Garden Microclimates - What You Need to Know

If you spend much time in your garden, you know where the wind blows the hardest during a storm, where the sheltered areas are and where the soil tends to stay boggy or dry. Those choice or challenging spots are part of the ecosystem that is your landscape. The more you know about how your garden functions, the better equipped you'll be to grow the plants you REALLY want to cultivate.

Plant Hardiness Zones and Your Garden

Most gardeners rely on the Plant Hardiness Zones published by the U.S. Department of Agriculture (USDA) to help guide their plant choices. Zone recommendations are published on seed packets, added to those plastic seedling spikes included with new plants and referred to in articles like those posted here. I think hardiness zones are somewhat misunderstood, though. Here's why:

Many gardeners believe zone listings include more information than they actually do. Those numbers aren't the result of complex algorithms of multiple geographical and weather related characteristics. Zone designations refer to the average anticipated low temperature for a specific geographical location. That's it. Here's how the USDA puts it:

"Hardiness zones are based on the average annual extreme minimum temperature during a 30-year period in the past, not the lowest temperature that has ever occurred in the past or might occur in the future." (USDA Agricultural Research Service)

Zones don't take into account heat, humidity, or microclimate variables like proximity to water or buildings. These last two are particularly significant because they can have a big impact on temperature but are too localized to be evaluated by zone, even with the more specific "a" and "b" zone designations in use today. (More on that in a minute.)

Here's an example: You have a pond, creek or other water source near your home. Wind coming from that direction will be somewhat cooler that the surrounding air because soil, which is dense, holds heat better than water. As hotter air passes over a volume of water, its temperature drops. The reverse is also true: Developed areas with lots of concrete roadways and tall buildings will hold heat better than the surrounding undeveloped terrain.
Protected areas can be warmer in winter.

This is even the case on a smaller scale:

In summer, the shady side of your home will be cooler that the sunny side.

Elevated areas like decks and balconies will be cooler.

In winter, unprotected locations will be colder than sheltered areas.

If you live at the base of a hill or in a dale, your microclimate will likely be colder than the surrounding terrain because cold air is heavier than warmer air and will migrate to the lowest level it can reach.

If your home is on a south facing slope, your yard will be somewhat warmer that the folks on the other side of the hill with a northward facing garden.

These microclimates create conditions the savvy gardener can take advantage of -- or prepare for.

Test Your Garden -- It's the Only Way to Be Sure

So, if you think parts of your garden are warmer or colder than the norm, grab a thermometer and do some research. The difference between zones is actually 10 degree Fahrenheit for an average winter low. That number is further broken down by an "a" or "b" designation, an incremental difference of 5 degrees Fahrenheit.

In English, that means you can look at a zone map, discover you're in Zone 5b and be 5 degrees Fahrenheit away from a Zone 6 designation. Natural microclimates in portions of your yard or geographical area could easily adjust for the 5 degrees and open up a whole new world of plants for you. You may find you have a sheltered spot where rosemary will thrive, or a chilly corner with asparagus potential.

Proximity to water can affect climate.

Here are some tips on how to take advantage of microclimate variations:

Watch your garden this year. Take a look at where the sun shines in the morning and afternoon. Pay attention to how the wind blows. Review  topographical maps. Your findings should factor into your garden planning. 

You can Install the Google Earth to take a look at 3D maps for your area. The software/service is free. The installation page is here: Google Earth

You can also visit the U.S. Geological Survey site for access to maps for your area.  Start Here: USGS Map Locator & Downloader  

Invest in some outdoor weather temperature equipment and start making notes during hot summer days and cold winter nights. Focus on areas you think may be average, protected or particularly vulnerable.

This can be a more reasonable investment than you think. There are reasonably priced wireless weather stations that allow for up to three independent outdoor sensors. A system will include a convenient indoor console with a summary readout. (*Outdoor sensors are typically pretty durable. They run on batteries and have weatherproof cases.) Perform a web search on "wireless garden thermometers" for options. I know that La Crosse Technology (WS-9160U-IT Digital Thermometer) has one, but there are definitely others.

