Use warm temperatures during January thaw to control insects with water

 

During many winters we have a January thaw. We had a very welcomed warm spell last week and it looks like there will be another warm-up this week too, even though it may not be quite as warm this time around.

I always like to take advantage of those warm mid-winter days to freshen up my house plants and others that I have growing  inside.

Three of my citrus trees, which are about six feet tall including the pot, share space in a southern window in my woodworking area. That means their leaves are often covered in fine sawdust depending on the project I’m working on. I recently finished a project that required quite a bit of sanding which developed a lot of sawdust that settled on the citrus tree leaves.

Last week’s thaw gave me the opportunity to haul out my two wheel hand-truck and wheel out the heavy potted trees out to the driveway. I didn’t need to hose off the plants because of the drenching rain that came later in the day. That rain was all that was needed to get them clean. Since then however, I’ve generated more saw dust and they’re all dusty again.

The good news is that temperatures are predicted to be near 50 degrees F during the next couple of days. That’ll be the the perfect time to wheel them back out and rinse them off again, only this time I’ll have to drag out the hose. Some of my larger house plants are going to get a good outdoor rinsing too.

I rinse my citrus trees every year we have a January thaw. My trees are 17 years old.

This mid-winter rinsing not only washes off dust but even more importantly, it removes many of the small insect and other pests found on indoor plants such as spider mites, mealy bugs and scale. The population of  those types of pests can build up to a damaging level inside a warm, dry winter environment like we have in many Michigan homes this time of year. Rinsing with water knocks back the insect population to a tolerable level.

Mature citrus tree leaves are tough and can handle strong streams of water. Other plants though have more tender leaves which can be bruised by a too vigorous spray from an exuberant gardener — I know, I’ve done it.

If you plan to do a mid-winter rinsing, I suggest you start with a fine spray and increase the pressure if needed.  You’ll have to use your best judgement as you go along. I use a three-hole nozzle that puts out a very fine, yet strong stream of water that knocks off just about everything without damaging leaves. Be sure to spray the under-side of the leaves. That’s where the biggest concentration of pests will be hiding.

Bob

 

 

 

 

 

 

 

Use old camera as light meter for plants

If you are like me, you find it hard to toss or give away any of your really good stuff, even if it is obsolete. I still have my old SLR film camera, a Pentax K1000 that I bought way back when. It was one of the first things that I splurged on during my early adult life when I really couldn’t afford it. That is probably why I feel so attached to it even though I haven’t taken any photos with it for many years.

There is however another alternate use for that old camera of yours still bumping around in your closet. It can be used as a light meter to determine the amount of light available in the spots where you are planning to keep your plants indoors during the winter.

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This method measures the reflected light from an area as opposed to some light meters that you point at the light source. Set the shutter speed to 1/60 and the ASA to 25. Take a sheet of white paper and place it in the spot you want to measure. Point your camera at the paper and look through the viewfinder. Move so that the white of the paper is the only thing you can see in the viewfinder. Follow the meter inside the view finder and adjust the f/stop until the the meter is in the optimum range for taking a photo. From there you can use the f/stop to get a fairly good approximation of foot candles (fc): f/2 equals 40 fc; f/2.8 =75; f/4=150 fc; f/5.6=300 fc; f/8=600; f/11=1200 fc; f/16=2400 fc. Each f/stop move indicates a doubling of  foot candles from the previous setting. If you own an older camera like this you probably remember what ASA and f/stop means, everyone else will have to look it up.

Foot candles reading below 75 is considered low light. Readings up to 200 fc is moderate light while anything over 300 fc is bright light. That will give you some idea where to place which plants over the winter.

Now, if only I can figure out how to blog using my manual typewriter.

Bob

 

 

 

Mother’s day plant sale at Matthaei Botanical Gardens this weekend

The Matthaei Botanical Gardens – Nichols Arboretum annual Mother’s Day Plant Sale is coming up this weekend, May 13 and 14.

