Monday, June 19, 2017

Proper Pruning Protocol

Deadheading Dwarf Korean Lilac

The daily June $64,000 question for garden center horticulturists is: Why didn't my ___________________ (forsythia, lilac, hydrangea, spirea, weigela) bloom this spring? If you dropped more than one species on that blank line, read on to get a handle on what's amiss in your shrub border, and get a leg up on flowers for next year.

Certainly there are a lot of possible answers to the why-didn't-it-bloom question:
  • Too much shade (for a sun-loving shrub)
  • Plant too immature to flower
  • Previous year the plant was heat or drought-stressed
  • Inadvertent exposure to high nitrogen lawn fertilizer formulations flung into beds with rotary spreaders. Lots of yummy nitrogen will often create a let's-grow-leaves-and-forget-the-flowers state.
  • Plant is in a "happy hole". For the uninitiated (and that's everyone since I just made that up), a happy hole is a site where everything is so-o-o perfect the plant is locked into a leaf-growing hormonal state, rather than a reproductive (flowering) one.

Another possibility mustn't be overlooked. How about - The shrub was simply pruned too late the previous year. This is so logical you're likely to take your open palm and slam it against your forehead as a cartoon cloud light bulb appears in your mind.  

Here's the golden rule for pruning flowering deciduous shrubs. If it has a conspicuous flower (to me that means large enough that it's considered a seasonal attribute), and it flowers before July 1, it's a spring bloomer. Spring bloomers flower on stem growth made last summer. So, it makes sense the plant should be pruned within four to six weeks after it blooms. Four being better than six, if you're asking. That gives the plant all summer to produce the stems that will flower the following spring. If you (or your gardener) prune these spring flowering shrubs too late, say July or later, your'e cutting off next year's potential flowers. Didn't I tell you it's so explicable. A sampler of spring bloomers that would fall in the above category: deutzia, forsythia, lilac, mockorange, weigela, to name a few.

Pruning Lilac after bloom


Conversely, those shrubs that bloom their hearts out for you after July 1 are flowering on the growth they made in spring- April, May, June. So, you can prune and shape them EARLY as they're coming out of dormancy, just showing leaf buds. Don't wait to trim them later in the spring, say May or early June, as you'd be eliminating or pushing back potential flowering branches. Some favorites that fall in the summer bloom category are: hydrangea, potentilla, rose of Sharon.

April-pruned Hydrangea = July flower buds

There are a couple of ringers in the viburnum and spirea clans. Because they are such broad genera they have "family" members that bloom in spring, some in summer. Therefore, each species or variety should be researched and pruned on a case-by-case scenario.

Proper pruning protocol, like so many things in life, is all in the timing.

Same species: Properly pruned vs. not

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Sunday, June 4, 2017

Potting Techniques - 200 Level Course

As I was making containers yesterday I realized I'd never written a post about just that. What are some of the tips I've appropriated from others over the years, not only to make the potting process easy and fun, but to ensure the plants grow successfully?

1. If you need height for your focal point plant (say that five times fast) mound the potting soil in the center. It can even be higher than the edge of the pot as long as you taper the soil dramatically so it's well below the rim ate the edges. As you might expect this keeps the soil in the container, not on your patio, after the first watering. I've seen only one person do this over the years and it gave her pots dimension and drama from Day 1.

2. Drop-potting is my favorite trick. Fill your decorative container with soil to the depth of the deepest plant pot. Place that empty pot in place, proceed to fill around it until the soil level is at the depth of the bottom of the rest of the of the pots. Fill in and around these empty pots with potting soil. Use your fingers to       tamp in and around the pots. Pull one empty pot out at a time and simply plug the desired plant in its new home! Once the plants are in place it's a simple matter to gently firm the root ball into even better contact with the surrounding soil. This makes potting so much easier. This is especially true for plants that have leaves and stems close to the ground that are easily broken with traditional "backfilling" of soil. Hopefully, the picture will solidify the concept.