You can also use the old fashioned method, and position an outdoor thermometer where you want it and check the readout during peak hot and cold periods. (This may take some garden love when you're slogging through the snow in the middle of the night, though.)

Once you have a rough grid of your garden's microclimates, you can start investing in perennial plants with a real sense of what you can expect from them. You may be surprised at what you discover.

Happy gardening.

*Based on product reviews, these batteries can last up to a year.


Cornell University Gardening Resources, "Microclimates" (06/14/2013)


Watering Herbs in Pots

Although many herbs are hearty and pretty indestructible, they do need water -- and regular watering will help them perform better -- whether you're after leaves, seeds or flowers. If you're maintaining a patio or deck garden, I have a few tips that can help your dainty darlings survive the summer weather.

Get thee to the fridge -- This first one seems a bit unusual, but it works for me indoors and out. I read about it in an old newspaper article about keeping poinsettias. These classic Christmas flowers are thirsty devils, and to maintain them well takes regular watering. One wily gardener came up with the idea of "watering" his poinsettias with a couple of ice cubes a day combined with once weekly deep watering. As the cubes melted, they dispensed water in a gentle and reliable trickle the plants could absorb easily.

This is really an inspired idea. Here's why: When a plant's pot gets too dry, the soil becomes less able to retain moisture. Water -- when it does come -- just rushes through and exits from the bottom. Without enough dwell time, plant roots can't absorb nutrients effectively and go hungry. The plant begins to look needy, which can lead to a vicious cycle of overwatering. The result: the plant either dies of starvation from lack of water, or dies of starvation because its roots are sitting in too much water and rot.

The beauty of ice is that it's a cheap, natural and effective method of timed water delivery. I've been using it for years on many kinds of indoor and patio herbs as well as other plants and can say from experience this method works on tropical plants like orchids, African violets, spider plant, pothos and other popular houseplants. It also works on chives, parsley, oregano, ginger, lemon balm, mint, thyme, lemon eucalyptus, pineapple sage and other herbs.

I'll typically add four ice cubes to each six inch pot in the morning before things start to warm up, and repeat the process again in the evening. During hot summer months like July and August, I'll also water plants in the evening as needed -- usually a couple of times a week. For a large plant in, say, a 10 inch pot, I'll just shake six or eight ice cubes from a carafe.

Although I haven't had problems, I'm careful to keep ice cubes away from plant stems and leaves, positioning them on the soil or mulch. I haven't used this method with cactus plants, but it does work with immature aloe vera starts and jade plant.

If the prospect of micromanaging your greenery isn't appealing, using ice cubes is one of those "set it and forget it" activities you can perform before going to work in the morning, making it a regular routine. The amount of water in an ice cube may not seem significant, but more moisture will be absorbed by the plant than with conventional watering, so it provides decent coverage without the risk of over watering and killing plants -- or damaging your furniture if your plants are indoors.

Mulch more
- Adding mulch to a potted plant is like providing insulation to a home. It helps in temperature control and impedes evaporation. I like adding moss, but also use sand, stones and marbles. Outdoors I've even used shredded paper anchored with rocks. Works great. (It's also another way to get full value from that paper shredder. If you don't like the look of newsprint, try shredding paper bags.)

Pick a pot (no, not any pot!) - Self watering pots, thicker walled pots and non-terra cotta pots help conserve water. If you have a thirsty herb like catnip, basil, cilantro or dill, plant it properly in spring and you'll have fewer water related problems later. Oh, terra cotta pots that have been sealed on the inside work fine; unsealed pots absorb moisture, stealing it from the soil in dry weather.

Rube Goldberg devices - Upending a two-liter bottle (or burying one in the soil), as a water resource for a potted plant can work pretty well. I've done it myself, especially when I plan to be away from home for more than a day during hot weather. There are plenty of DIY tutorials around that can show you how to turn a plastic bottle into a garden reservoir. Watering Plants on Hot Summer Days

Shade is where you find it - Plants in dapples light typically require less frequent watering on hot days than plants in full sun. Planning some shade strategies now, like placing taller and more drought tolerant herbs on the sunny side of your patio to screen smaller, more delicate specimens, can make August easier on you and your plants. I've been known to move pots around to make the best use of sun and shade. I've even tented plants with shade fabric and bamboo screening. Just because you placed a tub of geraniums next to the Adirondack chair --where it does look neat -- doesn't mean your blooms have to stay in that spot forever. If you're dealing with a large pot, consider placing it on coasters to make moving day easier on your back.