About three weeks ago I visited the Gardens and got a sneak peek at the plants growing in the greenhouse. I can tell you that these are no ordinary, anonymous plants grown by an impersonal factory growing operation. They are lovingly grown and tended by Adrienne O’Brien and her helpers right in the greenhouse at the Botanical Gardens. When I was there, the plants were still young but were growing strong and looked absolutely wonderful.

Horticulturist Adrienne _________ leads team of plant grower at Matthaei Botanical Gardens - Nichols Arboretum
Horticulturist Adrienne O’ Brien leads her team of plant growers at Matthaei Botanical Gardens – Nichols Arboretum.

 

A month ago Adrienne was worried that the plants were ahead of schedule.
A month ago Adrienne was worried that the plants were ahead of schedule.

Now the plants are ready to go home to Mother’s house.

The plants will be sold in the same greenhouse that they were grown in.
The plants will be sold in the same greenhouse that they were grown in.
Wide variety of beautiful hanging baskets
Wide variety of beautiful hanging baskets
Container plants make a great gift for Mom on Mother's Day.
Container plants make a great gift for Mom on Mother’s Day.
Whimsical planters like these are lots of fun.
Whimsical planters like these are lots of fun.

 

The sale runs from 10:00 am to 4:30 pm both days (9:00 am if you are a member). Matthaei Botanical Gardens is located at 1800 N. Dixboro Road, south of Plymouth Road, Ann Arbor.

Bob

Make plant tags from broken window blinds

A new winter gardening project presented itself yesterday. The frame on one of our window blinds snapped as I was pulling on the cord to open it and the whole works crashed to the floor.

As it turns out, mini-blind slats make fine pot markers, you know, those small white tags that gardeners use to identify trays and pots of seedlings. The slats are just about the same width as the markers that are sold in gardening departments every spring.

One big advantage homemade markers have over the garden-store variety is that you can easily cut them with a pair of scissors to whatever length you need, short ones for flats of seedlings, or longer ones for potted plants.

Just this one set of window blinds will provide enough material for dozens of plant tags
Just this one set of window blinds will provide enough material for dozens of plant tags

Homemade tags decreases the chance that seedlings will be mislabeled. Since each set of blinds will yield dozens of markers, you won’t be tempted to skimp on labels, that way every pot or six-pack divider can have it’s own tag.

Re-purposing old blinds reduces the amount of plastic debris that eventually finds it way into the landfill. And you save a few bucks along the way. Plus, it’s fun making your own gardening supplies and this happens to be a very easy project.

I’m looking at that high-quality braided pull-cord on those blinds too, but I haven’t figured out a use for that yet.

Bob

Check those plants you moved indoors for scale insects

With Christmas and other hectic, holiday happenings over, now is a good time to check those plants you brought inside for winter.

When potted plants live outside during the summer, they become susceptible to infestations of all kinds of insects. Usually, if they are in reasonably good health they can tolerate a moderate insect attack. And natural predators like lady bugs and lace wings will keep the bad insect population to a minimum. But when plants are moved indoors, they loose the protection of those natural predators which can allow the insect population to grow.

Scale insects are the ones I have the most problem with. When I start to find a sticky coating, called “honeydew”, on the lower leaves, table, nearby furniture or floor, I know that the scale insects are ramping up their feeding. They can get out of hand quickly at that point and do some real damage to the plant– not to mention the mess they make. Honeydew is sometimes mistakenly called “sap” because the plant owner thinks it is the plant leaking sap all over the place. It’s not always easy to spot a scale infestation if you’ve never seen it before.

The brown ovals are the outer shells of the scale insects. The clear substance is honeydew.
The brown ovals are the outer shells of the scale insects. The clear substance is honeydew.