3. If you have vining/cascading plants, and who doesn't, angle those empty pots with the tip at the edge of  the container. Planting at this angle will expedite the vine's bungee drop over the side. Notice how the pot at 6:00 in the pic is tilted at the edge, rather than flat like its neighbor. Cunning, huh?




4. If you have heavily knotted root systems don't be afraid to tease apart those sections with the heaviest tangling. Don't be shy, you won't hurt the plant unless you tear all the soil from the root system.


5. Occasionally we use tropicals as focal points in mixed containers. Know that certain tropicals bloom best   when pot-bound, and are therefore "stressed". Examples would be: Agapanthus, Bougainvillea and Hibiscus. So, taking them from their grower's smaller pot and placing in a much larger soil mass may give them too much freedom. Your reward for this generosity is a plant that changes its goals to growing roots at the expense of flowers. What you might do is faux pot by simply placing the plant, still in its plastic grower's pot, into your container with the lip even with the finished soil surface. Attention please, this will mean you will water that plant-in-pot-bondage more, but the increased bloom will be worth it, I promise.

6. No matter what your potting soil bag says about "fertilizer added" it ain't enough. Standard potting mixes are overwhelmingly peat or bark-based so there's virtually no innate nutrient value. Every time you water nutrients are leaving exiting the pot via the drainage hole. For that reason it's important to fertilize consistently - less for plants in shade than sun, though. If you're that busy person that isn't going to use a water soluble fertilizer every two weeks, then at the very least add a time-release fertilizer (like Osmocote that feeds for 4 full months) at planting. The takeaway is feed your plants regularly throughout the growing season.

One last tip, consider shoving the plant tags down in the middle of the container. That way when the compliments pour in from envious family and friends, and you draw a blank on what Angelonia variety you used, simply pull out the tag and share. Now who's the cunning one?  



    











            

Monday, May 15, 2017

The News on Boxwood Blight


Lesions are the first symptom (via Rutgers University)
As a hortiholic, I love to write about the many fun, positive aspects of horticulture. I like to share cool new plants or things I've learned over decades to help other gardeners become more successful. Every once in a while something comes along that isn't so much fun, but deserves attention. Boxwood blight (caused by the fungus Calonectria) falls into that category. It's important to understand this isn't the end of using boxwood, but another manageable disease.

Lesions progress to this (via U of Illinois)
Backstory for those that haven't heard the latest? Boxwood blight may have been in the U.S. for a few years before it was confirmed in 2011. It has now spread to 22 states. Illinois joined that less-than-elite group with two confirmed cases in northeastern Illinois earlier this year. The fungus starts with brown/black round spots (see above) that generally run together darkening the entire leaf (right). Rather quickly the plant will defoliate leaving bare stems. These stems will show elongated black streaks on the bark (below).


     
Note black streaks - final stages
We need to show restraint in jumping to the conclusion that any boxwood malady is the bad disease (cue the spooky Halloween music, heavy on the organ). There's confusion as there is another irritating, but not fatal, disease call Boxwood blight (caused by Volutella) that's been around for years. So, we need to be careful when we use the term "Boxwood blight". Volutella does not exhibit the black stem streaks or defoliation of the plant.

The final stage


There's also an insect, Boxwood leafminer, that can cause browning of leaves (that could be confused with Calonectria). Leafminer is easily controllable.

Example of Leafminer damage

As an average homeowner with even a few plants, what can you do to protect your boxwood?