10 Unique Herbs to Add to Your Garden this Year

Tea Camellia

If you like growing herbs, chances are you already have a nice sage specimen or patch of mint on your property somewhere. You probably also have a little thyme plant, a bit of oregano, some parsley, a skoch of chives and a few basil plants rounding out your collection. There may be a rosemary shrub in your life -- lucky you. We herb lovers adore the classics, but there are still lots of worthy herbs that never seem to get into the popular lists for one reason or another. Let's take a look at 10 herbs that deserve a second look -- and maybe a bit of real estate to thrive in.

Unique Herbs to Add to Your Garden

1) Tea camellia - This camellia is relatively easy to grow in mild climates, and can even be cultivated as a house plant. It's the original plant grown for tea in the orient. Want green tea? Grow your own. Look for Camellia sinensis.
Saffron Crocus

2) Fall crocus - You know about spring crocus, the early bloomer that sends up spring shoots when there's still snow on the ground. A fall growing variety has the remarkable distinction of producing the most expensive spice on earth: saffron. You can also grow the saffron crocus indoors.

3) Soapwort - So, you want to be green in the laundry room but even those homemade soap recipes use caustic ingredients. What can you do? Grow soapwort as a mild laundry detergent substitute. It produces a nice lather that loosens dirt without the harsh chemicals.

4) Scented geranium - Those lush, large geranium flowers you love to grow every summer are just the tip of the iceberg. There are dozens if not hundreds of geranium varieties, many of which produce exotic scents and delicate flowers. These little plants are easy to care for and very beguiling.
Scented Geranium

Evening Primrose
5) Evening primrose - Yes, some beautiful and useful herbs do grow in the shade. Evening primrose is a lovely little example. It's been used as an herbal remedy to treat everything from asthma to PMS. Some other good shade candidates are ginger, tarragon and sweet woodruff.


6) Valerian - If you want a good night's sleep, valerian can help. Valerian root is considered one of the best herbal sleep aids available, and it happens to be easy to grow. Although the root is considered the most potent part of the plant, even the leaves can produce a relaxing tea. Other sleep inducing herbs that can be grown in the shade include lemon balm and chamomile.

Paprika Pepper
7) Paprika - Although this spice made from a pepper plant is very popular in Europe, it doesn't have the following it deserves in the U.S. Here's an example: Paprika may be colorful on deviled eggs, but it releases its wonderfully complex flavor best when heated. Grow your own peppers and see. Paprika is as easy to grow as jalapenos -- without the intense heat. It's also easy to dry and even smoke.

8) Ginger - If you have a shady spot in your temperate garden, with soil that isn't obstructed by shallow tree roots, you too can grow ginger. This hot-sweet root spice is attractive in the garden and useful in cooking. It's also one of the best herbal teas for stomach upsets. After harvesting, store ginger root indefinitely in a jar filled with Sherry. (This also works with store bought ginger.) Speaking of which: You can start store bought ginger in a pot or in the garden. Now, how's that for simple. 

Bay Leaf
9) Bay leaf - Bay leaf comes from the bay laurel tree, a Mediterranean transplant that can grow to 40 feet high. Bay can be cultivated as a house or patio plant, but it may take a couple of attempts to find accommodations this popular herb demands.

10) Stevia - Yes, you can grow your own sweetener in the garden, and it doesn't take a lot of space to do it. Once you have a few thriving plants, create a syrup to use in beverages and recipes. It's fun to do.