Scale feed by poking their “beak” into the the plant and feeding on the nutrients from the plant juices. Like most other animals, they excrete waste. In this case it is in the form of that sticky, syrupy  honeydew. Honeydew contains a high concentration of sugar. But how and why do scale insects produce so much sticky residue? The answer is that they pick their feeding spot very carefully. If you remember from middle school biology, plants have two basic types of tubes inside. Those that carry water from the roots up into the plant are called xylem. The other tubes that carry nutrients manufactured by the leaves to the rest of the plant are called phloem.

It is the phloem where the scale insects like to poke their beaks. If they pierced a xylem tube by mistake, all they would get is mostly water and some dissolved minerals. The phloem sap contains sugars for energy, proteins for growth and other things necessary to sustain plant and animal life.

The scale can’t use all of the sugar dissolved in the phloem juices so they excrete the excess sugar which then falls all over the immediate area. Since it is primarily sugar, it is water soluble and fairly easy to clean up with a damp cloth. Small plants can be rinsed off in the sink or bathtub.

My citrus trees are way too big to rinse off in the bathtub and too heavy for me to move to the shower. Instead I use a damp cloth — or even my bare fingers– to rub off the scale from the leaves and branches whenever I find them. I find that if I do a few leaves every day, I can usually keep up with the multiplying insect population, especially if I remember to start early. If you wait too long, it can turn into a tedious, frustrating job.

One other by-product of honeydew is sooty mold, a black, powdery mold that grows om the surface of leaves and other surfaces. All of that sugar provides food for sooty-mold fungus which will grow and leave sticky surfaces with an unsightly black film that can rub off onto clothing.

Even though you may feel overwhelmed by the holiday rush, remember your plants, they will thank you for it.

Bob

 

Protect potted perennials from winter cold

Just about every year, going into winter, I have perennials or other potted plants left over from the growing season that never got planted for one reason or another. I usually have plans for them so I like to keep them over winter.

It’s a good idea to keep plants out as long as possible in the fall. An occasional short cold snap doesn’t bother the plants at all. This year the mild fall weather lasted so long that I just now got most of them put away into their winter storage spots.

The most valuable plants I worry about are my bonsai.  They are several years old, my false sequoia is well over 20 years old. All the bonsai are hardy trees that require a cold dormant period to complete their annual life cycle so have to be kept outside during the winter.

There’s a spot under my mature pine trees where the bonsai spend the winter. There I dig a hole and place them in the hole on their sides. Placing them sideways keeps snow melt water (which we get sometimes) from accumulating in the pots. That reduces the chance that the terracotta pots will crack when the water re-freezes. Soil excavated from the hole gets banked up over the pots and the crown of the trees. I then rake plenty pine needles over the tops to insulate them from the cold winter temperature and wind. The entire storage area gets covered with a tarp or other kind of covering.

 

I put the rest of my perennials in various places around my property. I have a number of  left over grape cuttings that I rooted this spring. Those I tucked away in a well-drained spot in the vegetable garden. A few miscellaneous perennial flowers are mixed in there with the grapes.

Pots in trench

A few years back I had some potted elderberry plants that I overwintered in the ground. I buried the pots as usual but put them in a new place, somewhere way out of the way. When spring arrived I was so busy that I forgot I even had elderberry plants. It wasn’t until late June that I saw a group of elderberries growing out of the soil that I remembered I stored them there the previous fall. I learned how a squirrel feels when it forgets where it buried its acorns.

The soil is still unfrozen thanks to our recent mild temperatures but that probably won’t last long so those plants into the ground now while you can.

Bob

Why does a jade plant bloom?

One of our jade plants has started blooming this week. Anyone with a jade plant knows this is fairly uncommon. I have had a few jade plants through the years that produced flowers but not very many. So whenever it happens, I get a little excited about it.

Jade plant flowers are white with a pink hue near the edges and are about 3/4 inch across.
Jade plant flowers are white with a pink hue near the edges and are about 3/4 inch across.

