecessary work, as plants placed into warmer soil with warmer night temperatures will grow with enough vigor to match the growth of the earlier transplants very quickly. The old adage, better safe than sorry, can also mean less work to produce the same vigorous plants.

If you would like the exact statistics for your community, visit the website at http://climate.geo.msu.edu/climate_maps.html and click the map on the spot nearest to your Michigan gardening location. Frost-free dates in southeastern Michigan vary by location. On the website you will also find a myriad of weather and climate information that may make your gardening easier, or at least more scientific.

According to a soil test, I need to lower the pH of my soil. What are the best and safest ways to do that in an area where I want to grow vegetables?

So you’ve decided on a spot for your garden and have an idea of what you want to grow. That’s a great beginning. Wisest of all, you’ve tested your soil, specifically its pH, so you know which plants will grow best in that bed. Most plants prefer a soil pH somewhere between 6.5 and 7.2. The term “pH” comes from the French term pouvoir d’hydrogene which means “hydrogen power.” It is the amount of hydrogen ion concentration in the soil sample that is measured on a scale from 0 to 14; zero being the most acidic, 7 neutral, and 14 the most alkaline. The pH scale is logarithmic, meaning that each number on the pH scale actually represents a tenfold change. For example, a pH of 7 is ten times more alkaline than a pH of 6.

You can lower your soil’s pH (making it more acidic) by adding chemicals such as soil sulfur, iron sulfate or aluminum sulfate, adding an acid-type fertilizer, or by working organic mulches into the soil such as peat moss, oak leaf mold, composted animal manures, sawdust, ground bark, decayed pine needles, or homemade compost among others.

Organic mulches are likely to be your safest pH-adjusting additives. They not only cover and protect the soil, they also release substances that feed earthworms and other helpful soil organisms. These organisms release nutrients into the soil so that plant roots can absorb them.