Microclimates and Other Weather Effects

Microclimates are something that every garden has.  Microclimates are areas of your yard where the temperature is affected by the landscape. This includes the grade/elevation, any prevailing winds and wind speeds, the presence/absence of standing water, etc.  

Growing Plants and Elevationhills

Hills are more exposed than other microclimates. These microclimates are generally colder than flat surfaces. Ravines or dells are more insulated, so they can be warmer on average than either of the previous situations.  So if you are in a Zone 4 climate, your hilltops may be on the colder end.  Any ravines or dells may be more sheltered, and you may be able to experiment with more Zone 4A or even Zone 5 plants there.  Keep in mind experimenting with higher zone plants has the possibility of failure.

Wind’s Impact on Growing Plants

Knowing your prevailing winds and their average speeds can help you plan the microclimates your garden for success.  South and West winds are generally going to be warmer than North and weathervaneship12East winds, for example.  

Faster wind speeds will have a cooling and drying effect on areas experiencing them, as the wind pulls water out of the plants through evaporation.  The point at which damage occurs can be hard to predict, since different plants can take more or less wind.  If you can notice a significant wind coming through pretty steadily, please take it into consideration when you are doing your planting.

For example, if you have a corner of your garden with a prevailing Northeast wind, and a noticeably brisk speed, you will have a significantly cooler climate there.  If you have an area with a strong Southwest wind, you may have a very hot and dry area to plant!  

You can try to soften the blows by planting in masses and using larger shrubs and woody


Diagram of Appropriate Windbreak Design (worldofagroforestry.org)

perennials as windbreaks.  By forcing the winds through other, stronger plants, you can mitigate the speed and to some extent (not 100%) the direction, as having a large planting insulates significantly and can keep more moisture to itself than an isolated single plant, surrounded by hot or cold air.


Standing Water and Its Effects on Microclimates

gardenpondStanding surface water can have a significant impact on your garden’s temperature.  Any presence of standing surface water has a cooling effect in summer, since water is constantly evaporating into the atmosphere.  It also has an insulating effect, keeping temperatures more stable and moderate, and less prone to spiking with heat or cold.  These areas may take longer to warm up in spring and cool down in fall.  The effects vary with the size of the body of water, so expect small buffering from smaller ponds (and possibly still temperature spikes), and a larger ‘calming’ effect from larger ponds or small lakes.  

If you live near a large enough body of wlakeater (like a very large lake or even ocean) you may also see significantly more snow, due to what is called the ‘Lake Effect’.  Since plants see snow as a great insulator against winter temperatures. More snow is not usually a concern from the plants’ point of view – they don’t have to shovel!  

Snow weight might be concerning if you have delicate or new woody plants or trees, so be sure to watch any build-up carefully, and remove when it becomes too heavy to prevent limb breakage.

Climate Change and Global Warming Effect on Growing Plants



As our global climate changes, our growing zones have begun to shift as well.  The USDA is continuing to collect data and research, and updating the map as needed.  However, what’s becoming more common is temperature swings. So extreme and abnormal temperatures have been recorded more frequently.  

Cold Snaps and Heat waves are something gardeners must always be prepared for. That’s because the Hardiness Zone map does not take them into consideration. Winter mulch is recommended for any tender or newly-planted areas. Plants appreciate shade and water in extra hot summers.  Being prepared for extremes always increases survival rate. It’s hard to be able to predict whether or not you’ll need preparations. But it’s better to be prepared rather than sorry!  


Heucherella ‘Solar Eclipse’

If you have new plantings, remember to give them a little extra TLC, as mentioned in the previous paragraph.  Extra water, shade, mulch, and attention are all good ideas.  Baby plants need some, well, babying.  They haven’t stretched their thirsty roots out very far yet. and their leaves and crowns may be used to greenhouse conditions and not the ground freezing solid quite yet.  A little care goes a long way to set them up for future success!

What is a Growing Zone and How to find yours!

A Growing zone (also called Hardiness zones) are areas that determine what plants are likely to thrive in that locations. The average winter extreme low temperature is what the USDA uses to determine growing zones. This means the USDA has collected data from hundreds of research stations across the country to determine what the lowest average temperature is in each spot every year.  They then build or adjust the map of Hardiness Zones to illustrate what kinds of plants will survive the winter temperatures in each area.

This doesn’t take into consideration any abnormal extreme low temperatures. So sometimes there can be lower than average temperatures to watch out for.  Luckily, natural forces aside, the USDA Hardiness Zones map is usually very accurate. When used correctly, it can be one of the most useful tools you can use to determine which plants will grow and thrive in your garden, and survive your winters and/or summers!

Finding your Growing Zone

To see an interactive and more detailed map (including a zoom function and to search by zip code) please visit the USDA’s map website: here:http://planthardiness.ars.usda.gov/phzmweb/interactivemap.aspx

Here is the current USDA Plant Hardiness Zones Map, with half-steps.


