Sunflowers cause problems in garden

Plants have developed an number of different survival techniques that can give them advantages over other plants competing for the same growing space. For example, some plants have roots that produce chemicals that inhibit the growth of other nearby plants of other species. It’s a process known as allelopathy.

Black walnut trees are probably the most recognized allelopathic plants. Homeowners find that it’s impossible to grow many kinds of plants in the root zone of a black walnut tree. Although they work differently than black walnuts, many farm crops such as alfalfa, buckwheat, winter rye and others are alleopathic plants.

Sunflowers provide a wonderful backdrop in the garden as they tower over a space making them a favorite of many gardeners. What gardeners might not know is sunflowers are also alleopathic plants. Because they have the ability to suppress the growth of weeds, sunflowers and other plants are the subject of on-going research to develop organic herbicides for use in sustainable agriculture. Unfortunately, along with weeds, many kinds of garden plants are affected by sunflowers as well.

Tomatoes struggle to grow under sunflowers.

Until you know which of your plants can tolerate growing near sunflowers, the best thing is to grow them in a separate bed away from other garden plants.

Bob

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Pruning milkweeds

I saw my first Monarch butterfly several days ago. I know they were here much earlier because I found a caterpillar on my milkweed plants. That means there had to be a female butterfly around before that.

It takes around four days for a Monarch egg to hatch. The caterpillar stage lasts around a week and a half to two weeks. Since my caterpillar was almost fully grown, the female Monarch that laid his eggs arrived nearly two weeks ago. How did she sneak into the yard without me seeing her?

This monarch caterpillar has by now formed a chrysalis.

Most of my milkweed plants are on the verge of blooming. The plants are maturing and the leaves and stems are beginning to stiffen and get tougher in order to hold up the flowers and seed pods. Although female Monarchs will lay eggs on any milkweed, they prefer the more tender leaves toward the top of the plant.

A gardener I know suggested that I cut back my some of my milkweed plants to stimulate new growth and leaves. Theoretically, those new leaves would make my plants more attractive to the butteries than others in the area. I just snipped off the plant just above the existing leaves. That caused some milkweed sap to ooze out of the cut. That sap is poisonous and irritating so make sure you don’t in your eye.

Cutting the milkweed just above the leaves allows secondary leaf buds to sprout and grow.

This is the first time I’ve tried this with milkweeds. I’ll let you know how it turns out.

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

Different approach to controlling field bindweed

I came across an old publication about dealing with weeds in farm and garden situations. The author discussed why weeds grow where they do and how we can use that knowledge to reduce weeds naturally without the use of herbicides. Needless to say, that is a large and complex topic, too big to go into detail here.

One item that did jump out at me was a unique way of killing field bindweed.

Field bindweed is one of the most tenacious weeds we have in the garden. If you have ever had a bindweed infestation in your garden, you know what I’m talking about. It grows from a net work of underground roots that will grow several feet deep and have a lifetime of twenty years or more. I’ve blogged about this weed in the past.

Even after being cut back all season, this field bindweed still managed to push its way through mulch.
Even after being cut back all season, this field bindweed still managed to push its way through mulch.

Other than using chemical herbicides, the traditional way of controlling bindweed is to starve the root system by cutting back the tops whenever you see them. That may mean as often as every few days or so, especially early in the season. By cutting back the tops, you remove the leaves stopping all photosynthesis. That forces the plant to use stored energy as it sends up new shoots. Eventually, the plant runs out of energy and dies. That process may take a few years.

The author of the weed publication offers a different take on bindweed. He mentions, almost in passing, that dahlia roots secrete a substance that kills field bindweed. I’ve been trying to think back to all of the hundreds or even thousands of dahlias I’ve grown in the past and can’t seem to recall ever seeing bindweed growing with dahlias. I’m not growing dahlias this year and have not grown them for several years.

You would still need to control other weeds in your dahlia area.
You would still need to control other weeds in your dahlia area.

If the dahlia vs bindweed theory is true, that gives gardeners a new ally against this noxious weed. It would mean taking a piece of ground out of normal production and growing dahlias there for a season, which would not be all that bad of a thing I suppose.

Growing enough dahlias to cover a large area presents a whole new set of challenges. That is a topic for another time.

Bob

Downton Abbey roses for your garden

I was a late comer to Downton Abbey, it wasn’t until season four that I started watching the series. That’s when my wife insisted I watch a a couple of episodes — I was hooked from that point on.

Of course after that, we watched a marathon of all the past shows so I could get up to date on everything and my wife could watch a couple of episodes she missed.

Now that we know that there is nothing but blue skies ahead for all of the characters, what’s next?

