Protecting Trees from Winter Damage

If you have ever planted and nurtured a tree along for two or three years and then had it suddenly die in the spring, or not leaf out at all after winter, you know how heartbreaking it can be. You not only lost the tree, but the time and effort it took to plant and nurture it. Here are a few tips to help ensure that your trees will endure our Idaho winters and burst into life again in the spring.

Feeding. Most trees do a large amount of their root growth during September, October, and November. Making sure they have sufficient nutrients available in the fall will go a long way towards insuring their long term health and growth. Also, because trees live for many years they are more likely to suffer from deficiencies of minor plant foods like iron. We formulated Town & Country Tree & Shrub Food with high iron and sulfur content to counteract our alkaline soils in east Idaho. And it’s slow release nitrogen will continue to feed for several months.

Feed your trees only in the spring and/or fall. Summer feedings can sometimes promote early fall growth that is more susceptible to frost damage. Mid September through October is the ideal time to feed most trees. Simply spread the granules throughout the root zone of the tree including beyond the drip line a few feet. Then water it in well to carry the plant food down to the roots.

Even better, feed your trees with Dr. Jimz Save-a-Tree. This amazing organic based fertilizer is the best plant food I’ve ever found. It is a liquid and is applied by hand, so it’s a little more time consuming, but there is nothing better. I would especially recommend it for extra special trees or those that are struggling. Because Save-a-Tree is organic and will not force feed the tree. It can be applied anytime of the year. But early fall is the best time of all.

Watering. Even if you don’t feed your trees it is extremely important that you give them a deep watering before winter. You need to apply enough water to soak down about 2 feet. In most soils that means applying about 2 inches of water. You can apply the water by simply placing a hose sprinkler under the tree. Place a tuna fish can in the area also and move the sprinkler when it has filled the can to 2 inches deep. You can also use a soaker hose or even just let an open ended hose run for a period of time. But it is a little more difficult to measure the amount of water that way.

Wrapping a young tree in my yard.

Wrapping trunks. If you have young trees or any trees that have very thin bark you might want to consider wrapping the trunks with a white breathable tree wrap to protect them from sun scald damage during the winter. I recommend wrapping them in October and taking the wrap off in April. The purpose for the wrap is to reflect the sunlight off of the trunk in the winter to keep the trunk from heating up on sunny days when the nighttime temperature is well below freezing, or even below zero. It is the constant freezing and thawing of the bark that can cause the bark to crack and even die

Fall wrapped evergreens. Photo: Univ. of Minnesota

Wrap evergreens. If you have planted some new young evergreens this year you might consider wrapping them with burlap to protect them from windburn this winter. Older trees are usually fine because their roots have penetrated deep below the frost line, but younger trees have shallow roots. Once the ground freezes they have no way to replace the water lost from the needles due to winter sun and wind. Wrapping with burlap will protect them from both sun and wind while still allowing air circulation. Never wrap with plastic as it can heat up inside and kill the trees. Arborvitae and Alberta Spruce are the most susceptible to winter burn. Wrapping evergreens with burlap can also protect the plants from damage by a heavy snow pack, or from hungry deer. Colorado spruce and mugho pine generally need no wrapping.


Fall Needle Drop

Austrian Pine shedding needles in the fall.

We get a lot of calls at the nursery this time of year from people concerned about their evergreens that have suddenly developed brown or yellow needles on the interior of the tree that are now beginning to drop. It is particularly noticeable on long needled Austrian pine and on columnar arborvitae. Let me set your mind at ease. This is a natural occurrence that happens every fall, although some years it will be more pronounced than others.

Fall needle drop on arborvitae. Photo: Purdue University

Although called “evergreens” these plants don’t hold their leaves (or needles) forever. They drop in the fall just like maples. But unlike maples that drop all of their leaves every year, evergreens hold their needles for 2 to 5 years before they drop. So, if it only happens in the fall, and only affects needles further down the branch (not this year’s growth) then you can rest assured that your tree is just doing what nature intended.