There seems to be no way of predicting when a jade will blossom. Lots of people, horticulturists included, have their theories about it. Some folks on the internet say they have it figured out. If that were the case, we’d be seeing truckloads of jade plants in the stores blooming just in time for Mother’s Day or Valentine’s Day — pick your favorite holiday.

Flower production in plants can be a complex proces. Before a plant can flower, it has to go through several steps before vegetative cells change into  reproductive cells, ie. a flower bud.

A basic principle in botany is that a plant, like most other organisms, will not reproduce until they reach maturity. One familiar example of this is an apple tree which might not bloom for six or eight or even ten years.

We forget sometimes, that our houseplants’s ancestors originally grew out in the wild with no help from people, thank you very much. Jade plants belong to the genus of plants called Crassula. Many Crassula species go through an annual a rest period in their native habitat. In their part of the world, the rains stop for a while and the Crassulas  go into a rest period. It’s critical for the Crassulas that the humidity falls to an arid, desert-like condition during this time.

Once the dry period is over, the plants resume growing and that completes one lifecycle. So, to induce flowering, it would make sense that we try to reproduce those types of conditions found in the wild.

OK, so here is my theory of the erratic flowering of jade plants. Many gardeners or houseplant fanciers love their plants and don’t want to hurt it, I don’t blame them. So they keep watering and feeding the plant all year ’round which keeps the plant in a continuous growth stage. The jades never get a chance to rest and they never get a chance to complete a full annual life cycle. This either delays maturity or fails to trigger the reproductive response.

Many factors are involved in stimulating plants to flower: fertility, moisture, intensity of sunlight, length of daylight, temperature extremes both warm and/or cold, length of time exposed to temperatures, air movement, insect damage, and others. The timing of all or any one of these factors can determine if and when a plant will bloom. Some easy-blooming plant species will bloom despite not growing in ideal conditions. Others, like jade plants I’m guessing, require a more complex sequence of events in order to produce flowers.

All that being said, I have noticed that jade plants are more likely to bloom is they are slightly pot-bound. So does this mean that the plants have been growing long enough that they’ve reached reproductive maturity? Or does crowding their roots induce flowering? Maybe sometime in the future a budding horticulturist will discover the secrete.

Bob

 

 

Flowers on elephant ears — colocasia

I’ve been growing Elephant ears — Colocasia esculenta — for many years. Over that period of time I’ve rarely had them bloom. They just don’t set flowers very often.

Normally when plants blossom, it means they are all set to produce seeds. Colocasia, however has been cultivated for so long, that it no longer is able to produce seeds and relies on people to reproduce. In tropical regions, people plant the underground corms like we would plant a flower bulb here in Michigan.

Colocasia is a dramatic addition to the landscape with it’s huge leaves that easily grow to three feet long in Michigan. In it’s native area in the tropics the leaves can measure six feet in length.

People in the tropics don’t grow them for their landscape, instead they eat them. There, colocasia is called taro and is a major food crop where it is used like we use potatoes here. Millions of tons of taro are harvested each year.

One winter, many years ago, I had a recent immigrant from the south Pacific visit the greenhouse where I was growing dozens of colocasia in pots getting them ready for planting out into the landscape. She recognized them immediately and asked me if I was growing them for harvest. I told her they were for planing out in the landscape as a decorative plant. She laughed and thought that was quite funny!

 

The flower bud on my colocasia is ready to open.
The flower bud on my colocasia is ready to open.

My blooming colocasia was one that I stored in my semi-heated garage over winter. I kept it in its pot and let the soil dry out. I watered it once in a while.

The plant went dormant and was exposed to some cool temperatures for extended periods of time but it never got much colder than the lower 40’s. The only light it got was low, indirect sunlight from a small garage window.

I have a theory that stressing the plant somehow triggered a flowering mechanism. The other colocasia I had bloom was about 12 years ago and that plant was stored over winter much the same way.

I’d be interested to hear if any readers have had similar experiences with their colocasia.