  • Like life, education, not hysteria, is the key to success. Learn the symptoms of Boxwood: leafminer and the two very different blights.
  • If you have an irrigation system consider reducing the frequency of watering zones inhabited by box. This blight is spread not by insects or wind (this is great news, people), but by splashing water on an infected plant. Established box isn't water needy and doesn't require "dampening" for 5-10 minutes in the middle of    the night three times a week. You don't want to get the Hortiholic started on the subject of improper use of    irrigation systems. How much better to water deeply, but infrequently. 'Nough said?
  • Mulch to reduce splash. Early indications are that mulch may reduce the splash of spores onto lower leaves, thus reducing the likelihood of infection.
  • Don't prune or work in and around your boxwood early in the morning when there's dew on the leaves or anytime the foliage is wet, especially in humid weather. Again, this is a fungus that requires moisture to infect its host.
  • Can you live with a less formally pruned geometric shape? A "looser" plant that's not so tightly sheared will    allow better air circulation, drying the foliage more quickly, reducing the opportunity for the blight to infect.
  • If your boxwood has symptoms wait until the plant is dry, cut a sample that includes a significant portion of stem (not just a few leaves) and place it in a double plastic bag. Hygiene is a good thing. Seal completely and bring it into Plant Health Care. A picture or two showing the overall appearance of the plant is an extremely helpful addition to the physical sample. Again, at this point chances are overwhelmingly against your plants being infected with Calonectria.
  • When adding boxwood to your landscape be sure to deal with reputable nurseries and garden centers that know plants and adhere to established boxwood cleanliness programs. Chalet, for example, has separate written protocols for handling boxwood for our: retail store, landscape division and growing nursery in Wisconsin.

Like people, all plants can have "issues". This newest Boxwood blight should be considered a manageable disease. After all, try to name even one substitute plant that does everything boxwood can do. There are a lot of reasons it's worth using.




Monday, April 10, 2017

Spring Annuals.... No Non-scents

I offer my sincere apology to Mrs. Ogden, my eighth grade English teacher, for the above double negative. More simply put, I want to share some beautiful, cold-tolerant spring annuals that also bear the gift of fragrance. Who doesn't like two for one?

Beware sniff-test shopping on a cold spring day and understand that you won't be getting an accurate scents (unforgivable, but I've no pun shame) of fragrance. It will always be stronger on a dry, sunny day when temps are warm. Some deliciously scented spring annuals to tickle your olfactory organ:

* Alyssum - Also called "sweet alyssum". Unlike many of the cold-tolerant, short span spring beauties this workhorse goes the distance season long until the big fall freeze. Bonus points! Really a blanket-flat, ground cover annual 3-4" tall, growing 6-8" wide. Color range has been expanded from granny's white, purple-ish and pink to include strong violet, rose and even apricot. Whites tend to have the strongest aroma.



While it will cascade in containers, it may be underwhelming as the growing season progresses and it's steam-rolled by taller, beefier neighbors. I love it for front of window boxes and in-ground as an edger. Will tolerate light shade (note tolerate, not prefer), but not water-logged soils. Do get out the scissors and shear back declining flowers after each wave of bloom to keep the flowering encores coming. Just don't be overzealous and scalp to the ground...

* Dianthus - "Annual pink" shouldn't be confused with its biennial cousin, Sweet William (Dianthus barbatus). Like alyssum, not just a one-shot spring wonder, but will bloom all season, especially if it's a cooler summer, or they're sited in some afternoon shade when it's H-O-T. Well-drained soil. Gorgeous shades of maroon, purple, red, pink, white, and killer combos thereof. Great in beds or containers. Those who deadhead will reap the rewards of their labor.

* Pansies & Violas are already a fragrance "given" for those that read the last post, "A Pansy Primer".

* Stock - A florist flower fave for decades. Scent is generally touted as spicy clove. Flowers can be double or single, clustered in short spikes on plants ranging from 12-18" tall. Colors are: pink, white, rose, antique cream and purple. Foliage is gray-green. While they shouldn't be exposed to frost/freezing weather, they stop performing when daytime temps rise and stay about 75 degrees F. Stock can have a 7-10 day vase life, which is a long time as cut flowers go. For those that love to dry flowers, stock is a great candidate. They can be grown from seed, but you'd better start early to have sizable plants to transplant in early spring. Better to buy larger, budded plants, I'd say.   