Preparing for the First Fall Frost

East Idaho’s growing season is notoriously short most years, and home gardeners usually have an abundance of produce that is not yet ready to harvest when that first prediction of frost comes in the fall. So the first frost of the fall season , or even the forecast of such, is a cause of great anxiety for the home gardener. But the first killing frost doesn’t necessarily mean the end of your garden harvest. Taking a few minutes to protect tender crops can often extend the harvest well into October.

Light Frost (29-32)
Usually the first frost of fall is a light one and you can cover your tender plants with things as light as a bed sheet or plastic sheeting to protect them, even plastic garbage bags may work. The trick is to anchor the covering so wind gusts don’t remove your protection. The idea when covering your plants is to trap heat from the soil in the air immediately around the plants. It’s important to uncover them when temperatures warm up, especially if you used plastic for protection. Plastic will trap the sun’s heat the next day and plants may scorch. Watering your crops before the frost is also helpful. Well hydrated plants are less susceptible to frost damage.

If you are unable to cover your plants try turning on the sprinkler just before the temperature drops below freezing and keep it running until the ice has melted the next day. The heat given off as the ice forms can actually keep the plant from freezing.

Hard Frost (28 degrees or lower)
When temperatures drop below 28 degrees simply watering with a sprinkler or covering with bed sheets will not be sufficient. You will need to cover with blankets or something with some real insulation value for sufficient protection. If possible, remove the blankets during the day to allow the sun (if there is any) to warm up the soil and provide light for the plants to stay healthy. If it freezes several nights in a row you will need to cover them each night.

Squash plants damaged by frost.

Tender Plants
The most frost sensitive veggies include cucurbits (cucumbers, squash, pumpkin, melons), beans, eggplant, peppers, and tomatoes. Sweet corn is also quite tender, but difficult to cover.

Tender flowers include impatiens, marigolds, geraniums, begonias, coleus, dahlia, and zinnia.

Frost Tolerant Plants
Frost tolerant crops include cole crops (cabbage, broccoli, cauliflower, brussel sprouts, kohlrabi), root crops (radish, beet, carrot, parsnips, turnips), leaf crops (lettuce, spinach, chard), chives, Jerusalem artichokes, and peas.  Onions are frost tolerant but may be damaged if the bulb has pushed above ground, which they often do. Potato vines will freeze easily but the tubers are generally okay until the ground freezes down a couple of inches. Brussels sprouts are actually better after a light frost. Root crops can overwinter in the garden.

Hardy flowers include petunia, snapdragon, pansy, alyssum, dusty miller. Click here for a list of flowers and their cold hardiness.

Harvesting and Storage
When frost threatens, your first step is to harvest all ripe fruit before the frost.

Winter squash and pumpkins intended for storage should be harvested before a hard frost because temperatures in the low 20’s or frost for an extended period will shorten their storage life. If they are subjected to a severe freeze, harvest them immediately and cook, freeze or can them as soon as possible.

Tomatoes that get lightly frosted can be canned or frozen right away, but they will deteriorate rapidly if you try to hold them. Green tomatoes picked before frost can be stored at 50 to 55 degrees F and ripened for several weeks. Those picked after frost will not ripen or keep long, however.

Pepper plants blacken at the first frost. If you can’t cover them, pick the peppers before frost.

Though bean plants are killed by frost or a hard freeze, the pods do not show immediate damage. Pick and use or process them as soon as possible, however, for best results.

Summer squash plants don’t tolerate freezing at all. Pick summer squash before frost.

Sweet corn can usually be harvested and eaten, canned, or frozen after a light frost, but a hard frost may ruin it.

The cole crops (broccoli, cabbage, Chinese cabbage, cauliflower and Brussels sprouts), will tolerate fairly heavy frost; though a really hard freeze will reduce the keeping quality of even these hardy veggies. But unless they are predicting temperatures in the low 20’s, it’s not necessary to rush out and cover or harvest them.

When to Pick Apples

With the prediction of a season ending frost coming Wednesday night I will try to head off a question that I’m sure will come up about fruit crops.

