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What is your Hardiness Zone? What does it mean, and how does it affect your garden choices?

The US Department of Agriculture drew up the Hardiness Zone map as a standard for farmers and gardeners to better understand their growing conditions. It is based on average winter minimum temperature and broken down into 10F degree segments. Fairly recently, this was further parsed into 5F differences using the letters “a” and “b”. Here in Lancaster County we are Zone 6b, meaning our average coldest night is -5F.

When you look at a plant tag or catalogue it often gives the Hardiness Zone as a range. For example, Black-eyed Susans are hardy from Zone 3-9. This means they can live in an area with winter temperatures as low as -35F to areas with lows down to 25F. Geographically this corresponds to the range from Minnesota to Georgia.

There are some drawbacks to this system. It does not take into account summer heat and humidity. Some plants that can handle the winters, may melt out in the summers. It also does not regard snow cover. With a layer of insulating snow- plants can tolerate much lower winter temperatures than without that protection.

To address the first problem, a corresponding Heat Zone system was devised by the American Horticulture Society. It is based on the average number of days above 86F. Why 86F? This is the temperature when most plants stop actively growing and suffer from heat “distress”. Prolonged exposure to temperatures above 86F can cause problems setting fruit, bud drop, leaf yellowing etc. Zone 1 corresponds to 1 day above 86F. Alaska and parts of the Rocky Mountains are in Zone 1. Zone 12 includes area with more than 210 days above 86F. South Florida, South Texas, and the Arizona desert are about the only spots of Zone 12 in the US. Lancaster County is on the border of Heat Zone 5-6. Meaning we have between 30-60 days above 86F. Otherwise known as July. This system gives a more complete answer for understanding if a plant will do well in your garden, but is not yet widely used.

Microclimate also is an issue. If you live downtown, the heat sink of the buildings and paved roads affords several degrees. Likewise, right up against your house is more protected and a bit warmer than in an exposed area of your yard. My neighbor has a stunning camellia bush that I so envy. Most camellias are zone 7 or even 8. If you remember above, Kirkwood is zone 6b. Ann’s camellia is surrounded on three sides by evergreens to block the wind and faces south. It is beautiful every year and I try to drive past as often as possible when it is in bloom.

Cold hardiness and bud hardiness are also two different stories. This refers more to trees and shrubs than perennials. A plant may be cold hardy in its root system, but buds set the previous summer may suffer from low temperatures. For those of you whose hydrangeas don’t bloom- this is why.

The gardening season is almost upon us. As you chose plants this year, think about the cold Hardiness Zone and Heat Zone maps and how they can help you make more informed choices.

March certainly came in like a lion!

Last week’s sustained winds and forceful gusting did a whammy on most of Eastern PA and Northern Maryland. Thousands of homes and business were without power, downed trees blocked the roads, and enough shingles dislodged to keep roofers happy for the next few weeks.

Here at the farm we had lots of blowing debris but only minor damage. We did lose a greenhouse plastic covering, but were very fortunate that it was an unheated house. Neighbors had toasty greenhouses growing tiny annuals exposed which caused a mad rush to find any warm nook and cranny to shove plants into until the structure could be recovered.

What do these cold temps and high winds mean for your gardens? Thankfully, not much. Most of your perennials and even deciduous trees and shrubs are still slumbering peacefully with their food storage below ground not subject to March’s bitter gales. Even most tree and shrub buds have not swollen or broken yet, so will probably be fine.

The plants that are most susceptible to March’s temper are broad leaf evergreens and conifers. Plants like rhododendrons and azaleas and their friends are broad leaf evergreens. They continue to transpire (exchange gasses and water vapor) through tiny pores in their leaves through the winter. When the ground is frozen, the water droplets in the soil are too. This makes it difficult for plants to draw up water through their roots. Unless they have deep roots below the frost line, transpiring too much over the winter can be a problem for evergreens. Strong, sustained winds can sound a death knell for some.

To protect vulnerable young evergreens, some gardeners wrap burlap or other material around the plant to buffet the winds. You don’t want to use plastic, as this will retain too much heat and moisture. Also, be careful about trapping too many dead leaves and providing homes for small rodents that like nothing better than to gnaw the crowns and tender branches of your shrubs.

