Rock Garden FAQS

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Rock Gardens

What is a Rock Garden?

The typical rock garden has fast-draining, rocky or sandy soil that is low in organic nutrients and plants in this group thrive in this situation.  Rock garden plants are generally small scale and compact plants that are suitable for growing in a naturalistic, rock accented garden.

Rock Garden Plants

Where can rock garden plants be grown?

  • Large or Small-scale Rock Gardens
  • Woodland Gardens
  • Troughs
  • Raised Beds and Planters
  • Native Gardens
  • Containers and Hanging Baskets
  • Waterside Gardens
  • Along Paths and Steps
  • Other Compact Spaces

The Role of Rocks

What is the role of rocks in the rock garden?

Rocks play an important role in the growth and health of many plants just as they do in their natural habitat.  Rocks affect the immediate environment in a number of ways to allow the plants to flourish: 

  • Rocks shelter seeds, allowing them to lodge and germinate,
  • Runoff from rocks provides supplemental water and nutrients that help the plant become established, 
  • Shade from rocks keeps the soil around the plant from drying out and protects the plant's roots from heat from the sun, 
  • Rocks also provide a protected, competition-free location in which the plant can thrive. 

Alpine Plants

What is an Alpine Plant?

Alpine plants or alpines are generally considered plants from high mountain regions of the world but also include other small scale plants. They can be used in alpine gardens, rock gardens, troughs and containers and many are suitable for crevices and rock wall plantings. Because of their small scale, it is important to group them with other small scale plants so they are not overrun by larger plants.

Alpine Frames

What is an Alpine Frame?

An alpine frame is a well-ventilated structure used to protect plants from weather extremes and in particular from winter wet.  It is essentially a greenhouse, cold frame or other growing structure that is modified to create excellent air circulation and low humidity growing conditions.  Individual plants may be plunged into sandbeds, further moderating temperatures and keeping plants evenly moist.

Fertilizer and Watering Needs

Do alpine and rock gardens have special fertilizer and watering needs?

Rock garden plants and alpines often require little fertilizer and those from sunny, dry climates need very little supplemental water. 

Many plants from Mediterrenean climates require little water or fertilizer.  Lavenders, thymes and other aromatic herbs originated in rocky, infertile hillsides of the Mediterrenean region where summer rainfall is minimal and they are quite drought tolerant.  These plants and other plants from similar climates are often used in a low water garden. 

High mountain plants often require low levels of fertilizer and some are low water, too.  These plants, known as alpines, are classic examples of rock garden plants that thrive in austere settings where the soils contain very few nutrients. In cultivation, these plants require little fertilizer.  Their water requirements vary depending on factors such as how deeply their roots system extends and whether they grow in a relatively dry environment such as on a mountain peak or in a wetter area such as in a meadow. 

Improving Drainage

How do I improve drainage?

Many plants require excellent drainage for healthy growth.   Plants are often grown on a slope or in a raised or mounded bed where irrigation or rainwater flows quickly away from plant crowns and roots. 

Drainage can be enhanced by adding a combination of rock chips or grit of 3/8 " or less and coarse sand to your soil. We use 1/4"-10 gravel which has fewer fines that cause compaction.  The addition of these large and uneven particles enhance drainage.  The amount of amendments needed varies with your soil type.  The goal is fast drainage and easily workable soil..

A rock chip mulch is generally used in the rock garden.  This type of mulch allows water to drain quickly away from the crown of the plant, allowing the crown to dry quickly and reducing the risk of disease. 

Raised beds can be filled with a mixture of sand, gravel and compost or bark dust to create a low fertility mix for growing alpines.  We have used a combination of equal parts sand and gravel along with 10-30% compost for our raised beds with good results.

Troughs and Containers

Alpine Troughs and Containers

Troughs and containers of all sizes and shapes are commonly used by alpine gardeners because they are an excellent way to showcase small scale plants.  Factors such as soil drainage and fertility, light and heat exposure and moisture needs can be more easily monitored and controlled in a container than in the open garden.  Troughs and containers can also be moved to a sheltered location during winter to protect plants sensitive to excessive winter moisture such as alpines, bulbous plants and other perennials from dry winter regions.

Growing in Scree

What is Scree?

Scree is a loose, very rocky and low nutrient soil substitute that can be used to provide exceptional drainage and a deep root run to alpine and other difficult to grow plants.  A typical scree mixture would combine sand for moisture retention with small crushed rock to create a low fertility, open growing matrix.  Scree mixes can be used in containers, raised beds or the open garden to provide a healthy growing environment for plants that do not thrive in ordinary garden soil.

Tufa

What is Tufa?

Lime tolerant plants can be grown in and around tufa, a porous calcium carbonate-based rock prized by alpine enthusiasts.  In this low nutrient environment, alpines are slow growing and maintain a tight, compact form.  Water sensitive plants can be inserted vertically into the rock or even under overhangs where they are shielded from the elements.  

At the same time that tufa helps alpines avoid excessive moisture on the foliage and crown, the tufa itself absorbs and holds water like a sponge.  Water is released slowly over time allowing plants to remain evenly moist and cooled by the slow, steady evaporation and preventing heat stress at the root zone.

Common Names

Why can't I find the plant I'm looking for using the Common Name?

We can't help commenting on the difficulties in using common names to identify plants.  For one thing, many of the plants we grow do not have common names.  Other plants have more than one common name which can lead to great confusion.   A familiar example is the use of both Black-eyed Susan and Gloriosa Daisy to refer to Rudbeckia hirta.  

To make things even more complicated, different plants can have the same common name.  Take, for example, the customer who requests "Rock Cress" or "Dusty Miller".  Does she mean Arabis or AubrietaArtemesia or Senecio?  There are regional differences, too.    The term "Bluebell" refers to Campanula rotundifolia in Scotland, Endymion nonscriptus in Endland, and Phacelia campanilaria in the Western U.S.  It is easy to see that the use of botanical names is a far more precise way to find exactly the plant you seek. 

It can be intimidating to try to say complicated botanical names but we tell our customers not to worry about pronunciation.  There is no one right way to pronounce these tongue twisters and we would rather you try so we can help you find the right plant.  It might be some comfort to learn that the way a plant name is pronounced varies widely from place to place.  We sometimes amuse ourselves by going on "how do I pronounce" websites and listen to the pronunciation of plant names in different regions of the world.  Don't let the plant snobs intimidate you.  Just say it!



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