Question: Should I pick my fruit before the frost?
Answer: It depends. If the fruit is ripe, by all means pick it. Contrary to a freely circulated old wives tale, fruit such as apples and grapes do not need a frost to “set” the sugars. If they are ripe they should be harvested before the frost. Here is an excerpt from the Utah Master Gardener manual:

Many hobby orchardists have the mistaken notion that winter apples aren’t properly ripe until they have been frozen. The conditions that result in ripening are cold nights (not freezing) and sunny days. Ripe apples will freeze when the fruit temperature is about 28 F. Once frozen and then thawed, apple tissue will begin to break down rapidly. If fruit freezes on the tree before it can be picked, it may not be a total loss. Wait until the fruit thaws on the tree, then pick and eat or process (juice or sauce) as quickly as possible.

If peaches and plums freeze hard, they will break down quickly after they thaw.  Apples tend to tolerate freezing somewhat better. A light frost will not hurt apples, but if it gets into the low 20’s they will be alright to eat after they thaw, but the storage life will be drastically reduced. At about 22°F, fruit cell death and damage occurs causing browning and breakdown soon after thawing. If apples are frozen on the surface, do not pick until they are fully thawed to prevent bruising. If browning and breakdown do not show up soon after thawing, the apples have survived freezing, but any freezing causes softening and faster deterioration during storage.  Apples that were frozen will not store as long as unfrozen apples.

Picking fruit at optimum maturity is the goal.  Go by taste and color to determine the best time to pick.  For maintaining quality after harvest, apples should be cooled quickly.  Ideally they should be cooled within 24-36 hours after picking.  Storage temperatures should be 32°-38°F for most varieties.  Most late season apples can be stored from 2-4 months at these low temperatures.Homeowners typically do not have access to controlled temperature storage, so just store them as cool as possible without allowing them to freeze.

Having said all that, based on the temperatures that are being predicted in east Idaho for Wednesday night I would pick all my fruit unless they are not ripe, in which case I would just leave them on the tree and hope the weather prediction is wrong.



Fall is for Decorating

Fall is a wonderful time of year in east Idaho! The weather is typically sunny and warm and the nights are cool and refreshing. With the changing of the seasons I like to change out the pots and planters in front of our home for the fall season. When we don’t get an early frost I sometimes hesitate to rip out flowers that are looking a little worse for wear yet are still blooming, but I know the frost is not too far away and I want to change the decor to match the season. So today I pulled the flowers out of my planters and replaced them with a fall theme using fall flowers including pansies, asters, and kale, and cornstalks, pumpkins, and gourds. And yes, I removed the soil from the planter and replaced it with a white pumpkin that the little girl is carrying in her basket. I love the change. It expresses the tone of the season very well, and will still look great when we start having frosts at night, which could happen beginning Wednesday night according to the weather forecast. I took a few pictures of how it looks today.

Harvesting Grapes

It’s October! Can you believe it? I’ve really been enjoying the nice fall weather, but I’m so not ready for winter yet. I’d really like to enjoy a few more weeks of this gorgeous Idaho autumn weather, but the forecast is calling for frost Wednesday night throughout the Snake River plain and continuing for several nights in a row. They are currently only predicting light frost in the valley, but higher elevations could see lows into the teens. So I think it’s time to harvest the last of the crops. The only thing I think I will still cover and try to keep going is my one hill of cantaloupe. I have half a dozen fruit that are almost ready, but not quite, and I really want to be able to enjoy some fresh melons out of my garden, so I hope I can keep them going for another week or two.

I’ve already removed the cornstalks from my garden and decorated with them at the entry to the house. I’ll do my last picking of tomatoes tonight and let nature take its course on what remains. We’ve had a good crop already so I won’t feel too bad if the frost gets them. Right now we are busy with the last item to be harvested in the garden- grapes. We have a pretty good crop this year of both Himrod Seedless and Swenson Red Seedless. If you came to the “Sweet Corn Free for All” at Town & Country Gardens last Saturday in Idaho Falls you had a chance to sample some of my harvest.

Grapes are actually not too difficult to grow in zone 4 if you choose your varieties carefully. We have had pretty good success over the years with seedless varieties such as Himrod, Interlaken, Canadice, and Swenson Red. We’ve also had pretty good luck with Concord, Bluebell, and Reliance. Beta and Valiant are zone 3 hardy Concord types that can even be grown successfully in colder areas like Rexburg and Driggs.

When it comes to pruning do as I say, not as I do.  I haven’t pruned my grapes in a couple of years and they have grown a bit out of control. I am going to have to head into the jungle with a machete to get them back in some semblance of order.