To find your zone, look for your region, state, and approximate city area.  Then use the key to determine what zone the color represents.  That will be your Growing Zone.  For best results in your garden, only purchase and plants rated for your zone. Plants that do not mention your particular zone may not survive the average winter/summer temperatures in your area.  

Growing zones that plants are rated for are usually on their tags and/or online descriptions when they’re sold.  For example, if you are in Zone 4, and check a tag/description that says ‘Zones 4-8’, you can grow that plant! If the tag/description says ‘Zones 3-9’ you can grow that one, too!  If the tag/description does not cover your zone, it’s not a good idea to grow that plant in your garden.  We’ll talk more about that later.  

Marginal Growing Zone Areas

If you are in between zones near a zone boundary line, for example where zones 3 and 4 meet you may want to be extra careful with your plantings.  Being cautious and purchasing/planting for the lower-numbered (in the example’s case, zone 3) or colder zone is a good idea.  

If you’d like to plant for the higher-numbered (in the example’s case, 4)  or warmer zone, proceed with caution. Experiment with the knowledge that some of your plants might not ‘make it’ through the winter cold or may ‘die back’ in the summer heat.  

You can also utilize a winter mulch/covering to increase your chances of winter survival. You could also use extra shade/water in summer to increase your summer survival rate. But that may not make 100% of plants tolerant of the temperatures involved.

Growing Plants Out of Your Growing Zone

If you want to try growing a plant rated higher than your particular growing zone, you can also try winter mulch and summer shade/extra water. However, your plant has a good chance of not making it. For any plant grown out of its zone, that’s normal. There is nothing wrong with that plant. It just means the plant cannot survive a place to which it cannot adapt.

We cannot recommend growing perennial plants in zones they are not rated for.  If there is a plant you enjoy rated out of your growing range, consider planting it as an annual. Have the expectation it will die at the end of your growing season. But you can always replant it next year and enjoy again.

Growing Perennials as Annuals

Plenty of our customers have a great time growing their favorite perennials as annuals!  Most gardeners the world over have planted annuals to brighten up their yard for just one season (or replant every year). Annual plants fill out most container gardens!

When you think of how you use plants like geraniums, petunias, impatiens, and marigolds (to name a few popular annuals in our area), know you can also use perennials out of your growing zone that way as well!  Why not try some interesting perennials like penstemon, euphorbia, geum, and more in your containers and beds?

Remember, your plants will only have one season of growth. So they may not get to their full mature size, or have as profuse of blooms as they would if they had more years to accumulate growth. But the plants grown by you can still be enjoyed in the garden for what beauty they provide!

Can you grow Hostas, Heucheras, and other Perennials Indoors?

One of the questions people like to ask is if you can grow Hostas, Heucheras, and other Perennials indoors? The short answer to this question is, unfortunately, no.

The long answer is maybe, but it is very difficult. If you love a challenge, you can give it a try!

Hormonal Reasons

The main reason why it’s not a good idea to grow temperate perennials (perennials that need a seasonal temperature change, or a ‘winter’ period) indoors is that they absolutely require a cold, winter ‘rest’ period.  This primes them for their annual cycle of new growth in spring, summer filling out, fall die-back, and winter rest.  

The cells in plants secrete hormones that control their growth. Hormones also control how they grow, and when they grow. In addition, hormones are responsible for seasonal light and temperature changes that happens naturally outdoors in temperate perennials.

Basically, when you give temperate perennials a fairly unvarying temperature and light levels (like in indoors environments), their internal systems aren’t working quite right!  The symptoms include a lack of vigor or being excessively stretched, pale plant stems, and a slow decline to eventual plant death.

Environmental Reasons

They can also suffer from environmental stresses, due to the fact they’re in an unnatural environment.  We’ve created an ideal indoor environment for human beings – we have vents that blow out heat in winter, keep it chilly in summer, made our buildings air-tight and dry (no wind or humidity!) and have developed low glare, dim lighting in the spectrums that work best for the human eye.  These are, regrettably, very poor and confusing situations for temperate plants!  

Now for the challenge! You can almost certainly grow just about anything indoors, but you have to modify your growing space accordingly in order to do so

Requirements to Grow Temperate Perennials Indoors


The first requirement (and frequently most important for all indoor plants) is light.  Light is sunlitwindow1commonly measured in footcandles. It’s the amount of illumination the inside surface of a one foot radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. It is defined as the illuminance on a one-square foot surface in which there is a uniformly distributed flux of one lumen.

The average light level outdoors on a sunny day is around 1200 footcandles.  

In the shade, that drops to 350 footcandles.  

Inside a room with a window, about 200-800 footcandles (depending on how close to the window you are, the orientation of the window, direct sunlight, etc).  

Inside an interior office (no windows, overhead lighting) only 30 to 40 footcandles!  

A desk lamp only provides 30 to 80 footcandles, directly underneath!


Example of a light meter

To acquire as much light as possible, place your plant near a sunlit window.  Supplemental light is recommended as well as frequently required (especially for full-sun plants!).  