Bob

Lemon tree recovering from frosty fall temperature

Sometimes gardeners are given plants that others can’t use or take care of but they just can’t bare to throw out. That happened to me this past summer when someone gave me a four foot tall lemon tree. It was in mediocre condition, a little weak and run down and needed some extra attention.

I re-potted it and applied slow release fertilizer pellets. Once or twice a week it also got a dose of manure tea solution.  It took me the rest of the summer to nurse it back to reasonable health.  And it actually looked pretty good going into the fall.

I always like to keep my citrus trees out as long as possible in the fall. It seems like a bit of a chill tends to make them a little more hardy. I don’t worry about the trees if it gets down below freezing. They seem to do well even when it briefly dips into the upper twenties at night.

One evening this fall I got caught stretching the season out too much. The overnight temperatures were predicted to be around 28°F so I moved the trees to a sheltered area near the garage, tossed a light frost cloth over the top of them and let them stay out that night.

The actual temperatures were almost ten degrees colder than predicted. The oranges looked a little droopy from the cold but I was pretty sure they would pull through. I’ve seen them handle some pretty cold temperatures after a power outage. The new lemon tree however, lost nearly all of its leaves. A large percentage had already fallen off of the tree and were laying on the frosted ground — it did not look good at all.

That day I moved them all into a semi-heated area in my garage for storage. The temperature stays in the upper 40’s and the trees get a few hours of winter sunlight from south facing windows.

 

These buds started out as just tiny green bumps. Here they are about a quart of an inch long.
The new buds grow from the node where the old leaves used to be.

A couple of days after Christmas I noticed some tiny green pointed buds here and there on the lemon tree — it was still alive and wanting to grow leaves! A few days later, buds were emerging from branches all over the tree.

This week, the buds are still growing and developing into new leaves and twigs.

Right now the largest new lemon twigs are about one and a half inches long.
Right now the largest new lemon twigs are about one and a half inches long.

I’m fairly optimistic that the lemon tree will completely recover but it’s not out of the woods yet, we still have plenty of winter left before spring arrives.

Bob

 

 

Taking care of your holiday rosemary plant

Although nowhere near as popular as poinsettias, rosemary plants are becoming a favorite holiday plant.

Rosemary trimmed to a conical shape bears a striking resemblance to a miniature Christmas tree. Though it may look like it, rosemary is not related to pine, spruce or any other evergreen trees. It belongs to the mint family of plants which includes basil, thyme, mint and sage.

Just brushing against the leaves of  a potted rosemary releases its signature fragrance that can fill a room.

In most cases, fresh sprigs can be cut from a potted rosemary and be used in recipes calling for this herb. I say in most cases because sometimes plant growers apply systemic pesticides to their rosemary crop. In that case the rosemary is intended for ornamental use only and not for consumption. Always read the plant tag before assuming your plant is OK to use in the kitchen.

 

Plant tags often contain more information than just the name of the plant.
Plant tags often contain more information than just the name of the plant.

Don’t be tempted to water your plant and let water stand in the saucer or wrapper thinking that will supply even moisture. Standing water will drown and kill rosemary roots and eventually the entire plant.

On the other hand, don’t let the plant dry out. The stiff foliage doesn’t appear to wilt much when the plant gets dry, but damage can happen pretty quickly from lack of water.

Place your rosemary into a container of water and allow the entire root ball absorb water.
Place your rosemary into a container of water and allow the entire root ball absorb water.

Try this little trick: try to gauge how much your rosemary weighs before you water it. After the plant has drained in the sink, note how much heavier it feels when you pick it up. After a few times you’ll be able to have a good guess at how dry the plant is. If you’re not comfortable doing that, use a moisture meter — they’re relatively inexpensive and make a great Christmas gift!

Finally, be sure your plant gets as much direct sun as possible — a south window is almost mandatory. We’ve been setting ours outside during these mild days to help the plant get more sunshine.

Bob