What I meant to do, but haven’t taken the time to keep up with it is prune them like this diagram suggests.

Most backyard grapes are best trained using the four arm system. This is done by stretching two stout wires between two posts that have been spaced ten feet apart. The top wire is tightly strung about five feet off the ground, and the second about two feet. The grape vine is planted between the two posts. Over time a strong central trunk is trained with only four arms, or branches, growing out of it. When planting a new vine, prune it back so that only two buds are left above ground. This may seem a little drastic, but it is necessary to develop a strong central trunk and a healthy grape plant. When new canes have grown out from the buds and are about two feet long, choose the strongest one and fasten it loosely to the end of a string. Tie this to the top wire. This will lead the cane straight up so that it will become the trunk and lateral canes will grow from it to form the four arms.

Or… just let it grow into a jungle like I have. A bit messy, and probably won’t produce as heavily, but you’ll still get a pretty good crop.

Mexican Roasted Corn

Today I enjoyed some of the most delicious corn-on-the-cob I’ve ever eaten. We hired Grove City Gardens of Blackfoot, Idaho to come by the Idaho Falls store and cook up some Mexican Roasted Corn for our customers today. It was not like anything I’d ever eaten before and was a big hit with everyone.

When I was told what they put on the corn I have to be honest, it sounded less than appetizing. The dried Mexican cheese, lime, and chili powder all sounded great, but when they said they slather the corn with mayonnaise they lost me. However, now that I’ve tried it, I’m sold.

Grove City Gardens has special roasters that they use to roast the corn before skewering the cob on a stick and adding the toppings. But you can cook it at home by either baking it in the oven or grilling it on the barbecue grill. I found this recipe on the Food Blogga blog on the internet. It sounds very similar to what we enjoyed today at the garden center.

Elote, or Mexican Grilled Corn
Serves 4

4 ears sweet corn
1/4 cup mayonnaise
1/2 teaspoon lime juice
1/8 teaspoon cayenne pepper of chile powder
salt, to taste
2/3 cup crumbled cotija anejo cheese
lime wedges
extra cayenne pepper or chile powder, for sprinkling
fresh finely chopped cilantro for optional garnish

Soak corn (in husks) in cold water for 25-30 minutes.

Prepare a medium-hot grill. Peel back the corn husks leaving them attached at the end. Remove the silk. Pull the husks back up and tie with a spare piece of husk or a small piece of cooking twine. Place the ears on the grill. Cook 20-25 minutes, turning several times to ensure even roasting. The kernels should be soft when fully cooked.

If you’d like the kernels more charred, then simply follow the above instructions, but cook in husks for 15 minutes only. Then cool ears slightly, pull back the husks (to use as handles) and place the ears directly on the grill (with husks overhanging the side) for 5-7 minutes, or until they reach desired level of charring.

Place crumbled cheese on a plate large enough to fit an ear of corn. In a small bowl mix the mayonnaise, lime juice, cayenne pepper or chile powder, and salt. When the corn is cooked, brush each ear with some mayo sauce then roll in the cheese. Serve with lime wedges, additional cayenne pepper or chile powder, and fresh finely chopped cilantro.

** Cotija anejo, a mild-flavored Mexican cheese with a crumbly texture, can be found in Mexican markets or in the refrigerator section of most major supermarkets. Queso fresco, another mild Mexican cheese, is a good substitute and also can be found in most major supermarkets.

Note: If you are unable to grill outdoors, then you can oven roast the corn. Preheat oven to 350 degrees F and place corn in husks (no need to soak first) directly on the middle rack of the oven for 30 minutes, or until corn is soft to the touch. Allow to cool slightly, then remove husks and silks, and add toppings.


Fall Colors near Swan Valley, Idaho

Yesterday I took a drive up through Swan Valley to Palisades reservoir. I took the Falls Creek road along the south side of the river to the dam where I crossed back over on the new bridge below the dam. The fall colors are absolutely spectacular right now. If you live nearby and have the chance, be sure to take a ride up there this week. The colors are already peaking, so don’t delay. Most of these pictures were taken on the road up towards the Red Ridge trail head.