* Sweet pea (annual) must be grown by anyone that loves sweetly fragrant pastel flowers. If Heaven has a fragrance, it must be "sweet pea" (one man's opinion - mine)! The scent is unlike any other flower, light, distinctive and unforgettable. It's a grandma flower, for sure, and that's part of its charm. I think it's gotten lost for a couple of generations as it doesn't transplant well. It also doesn't have much sales appeal as a leaning green baby vine in a 4" plastic pot. Therefore, sweet peas should be seeded directly into their final resting place, or in peat pots that can be broken down without disturbing the skinny root system. Soak the seeds overnight or nick with a nail file to break through the tough seed coat to speed germination.



Sweet pea is a cool/cold season vine that need a trellis or support to grow around and through to be upright. Keep cutting the exquisitely scented flowers to bring in the house - Heaven-on-a-stem! The more you cut, the more they'll rebloom until it gets hot. Then they're finished (like stock and many other cool spring annuals).

Ladies and gentlemen, it's spring, dust off your trowels!      
     

  

Friday, March 24, 2017

A Pansy Primer


If you haven't planted pansies or violas to jump start your spring garden you're robbing yourself of weeks of additional color. And no matter how mild March might be there's precious little color to be had before April in a Chicagoland garden, and that includes bulbs. Cue the pansies and violas, center stage.

While pansies and violas are in the same genus and species (Viola x wittrockiana), here's an admittedly simplistic differentiator. Violas are essentially small-flowered pansies that bloom more profusely than pansies. Those wanting to quibble should find a taxonomist that cares. Here's why they're both worth the effort:
  • Between the two, the color range is phenomenal. Blues in all hues, purple, yellow, orange, apricot, white, black (like Black Angus black, seriously), maroon, and many combinations thereof. It's a stretch, at least for me, to say there are true reds and pinks. The reds run more to maroon. The pinks are more rose shades. But the color range challenges petunias, which almost cover the rainbow.
  • The flower "faces" are intriguing. There are monochromatics that are pure, deeply saturated colors and beautiful jewel tones, too. There are interesting blotched pansies. There are bicolor and tricolor combinations. Some have striped veins that look like cat whiskers. Some of the newer series produce flirty, ruffled flowers.
  • The monochromatic orange, apricot, yellow, and white pansies often have light, but wonderful fragrance when temps are warm. The aroma reminds me of apricots for some reason.
  • With appropriately scaled small vases with narrow necks, they make sweet, long-lasting cut flowers. It's nice to appreciate the colorful complexity of the often intricate "faces" up close and personal.
  • They tolerate cold as well as they love "cool". While they don't laugh aloud at freezing temps, they certainly do scoff. If they've been hardened off (that is, acclimated to cold outside for a number of days at the growers) before shipping, they can survive being encased in frost or snow. When the sun melts the snow they'll return to an upright position. No harm, no foul. How many annuals can claim that?
  • Whether you need early color for hanging baskets, window boxes, containers, or beds, pansies and violas can do it all. They're especially nice in the foreground of beds, fronting the uninteresting ankles of taller tulips, daffs and newly emerging perennials.
Culturally, what do they ask in return for all this garden gorgeousness? Not much. Pansies and violas dislike heat and humidity equally. So, site them in full sun and enjoy the spring show until the temps start pushing 80 degrees. When they start getting "stretchy" and lax about reblooming, think "Discard" and move on to your summer crop of heat-tolerant annuals. Or, if you want to stretch the return on your spring horticultural investment, site them in an area where they'll receive afternoon shade when it gets warm. You'll squeeze additional weeks of bloom from them with that trick.

Keep pansies and violas evenly moist, especially as day and night temps remain elevated. The other recommendation is to deadhead. Timely removal of spent flowers really resets the bloom button and keeps the show going. Then there's feeding. While they're not particularly conspicuous consumers an application of a timed-release fertilizer at planting time, or several applications of a high phosphorous (P= middle number in a 10-15-10 analysis) water soluble product during their springtime with you will make a world of difference in bloom performance.