Another option is spraying the leaves with an anti-dessicant. These treatments provide an extra waxy layer to the surface of the leaf to help prevent moisture loss. In this area, these are best applied once anytime between Jan-March. Treatment too early in the fall can be counterproductive. Larger trees with well-established root systems are generally better able to maintain a moisture balance between the roots and leaves and do not require special treatment.

Don’t worry about daffodils, tulips or perennials starting to peek above the soil. They will generally halt their progress until the weather warms.

Looking around the area, despite the snow- farmers are getting ready for spring. I’ve seen several farms with plastic sheeting laid out on the ground over rows, or in large rectangles. This is for solarization. The sunlight through the clear plastic warms the soil and kills weeds underneath. Covering a bed with plastic sheeting kills weeds quickly in the summer. However, this time of year the main purpose is to warm the soil to gentle the transplant shock of young vegetable seedlings. Planting into plastic row covers can give a several week head start to produce growers.

Another common sight in Lancaster County this time of year is the steam sterilizer. It is an old-time steam-driven farm implement that forces steam into the first few inches of field soil. This kills harmful bacteria and fungal disease spores and weed seeds that would damage a crop. If you think you are hearing a train whistle, it is probably the field sterilizer.

For those of you getting sick of winter, take heart, the signs of spring are starting to appear.

Image: Bog Rosemary in the snow after we lost the greenhouse covering.  KGB

For the last few years succulents have been hot, hot, HOT! Meaning that in almost every gardening magazine as well as home decorating websites, and Pintrest have featured these easy-to-grow plants. They certainly are a gateway to getting young people and the often-maligned generation, the Milennials, interested in gardening. We’ve even grown them to give as wedding and baby shower favors. They are definitely mainstream now.

And rightfully so. Tender succulents like kalanchoe, jade plants and aloe grow well indoors in a sunny dish garden with little attention. Hardy succulents come in a variety of shapes and colors and grow just as easily unattended outside in a sunny flower bed.

The key is good drainage. When growing indoors, use a pot with drainage holes. Water enough to wet the soil completely, then allow the plant to dry out. A thorough watering once a week is about right. Some people like to grow succulents in a glass terrarium. This can be a bit tricky to not keep too wet. Only water enough to dampen the soil, then let it dry out until the next watering. Spritzing them with a water bottle won’t effectively get the water to the roots and I don’t recommend it.

We have a succulent-filled green roof doghouse (pictured above) at the farm that we planted six years ago. It has built-in drainage holes at the bottom. It seems to do best when it rains about once a week. It’s only been watered a handful of times over the last few years during several weeks of hot, dry weather.

Succulents look their best when mixed. They come in such interesting shapes and sizes, it’s not hard to make a combination planter. Our doghouse is a mixture of red, yellow and green foliaged sedums, ice plants that bloom in pink, and red and green webbed hens-and-chicks. Most of them are evergreen and retain color all winter. They also bloom at various times over the spring and summer; there is always something interesting to see.

The taller, upright sedums usually bloom in the fall. Some of my favorites are the dark foliaged ‘Matrona’ with deep reddish-pink blossoms and the variegated leaf of ‘Autumn Charm’ with light pink flowers. These make such great combinations with fall mums and ornamental grasses.

If you kept tender succulents outdoors over the summer and are planning to bring them in for the winter, inspect them well for bugs. Aphids seem to like the fleshy leaves. Wash them off, or spray with horticultural oil to rid them of pests before bringing them in the house. A sunny east-facing window is best. If they are not getting enough light, you will notice they start to stretch.

Succulents are popular for a reason. They are colorful and easy to grow, and who doesn’t like that?

This last week I have been on a mission. Summer was full of activities with the kids, and I let part of my garden get a but…ahem…wild. A week ago as I was walking through the beautiful blooming helenium and cardinal flowers, I was aghast to see a ragweed that towered over my head. Where did that come from?! (Pictured left)

This summer’s cooler temperatures and plentiful rainfall encouraged weeds to grow like crazy and now is the time to get them under control before they set seeds and multiply your problems next year.

Break it down by sections and set goals. If you are like me you see a large area that needs tackling and it is overwhelming. Don’t beat yourself up doing it all at once. I encourage you to do a bit every day or set a time goal. Work on it for a hour after work or when the kids get home from school and let them run some energy off. Better yet, get them to help!

Once I had some of the weeds pulled, I found places where I had some room to add more fall-blooming plants. Ground covered by desired plants can’t grow weeds.