Photo Credits

Camellia - By Pancrat (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (

Saffron crocus - By Photographer: User:Velela (File:Safrron stigmas crocus sativa.JPG) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Soapwort - By Karelj (Own work) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Scented geranium - By Captain-tucker (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons'Fair_Ellen'_in_NH.jpg

Evening Primrose - By Dr. Thomas G. Barnes, U.S. Fish and Wildlife Service [Public domain], via Wikimedia Commons

Valerian - By Christian Hummert (Ixitixel) (eigenes Foro) [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons

Ginger - By Venkatx5 (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons

Bay leaf - By Gary Houston Ghouston 16:40, 2 Jun 2005 (UTC) (Own work) [CC0], via Wikimedia Commons

Stevia - jpg By Gabriela F. Ruellan (Own work) [CC0], via Wikimedia Commons


Getting Started in the Garden this Season

Here are some timely tips for getting started in the garden this year. Some are recycled, but they're pretty useful nonetheless:

What do you plan to snip and start - Take a look around the garden, and make a list of plants from which to harvest spring cuttings. In year's past I've been so busy in the garden I've forgotten about taking cuttings. If I'd had a note on the fridge with my wish list, there'd be more azaleas (rhododendrons and hydrangeas) in my front yard today. When you do get around to taking cuttings, forget the rooting compound. Use cinnamon instead. It works great for me.

Should you test your soil (yes) - While you're gathering up dead wood and getting your landscape in order, take the time to have a soil test done, or do one yourself. Knowing is better than guessing. I wrote a previous post about traditional and low cost testing options: How to Test Your Soil 

Save those seeds - If you plant from seed, it doesn't take long to accumulate a stash. Some (but not all) of those seeds will be viable. Although fragile specimens like stevia will lose viability quickly, fun and hardy herbs like basil can stay viable for a number of seasons.

Seed sprouts on paper toweling
I have two recommendations here: 1) Instead of wasting a lot of potting soil on seeds that won't germinate, start questionable seeds between sheets of moist paper toweling with cellophane on top to hold in moisture. Transplant sprouted seeds with the help of a pair of craft tweezers. 2) Check this list for a better idea of which herbs have the best chance of performing: Seed Longevity List

Rate herbs by project - The herbs you plant in the next couple of months will have a big impact on the types of projects you'll be able to complete this summer and fall. Choosing wish list projects today will help you decide of you'd prefer lavender (to make wands and sachets) or a stand of relaxing of sleepy time herbs for soothing teas (passionflower, valerian, lemon balm, catnip and chamomile). A large rosemary harvest will make for great culinary wreaths, while aloe vera is a convenient and effective first aid herb for minor burns and bug bites.

You probably can't keep every plant on your list, but knowing that you absolutely want to make your own stevia syrup (or chive flower vinegar) will certainly get you started.

Plant back to front - I can't tell you how many times I've wanted to rearrange plants after they were happily in the ground. One of the biggest mistakes I made as a beginning herb gardener was to midjudge how tall a plant would grow. This put me in the unhappy position of having small herbs behind taller ones. This often blocked sunlight to smaller specimens and made them harder to maintain (and enjoy).

Check the recommendations for the herb seeds and plants you purchase. They're published on the backs of seed packets and definitely worth the printing costs. You can also perform a general web search on the herb's scientific name. There are thousands of cultivars out there that require slightly different growing conditions. Make a small template showing where you want to plant your herbs based on their: height, spread, sun, water and soil requirements.

Think micro-climate - Every garden is made up of micro-climates that provide slightly different accommodations for plants. Taking advantage of the extra water by a downspout, a slightly warmer temperature near a sheltering wall or less wind by a back fence could make a big difference to a plant that's marginal for your area. Just take a little extra time to plan your placements. You'll be glad you did.  