A few noteworthy series:

'Spring Matrix' - Large-flowered, perform well early in the cold, often sun-free conditions of spring.
Spring Matrix photo courtesy PanAmerican Seed 

'Imperial Antique Shades' - Huge flowers, in romantic apricot to rose shades.
Antique Shades photo courtesy Clesen Wholesale

'Cool Wave' - Trailing 18" or more, so great for baskets and tumbling down the sides of larger containers.
Cool Wave photo courtesy Ball Horticulture
'Fizzy' - Beautifully frilled and ruffled, often with picoteed edges. Many variations on the purple and yellow theme!
Fizzy Lemonberry courtesy Clesen Wholesale
Oops, I forgot to mention the flowers are edible - great as a garnish or to color zap a salad. Honest. Pass the pansies, please.
      

























            

Friday, February 24, 2017

Winter Warmth Woes for Plants


While 65 degree winter temperatures in Chicago, day in, day out, are cause for jogger jubilation this weather is not doing most of our plants any favors. Our perennials, bulbs, shrubs and trees are being set up for a potential world of hurt. A notable exception is the lovely, naturally early-blooming witchhazel pictured above.

May I set the stage? December was seriously cold. The ground froze early and we had good snow cover to keep it frozen. Great. Now we've had less than 1" of snow in the new year. The soil surface has thawed. We've had minimal rain to provide moisture for roots. Is there anything we can do to lessen the potential damage to our plants? For what it's worth, here's my take on the situation.

Not ready for prime time
Bulbs
Unfortunately, bulbs are making an early above-ground debut. This is most apt to happen in unshaded south or west-facing exposures against buildings. The reflected heat has warmed the soil and led bulbs to believe it's time to rise and shine. Bulbs have built-in insulation mechanisms so leaves and unopened flower buds can tolerate very cold temperatures without damage. Open flowers would be subject to freeze damage. In other words, we're okay for the moment.
What to Do: If you want to be proactive apply an organic (I love leaf) mulch after the soil surface freezes again to keep it frozen to try to slow the bulbs down. Yes, that is an optimistic assumption.

Perennials
If planted in the past year perennials should be checked for "frost heaving". That is, the edges of the root balls would be 1/2" or more above the surrounding soil surface. Existing partially above grade these roots are subject to temperature and dehydration damage. Such plants are likely to pass on.
What to Do: GENTLY put a foot on either side of the EDGE of the root ball and try to push back into the ground. If dry, water those plants, then (leaf or compost) mulch when the surface refreezes. Remember, mulch roots, don't bury the crown (center) of the plant.

Water
Check plants, especially newly planted evergreens or plants in containers (ex: boxwood or Alberta spruce) for moisture. Dehydrated = damaged, dying or dead.
What to do: If the top inch or so of soil is dry, soak. When the soil freezes again consider applying mulch.

Water and apply Wilt-Pruf to crispy critters
Evergreens
Do you have broadleaf evergreens (rhododendron, azalea, holly, boxwood) in open, sunny windswept areas? Are they dry? If yes, did you water them?
What to Do: While temps are above 40 degrees F. consider applying an antitranspirant spray, Wilt-Pruf for example, to the underside of the leaves to reduce potential dehydration damage for the rest of the winter.

Tree wrap helps to prevent ugly cracks
Frost crack
Frost crack is a nasty symptom, occurring primarily on smooth-barked trees. If there's a prolonged period when trees are subjected to temps above freezing during the day, then dramatic drops at night, the expansion and contraction of the bark creates pressure points on the (again) south or southwest sides of the trunks. When the tree starts growing those pressure points may open up creating wounds - sometimes superficial, other times exposing deep fissures into the heartwood. Young (under 6" in trunk diameter): maple, honeylocust, sycamore and linden are most at risk.
What to Do: When the trunk surface is dry you might consider the use of the corrugated paper tree wraps or burlap to shade the trunk. Remove ASAP in the spring (mid-March).

