Twilight Zone? or Plant Hardiness Zones

 As I was going through my gardening books, I saw the Plant Hardiness Maps, and I recall that the Zone system for plants can be quite confusing for folks.

The Plant Hardiness Zones are numbered from 1 to 9, where 1 is the coldest climate, and 9 being the warmest.  It is not only the winter temperature which is considered in the assignment of Zone numbers.  Every factor that influences how well plants will grow is taken into consideration:  winter temperatures, length of frost-free growing season, quantity of precipitation, degree of humidity, and winds.  This results in general areas.  A plant that is hardy for Zone 1 can grow in higher zones.  But a plant that is hardy to Zone 6 will likely not survive in Zone 4 or lower.  Some plants need the winter dormancy for survival.

According to the maps, my area is Zone 2 (a or b), although we are safe to consider ourselves Zone 3.  The specific area where you live, e.g. high up on a wind-swept  unprotected hill, or conversely, a south-facing, well-sheltered flowerbed close to a heated building, may provide you with a unique microclimate, which would influence the plant choices for that spot.

My sister in Sherwood Park had a lovely, sheltered, south-facing yard—she grew all kinds of Zone 5 and Zone 6 plants successfully.  She was also fanatical about watering and mulching. One of our customers from Andrew (which is a zone 2 frost pocket) has also had good luck pushing the Zones in his sheltered yard.

You cannot assume that, if a greenhouse or nursery in this Zone sells certain plants, they are necessarily hardy for this area.  Always check the tags for the zone—they are generally fairly accurate.  Mail order seeds and plant catalogues generally do not give Zones. Some plants that are not winter-hardy in our Zone, are lovely plants if treated as annuals and enjoyed for only one season.  The best example I can think of here is that of Tea Roses.  With proper protection it is possible to winter tea roses, but probably only with 50% chance of success.  So, buy them if you love them, plant them in a large pot and enjoy them on your deck or patio, and just like your hanging baskets, let them go in the fall. We sell only hardy roses recommended for Zone 2 or 3.

Some shrubs which are “funny” with regards to Zone are Forsythias, Azaleas and Rhododendrons, to name just three.  These are listed as Zone 4 or 5.  The reality is, the plants will likely survive our winters with sufficient snow cover, but the flower buds are not hardy to Zone 3, so if they bloom at all, the blossoms will be only on those branches that were covered by snow.  Some shrubs like the Grace Smokebush will not die, but will die back to the ground every year, so they will never grow as large as we might see them in BC.

If you would like the challenge of pushing the Zone limits, don’t start with very expensive plants.  Buy smaller sized or less expensive varieties, and if you find Zone 4’s or 5’s work for you, then try more expensive plants.  Whether in-Zone or out-of-Zone, always water plants well in fall, and make sure there is enough snow cover or mulch.  What often kills our perennials isn’t the coldest days (or weeks) of winter, it is the spells of warm weather which we often get in February and March before Old Man Winter returns with a vengeance—these warm spells may fool the plants into breaking dormancy too soon, only to succumb to the cold later on.

Use the Zones as a guide only:  gardening is about experimenting and caring and bragging about your successes.  In our Greenhouse and Nursery, we stay on the conservative side, selling only Zone 2/3 and a few Zone 4 plants that have shown promising results in this area.

Soil Improvement

 Rare is the garden with perfect soil, so, to get maximum yield in our short seasons, we need to look at improving the soil we have.  This requires a bit of effort, but the payoff is well worth it.  Soil improvement should go on all the time.

Since there is so much raw material available during the growing season, I will start with composting, a relatively easy and inexpensive way to improve the soil.

What is Compost?  It’s implied in the name—partially decomposed organic matter, mostly plants and the manures of plant-eating animals.  Because its origin is plants, it contains the nutrients that our garden plants need to grow, in roughly the proportions needed.  Basically, it is recycling plant materials.

What does compost do?

1. Provides nutrition.
2. Improves soil structure by separating soil particles, thus improving tilth and providing for better aeration.
3. Increases the ability of the soil to retain moisture.
4. Contributes to the health of plants.
5. Moderates soil PH.  (acidity vs. alkalinity).
6. Encourages soil microorganisms and other beneficial soil inhabitants (e.g. earthworms).
   

How do you make good compost?

There are 2 ways to make compost: 

Hot composting can be a little trickier because it requires:

 a.) That dry matter (straw, leaves) and green matter (vegetable scraps, grass clippings, garden waste) be in the right (about 6 parts dry to 1 part green) proportions, and be chopped small.

b.) The right amount of moisture, and

c.) Frequent turning to introduce air into the pile for aerobic bacteria.  If all these factors are in place, the compost heats up quickly, the temperature kills seeds and disease organisms, and the compost is ready in several weeks.

Cold composting is easier, since all the materials are piled up, and left until they almost look like soil.  This can take several years since new materials are added over a long period of time.  It is unwise to add weeds to this kind of pile, as the seeds do not die, and will be spread with the compost.  We have 4 cold compost piles.  We built adjoining pens about 4’x4’x4’ out of old lumber.  When one pile is full, we move to the next compartment, then the next.  By the time the 3^rd is full, we are ready to use the first pile.

 What can go into a compost pile?

Kitchen vegetable scraps,  leaves and stalks of garden plants, straw, hay, manure from plant-eating animals, sod, grass clippings (in thin layers, not treated with weed killers), peat moss, coffee grounds and tea leaves, weeds that have not gone to seed, egg shells, crushed, wood ashes, chopped leaves (pile them up and run the lawn mower over them).

Don’t add too much of one thing at a time—layer them so there is variety throughout the pile.

A sprinkling of bone meal or alfalfa pellets will help to speed up the process.  Thin layers of fresh or partially decomposed manure will serve the same purpose.  Remember that most animal manures will contain viable weed seeds, except for sheep manure—sheep fully digest weed seeds.

What can’t go into a compost pile?

Roots of the cabbage family (root maggots), meat scraps or fat, cat/dog manure, inorganic material (metal or plastic), bones, branches or large pieces of wood, dairy products, diseased plants.

Does a compost pile smell? Attract flies?

Our piles smell very little as the materials decompose. We don’t notice many flies around our piles.  If the pile smells putrid, like a stagnant slough, that is because anaerobic bacteria have colonized it, usually because of too much moisture and compaction of wet materials, eliminating oxygen.  You can fork it over to let air in, and prevent this by adding layers of dry plant materials such as straw between green layers.

If I lived in town, and I wanted an open compost pile, I would do the Hot Composting method.  Better yet, purchase a closed compost bin and use it according to directions—this compost is ready quickly.

How do you use compost when it is ready?

You just spread it on.  Depending on how much you have, you can add 1” or 2” thickness around plants as mulch, you can spread it on the garden in fall or spring and till it in.  Or, you can make Compost tea:  Put about 1 ½ gallons of finished compost into a sack and tie the open end closed.  Almost fill a 5-gal (20L) pail of water.  Immerse the sack of compost.  Cover the bucket and let it steep for 3-7 days.  Pour the solution into a watering can or strain it and spray it on the plants.  Spread the contents of the bag into the garden.  You can make Manure tea the same way, but the manure has to be really well-rotted.

I’m sure glad that I planted some pots of mosquito plants this year.  Remember, mosquito plants don’t keep mosquitoes away just by sitting there.  Rub the leaves between your hands, and rub your hands all over your clothes and exposed skin.