Start preparing for bug patrol now - Start eliminating the threat of insect attack before June rolls around and you're elbow deep in Japanese beetles, earwigs and aphids. Preemptive measures include companion planting, choosing plant varieties that are naturally insect resistant and adding weapons like nematodes, milky spore, beneficial insects (like lady bugs) or traps to your landscape:

Companion Planting Herbs
What You Need to Know About Getting Rid of Japanese Beetles
Battling Earwigs in the Garden
Save your scraps - Even if you don't keep a compost bin, you can still take advantage of kitchen bounty in the garden. I mentioned this in an Odds-and-Ends post last spring, but it bears repeating. The following kitchen scraps will enhance the soil in your garden. Some gardeners add these amendments to their planting holes and then cover them with an inch of earth before adding the plants. As the ingredients decompose, they release nutrients into the soil, making them available to plant roots. It isn't a good idea to overdo it, but I've used all these in small amounts for specific plants:

  • Banana peels - potassium (blended into a slurry and added to a newly dug hole)
  • Egg shells - calcium (ground up in a coffee grinder)
  • Coffee grounds - nitrogen
  • Hardwood ash - calcium and lime (for more alkaline soil)
  • Epsom salt - magnesium (dissolve and sprayed on plants - 2 tbsp. to a gallon of water every couple of weeks)

That's it for helpful hints this week.

Japanese Beetle Photo - JapaneseBeetlesWiki.jpg By D. Gordon E. Robertson (Own work) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons


The Best Drought Tolerant Herbs for Your Summer Garden

Lambs Ears
Planting drought tolerant herbs can make life easier in the garden. If you live in an arid location, even intermittently, choosing water loving plants for your garden means extra work and expense -- or a big disappointment somewhere down the road.

Hot, dry conditions stress plants and cause problems a number of ways:

  • The soil becomes compacted.
  • After a few seasons, cracked, dry soil can lose essential nutrients necessary for good plant growth.
  • Hot winds may send plants into a sudden decline.
  • What moisture does fall may come as big cloudbursts where water rushes into gutters and storm drains before it has a chance to soak into the soil.

The whole thing can be a meteorological, botanical and budgetary guessing game. So, is this going to be a good year or a lousy one for rain and predictable weather?

One way to hedge your bets in the herb patch (and out) is to plant a nice sampling of relatively drought tolerant specimens. This is easier than you might think. Herbs are nature's "make do" plants. They are often considered weeds in their native habitats, which makes them tough, resilient and enduring. Although most plants NOT grown for desert habitats require a reliable source of water, the herbs on this list are pretty hardy. Many are native to the Mediterranean, a spot that can get and stay  dry in summer.

Short List of Drought Tolerant Herbs

Sage - although Russian sage is often promoted as a drought tolerant plant, which it is, Perovskia
atriplicifolia doesn't have the culinary reputation of classic salvia sage varieties like garden sage. By most accounts, though, it is edible. Both Russian sage and Mexican sage (S. mexicana) are primarily ornamentals that can help create a green space in a hot summer garden and even provide shade for shorter, less drought tolerant herbs. Both can grow from 3 to 5 feet in height and spread almost as wide, with spiky purple flowers reminiscent of "cottage garden" sage.

Garden sage (Salvia officinalis) is also somewhat drought resistant. Steer clear of pineapple sage and a few other specialty varieties unless you plan to keep them near a downspout or close to the garden hose. One other warning: Although garden sage and some of the colorful varieties like tri-colored and yellow sage can take some punishment, when they do begin to droop, it's hard to bring them back from it.

Thyme - It may seem counterintuitive, but little garden thyme (Thymus vulgaris) is scrappy. This plant can survive drought conditions and heat, even though its tiny leaves look delicate and vulnerable. Remember, this herb is native to the Mediterranean, so it knows its way around hot
summer afternoons.

Lavender - The lavenders are typically drought tolerant, but some fair better in humid conditions than others. There are also lots of cultivars available these days; you'll likely find one that suits your garden and your culinary or crafting plans. If you're in an area with four distinctive seasons a year, prefer varieties that can withstand cold as well as heat. English lavender is one, but there are

Chives - This onion relative is surprisingly drought, cold and humidity-proof. Its lavender flowers are charming in spring, and it's handy in the kitchen, too. This one never lets me down.

Artemisia – A large group of shrubs and bushes, the artemisias can look, smell and grow quite differently from one another, and have different characteristics to recommend them. Artemisias are often hardy and can have attractive feathery or silvery foliage. The herb bitter wormwood (Artemisia absinthium L.) is a type of artemisia used as a digestive aid and in bitters. Silver mound is an example of an artemisia cultivar (Artemisia schmidtiana) with good drought tolerance. There are others, too.