Deer
Just because there's no snow cover doesn't mean our yews and arborvitae have a forage-free pass. On the contrary, I was inspecting my garden last week and saw 2 androgynous whitetails belly-high in the neighbors' yews, grazing. Two ear-splitting whistles later they were bounding down the street for a more relaxed dining experience. Very satisfying (for me).
To do: Consider draping the black mesh "deer netting" over yews or around arbs to exclude marauding deer. The netting isn't visible and really is a very effective deterrent. Or spray vulnerable evergreens with the repellent Plant-Skydd. It's also very effective when sprayed on emerging bulbs and dayliliesDeer just hate it!

Now the best we gardeners can hope for is a deep, soaking rain followed by a quick return to sub-freezing temps until the time when spring should really arrive.                



















Friday, February 10, 2017

Mid-Winter Houseplant Blahs

We're finally on the "backside" of winter. For those of us not winging off to a tropical island between now and spring that's an important psychological milestone, just as it is for our houseplants. Even the word "houseplant" sounds winter-weary and less than exciting - kind of like "leftovers". Just for today let's call houseplants indoor tropicals (ITs), and maybe they'll seem fresher.

This is about the time our ITs may be showing their ennui by exhibiting "symptoms". Certainly, they're as tired of short days with constant cloud cover and and low indoor humidity as we are. And that presumes we're watering correctly in response to these imperfect conditions. So, assuming they have good personal hygiene and are otherwise free of livestock and pestilence, here's an abbreviated troubleshooting guide. The caveat- "Probably" should probably be inserted in front of each bullet point. Why? Because it's as likely a combination of factors as a single one causing IT malaise in your collection.

Potato chip-crispy spots or lesions on leaves: Underwatering

Lesions that are soft, dark brown or water-soaked: Overwatering 

Leaves are curling (either upward or under): 
  1. Chilling (too close to a drafty window or door to the outside, room colder than the plant likes) and/or
  2. Overwatering
Leaf drop: 
  1. Plant subjected to temperature extremes (too high, too low) for some period of time
  2. Someone in charge of watering that let the plant go bone dry for weeks or months, and it's not a forgiving cactus or succulent?
  3. Is it a new adoptee that was just brought home from the greenhouse? In other words, has it been used to higher light and you've featured it in a window-less, light-less room resembling the inside of a sarcophagus?
  4. Did it get chilled on the way home by being outdoors unwrapped? Did it sit in a car while you shopped-'til-you-dropped for hours and the car temps got dangerously low?
Just tossin' these ideas out there. These aren't accusations, we're just trying to get to the root of your ITs problem (ignore unintended horticultural pun).

Lower leaves turn yellow and drop:
  1. If it's just one leaf and it's the very oldest (lowest on the stem) that may be okay. Leaves don't live forever. Plants naturally shed old leaves that are shaded by the upper portion of the plant.
  2. Multiple leaves yellow? Has it been overwatered? Too much water, too frequently?
  3. Chilling
  

Leaf ends or edges brown, brittle:
  1. Humidity just too low for the plant (by far the most common reason)
  2. Erratic watering- plant is alternatively wet and/or dry
  3. Like Goldilocks, room "too hot", "too cold", never just right
  4. Fertilizing frequently while plant is on winter growth hiatus, and therefore not utilizing nutrients. We call that "burn"
Lower leaves turn brown (dry) and drop: 
  1. Just not enough light for the species you're trying to grow
  2. Room excessively hot and dry
  3. Plant regularly underwatered
Individual leaf stems (petioles) or entire stems soft and mushy:
  1. Overwatered on a regular basis and/or
  2. Left standing in a water-filled saucer or pot with no drainage hole frequently and for long periods of time
White residue on soil surface:
  1. Fertilizing frequently all winter long? S-T-O-P now. Those fertilizers salts are accumulating because the plant is not growing and therefore not using them OR
  2. Using hard water with high salt levels
Plant not producing new growth:
  1. It's winter, full of short, cloudy days. Unless you have a greenhouse or full-length south or west-facing windows to maximize light to perhaps coax some growth from your plants, relax. This is normal for our winters. New growth should start peeking out as we approach spring.
Keep chanting the mantra, "It will be alright. It will be alright. It will..."      

          














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