If you’d like to find out exactly how much light you have in any given area, you can buy a light meter on many hobby websites and Amazon (Professional Light Meter)


LED grow light

Plants need special light spectrums. While humans enjoy the full spectrum or close to it, plants on the other hand can only use certain sections of the spectrum (mostly red and blue) and require more of those.  Plant ‘grow lights’ are sold in many stores as well as online (here’s an example TaoTonics LED) – if you’re serious about growing plants indoors, it’s best to do your research and invest in a grow light if needed for best results!

Seasonal Temperatures


A selection of hostas in pots

The other most important requirement is seasonal temperature.  If you want to grow temperate perennials (like Hosta, Heuchera, anything grown outdoors in USDA growing zones 1 through 12) they will absolutely need a ‘winter’ cold period.  The cold period can be attained through many different ways, but it depends on the size of your plant and pot.  

For the largest plants and pots, the only options tend to be either leaving them outside (covered or insulated) or in your garage over winter (if you live in the plants’ growing zone).  Similarly, you can also test how cool your basement gets.  By chance it does get cool enough (check the plants’ requirements, and growing zone winter temperatures), place the pots there for a cooling period.  

hosta in round container

Hosta in small pot

If you live in an area where you have no winter cooling (or inadequate winter cooling for your choice of plant) I recommend sticking to smaller pots, or growing temperate plants indoors as annuals, and replacing them every spring.

For smaller plants and pots, you may be able to fit them in a fridge. To prevent drying out or excessive moisture, these plants will have to be carefully covered and checked frequently.  You can always follow the same instructions for large pots, and place small pots in basements, garages, or outdoors for winter as well.

If you are prepared to cater to your temperate perennials’ needs for light and temperature, the third requirement is water and humidity.


Indoor plants require much less frequent water than plants grown outdoors.  That’s because indoor plants do not transpire (water evaporation from leaves) as much as outdoor plants. That’s due to the fact they don’t have wind or breezes to ‘pull’ the moisture away.  Therefore, they also tend to grow at a slower rate, so they just don’t need as much water to drive their food production system.  This makes it easy to overwater indoor plants!  


Example of a digital soil probe

Make sure to always check the soil moisture levels before watering. This creates an idea of how often the plant truly needs to be watered. There are commercial ‘soil probes’ available to measure soil moisture by either electronic means or physically pulling a soil sample from lower in the pot. Here’s some examples of soil probes of the electronic variety (Dr. Meter)

and the physical variety


Example of a physical soil probe

(Alien Soil Probe).

Symptoms of overwatering include brown leaf tips, a funky smell to the potting mix, and stem or root rot.  Fungus gnats are hard to get rid of since they love overwatered plants. So if you hear small and irritating black flies buzzing around, that means no more water please!



Example of a plant mister

Some plants require more moisture in the air, rather than at the roots. These would benefit from a light misting daily or frequently.  You can purchase a squirter or sprayer bottles for these plants, and use as recommended for the plant family/variety. An example here (Coolrunner Vintage).

Potting Mix/Soil


First of all, ALWAYS plant indoor plants in a soilless media mix. Your local garden store should easily carry soilless media mix.  Garden or outdoor soil or dirt can frequently be problematic indoors, US-Miracle-Gro-Potting-Mix-75637300-Main-Lrgdue to the fact it can be contaminated with insect pests and diseases.  Soilless media is ph-balanced which makes the ph-balance is neutral. It has good large pores to store water or air for growth, as well as allowing easy root growth.  

Garden soil (your own or purchased in bags) can tend to either be clayey (can ‘bind’ nutrients, making them difficult/impossible to access), or ‘sandy’ (refuse to ‘hold on’ to any nutrients, letting them leach out of the pot entirely).  Similarly, it’s prone to compaction. Compaction makes it smaller for no pores for water or air which makes it unnecessarily difficult for roots to grow through.  Make sure you’ve purchased ‘soilless potting mix’ instead of bags labeled ‘garden soil’ or ‘potting soil’!  Indoors is already a hard environment, let’s make it easy on the roots!


Indoor Plant Alternatives

If temperate perennials sound like too much work indoors, there are other plants that are much more easily adaptable to indoor environments!  The Tropicals!  Stores often sell tropical plants as ‘indoor’ plants. That’s because their ideal habitat is quite close to our indoor environment!


One of the many varieties of Draceana

Tropical plants (like Dracaena, Pothos, Ficus, and other plants native to USDA growing zone 13) require constant, fairly warm temperatures, and plenty of moisture. Many plants are able to adapt for being in the shade(understory natives)! These plants have the best chance of surviving and even thriving in an indoor environment without significant modifications.  If you want to build yourself a lush, green indoor paradise, we recommend exploring these great families!


Here’s some links to articles with lists of easy-care tropical indoor plants!







(file:///C:/Users/Hostasdirect/Downloads/Lightlevels.pdf) (University of Denver, DU Portfolio – What do light levels really mean)