Lambs ears - Wooly Lambs ears (Stachys byzantina) has few herbal uses these days, but once it was considered a great wound dressing. Today it's used primarily as a landscape plant. It's quite lovely,  with fuzzy leaves and lavender stalks that can reach 18 inches high or a bit more if it's happy. It fills in so well it can become a bit of a pest. Children love it, though.
Flat Leaf Parsley

Flat leaf (Italian) Parsley
- Plants with long taproots, like flat leaf parsley (Petroselinum crispum var. neapolitanum) fare well in dry conditions. Their long, thick roots retain moisture and nutrients when the going gets tough. As a rule of thumb, if a plant has a long taproot, it's less likely to be a drought casualty. Flat leaf parsley is the preferred parsley variety for cooking, too. Fennel is another example of a drought tolerant herb with a long taproot.

Here are some other  drought tolerant herb candidates that deserve an honorable mention: rosemary (Rosemarinus officinalis), Greek oregano (Origanum spp.) and Yarrow, (Achillea filipendulina).

Tips for Dealing with Drought Conditions

Before we get to the list, though, here are a few tips for making the most of what water nature does have on offer:

Afternoon shade - When conditions get hot and dry, plants that would otherwise thrive in full sun may need afternoon shade. In anticipation of a dry year, plan to offer plants some shade (or dappled light) during the hottest part of the day. Moveable screens or fences, tall screening plants and shade netting can help.

Mulching - Providing moisture for plants is only part of the challenge, the rest involves getting that moisture were it needs to go (to plant roots) before it evaporates or runs off. Mulching can help. A layer of almost any mulch product will help increase moisture retention in the soil around plants. Mulching will help potted plants retain water, too.

Smart watering - When water is scarce, every drop is precious. Watering methods like drip irrigation make the most efficient use of any water you have to share with your green growing things. These systems can be pretty cost effective and will save you money on your utility bill over time.

If you have to stick with supplementing water with your garden hose, avoid watering during the hottest part of the day. Prefer morning or evening watering. I like morning duty because it's less likely to contribute to plant problems like powdery mildew. Another option is to install a rain barrel and use the harvested water on your ornamental plants. (Harvested water may not be wholesome for plants you plan to use for culinary or medicinal purposes.)

Fill your beds - I like keeping my flower beds, herb and vegetable patches fully stocked. Although more plants means a higher water demand, the presence of all that greenery helps create a more humid, thriving microclimate and favorable growing conditions. This doesn't mean you should crowd specimens. Just create a healthy community of plants instead of leaving big, open spaces between plantings.

Plant commuters - This is more work, but you can always plant favorite specimens in self-watering pots filled with moisture control potting soil. Move the pots around your deck, patio, balcony or even flowerbed as needed. A spot that's perfect in May could be brutal by August. Moving plants to a shadier location could keep them healthy for the duration. In fall, plant the pot in a flowerbed for safekeeping outdoors, or bring it inside.

Feast or famine - Drought tolerant plants are superstars at surviving with less water. They may be somewhat more persnickety about dealing with an over-abundance of water, though. This can happen in heavy, clay soil that tends to stay soggy after a rain. You'd think that extra moisture would be welcome, but the roots of these plants are often ill suited for soggy conditions and unable to handle being waterlogged. The roots die off, and without healthy roots to take in water and nutrients, the plants starve.

For the best results, take care to provide drought tolerant plants with soil that drains well. If you're dealing with clay, consider adding organic amendments like compost and leaf mold to lighten and loosen the soil. To do the job right, have your soil tested if you haven't already. After a few years of preliminary prep in spring, your landscape will be rich, loamy and the envy of the neighborhood.


Sage Photo - Salvia_officinalis.jpg By Takkk (Own work) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Lamb's Ears Photo - LambsEars3_Wiki.jpg By Stan Shebs GNU Free Documentation License, Version 1.2