Ornamental grass is beautiful this time of year. ‘Northwind’ Panicum is one of my favorite taller grasses and ‘Hameln’ pennisetum is a great lower-growing grass for the front of the border. The little bluestem ‘Standing Ovation’ has really impressed me the last few years with its blue-red color and upright habit. Asters are just starting to bloom now as are sedums, perennial mums and anemones. Coral bells, plumbago, toad lilies and carex will add some color to your shady spots.

If you are wanting to add some shrubs, the autumn-berrying shrubs like purple beauty berry, viburnums, and winterberry holly are all starting to show some color. Shrubs with attractive fall leaf color include fothergilla (bottle brush), itea, and oakleaf hydrangea.

Fall is a preferred time to plant perennials and shrubs as the soil is still warm and roots establish quickly before the plant goes into winter dormany. You will also start to see those familiar bulb boxes in stores. September is prime time for planting daffodils, tulips, crocus and allium for spring.

People always ask if you should do garden cleanup in the fall or wait until spring. Leaving seed head on your perennials will feed the birds, but it will also spread a bunch of seeds around your garden. Goldfinches have been happily feeding on my coneflowers the last few days, but I am also forever pulling volunteers. Find a happy medium and cut things back that you don’t want everywhere, but leave some plants standing to feed wildlife and for habitat for beneficial insects to overwinter.

We still have a good two months left in the gardening season. A little effort now will pay big dividends in the spring

This summer the kids wanted to plant lots of butterfly-attracting plants in the beds around the house. The key to butterflies is to have both foods for the caterpillars to eat (larval foods) and nectar-bearing foods for the adults. We already had a ton of coreopsis, coneflowers, zinnias and petunias for the adults, we needed to work on larval foods. We do have Tulip poplars for the Eastern Tiger Swallotails and violets for the frittilaries but they decided to try to help the rock stars of the butterfly world, Monarchs.

Monarchs eat strictly milkweed as caterpillars, but there are several kinds. The kids helped me put in about 2 dozen tropical milkweed plants (Asclepias currasavica) and by mid-July their work paid off. I especially like tropical milkweed because it produces a ton of leaves for the monarch caterpillars to eat. The perennial swamp milkweed, butterfly weed and common milkweed are also good options.

When we spied the first Monarch sipping nectar from the flowers, we hoped she would lay her eggs. A few days later we found itty-bitty baby caterpillars happily munching on the leaves. Success!

Our second close encounter with butterflies was on our staff to Hershey Gardens. In addition to the rose garden, for which they are famous, they now have a butterfly sanctuary. The recently-constructed atrium houses 500-600 butterflies from around the world. Brooke, the chief horticulturist for the Butterfly Atrium, works closely with the USDA to import tropical species in the chrysalis stage. They emerge in a special cabinet, then are released into the atrium where the spend their adulthood.

The staff are very deliberate in their plant selection, growing plants high in nectar like plumeria, pentas and shrimp plant to feed the adult butterflies. They also have feeding stations with Gatorade and ripe fruit.

The conservatory contains no larval food plants as the staff are not permitted to hatch eggs and rear caterpillars. A double air-lock system ensures the butterflies do not escape.

After our trip to Hershey, the kids decided we should bring the caterpillars inside so our chickens wouldn’t eat them. Of the 5 caterpillars we first brought in, four made chrysalises. After 7-9 days the jewel-green chrysalises became clear and the black-and-gold butterflies were ready to emerge. Their cocoons cracked open and after a few hours to allow their wings to dry and firm up, we released them back outside.

Now every few days we scout the plants for caterpillars and eggs, pick leaves, and set up more Monarch nurseries on my kitchen counter. The caterpillars molt several times before they are ready to pupate and need lots of leaves to munch on. The first few days I just picked individual leaves and put them on the bottom of a Mason jar. Every morning, we scoop out the frass (fancy word for poop) and pick more leaves. I quickly found it is easier to pick stems 6-8” long and wrap the bottom in moist paper towel. That makes clean-up faster.

We lost a few. One small caterpillar pulled a Houdini and ended up on the floor to be stepped on by the dog. One chrysalis became dislodged from the top of the container and the butterfly never emerged. But by and large we have been successful. The kids researched butterflies and the best way to rear them indoors on the internet; it was a great learning experience for Liam and Ali.

When we set them free they sipped some nectar from the ‘Black and Blue’ Salvia, and other flowers in the yard. Then they winged their way to freedom. Its been a good summer.