The producers of Downton Abby have teamed up with a highly respected California rose grower, Weeks Roses, to develop a line of roses based on the television series. The roses have names that will immediately invoke an image: Anna’s Promise, Pretty Lady Rose, Edith’s Darling, Violet’s Pride.

Week’s Roses is a grower and wholesaler, that means they don’t sell directly to to public. The good news is that the roses are readily available from local garden centers and online sellers.

How about that Edith? She’s a marchioness now!

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

Moth mullein welcome in the garden

There’s some new unexpected members to our garden family of plants this year. It is a group of moth mullein plants.

I’m not really sure how they got there. I figure they most likely hitched a ride as seed in soil from some other plants that I transplanted from someone else’s garden a couple of years ago.

Since moth mullein is a biennial, it takes two years to bloom. The first year for all biennials is a nondescript growing stage which is why I hadn’t noticed the mulein until now. If I was a more tidy gardener, I probably would have pulled them out last year thinking they were some kind of weed seedlings.

Moth mullein is a non-native species so, many people consider them actual weeds. Originally they were brought to this continent as a decorative flower and useful herb — it has some insecticidal properties.

Moth mullein in bloom.
Moth mullein in bloom.

While it may be an immigrant to this country, moth mullein seem to have very little impact on the native ecosystems of our area. They really can’t compete with well-established native plants. However, each plant produces thousands of seeds a year and tilling the soil tends to stimulate their germination. In the garden they may eventually wear out their welcome. In some states they are classified as noxious weeds but not here.

American goldfinches feed on the tiny moth mullein seeds. I saw a pair of goldfinches checking out my plants today. The seeds are not ready yet, so they decided to leave before I could get a photo of them. The seeds are pretty small, about one millimeter long, and can sprout even after laying for a hundred years.

I’m not too worried about the mullein taking over my garden just yet. They are behaving themselves in a very dry flower bed and are only a couple of feet tall. In your garden, if it has fertile soil and is well watered, they might grow twice that size.

Moth mullein is a perfect candidate for an English cottage garden where plants are expected to reseed themselves year after year.

Seeds are available through mail order seed catalogs and online sellers. Of course you can always collect some from the wild since they are not endangered nor invasive in Michigan.

Bob

Easy to grow iris give plenty of color

Iris are one of my favorite flowering plants for a number of reasons but mainly it’s because they are so easy to grow compared to some other plants. I’m not the only that knows this which is probably why you see so many irises in gardens.

Although there are several types of irises, the one that everyone thinks of when you say “iris” is the bearded iris sometimes called German iris. Irises put on quite a show in return for comparatively little effort on our part.

Iris

Irises are perennials, which means plant them once and they’ll come back again year after year. They are very resilient plants and are quite cold tolerant. Ours when un-mulched, came through two extremely cold winters and never missed a step.

Bearded irises require well-drained, sunny locations to thrive. Soggy soil, especially during the summer, will cause their roots to rot. On the other hand, they need plenty of water during the early spring, shortly after they wake up from their winter dormancy. Around here, we usually get enough rain in the spring for them to be satisfied.

The most common mistake beginners make when planting iris is to place them too deep into the ground. Only the bottom two-thirds of the root rhizome gets covered with soil. The other on-third is above ground as I heard someone say, “like an alligator”.

German irises grow so prolifically that they will over-crowd themselves over time. So, every three or four years they need to be dug up, divided and replanted. It’s a relatively easy thing to do and you don’t have to worry much about hurting the plant. I’ll discuss this in a post later on this summer as we get near thinning time.

Bob

Start a new tradition throw a daffodil party

Are booming daffodils a good excuse for throwing a party? It is if you are Dick Deionne of Ann Arbor.

Each spring he throws a daffodil party where he treats his friends to the spectacle of thousands of daffodils that includes dozens of different varieties.

Beginning gardens should  be aware that daffodils are planted in the fall.
Beginning gardens should be aware that daffodils are planted in the fall.

Most of his plantings are under trees or around the edges of the wooded areas.

Daffodils thrive in rich woodland soil.
Daffodils thrive in rich woodland soil.

Normally black walnut trees are troublesome for flowers because of a poisonous chemical that walnut roots release into the soil. This makes the area in the tree’s root zone unsuitable for most plants. Daffodils are resistant to the chemical and do well under black walnut trees.

Daffodils grow happily under black walnut trees.
Daffodils grow happily under black walnut trees.
A few daffodils in the garden are nice but a planting like this makes quite a statement.
A few daffodils in the garden are nice but a planting like this makes quite a statement.

If you want to start your own version of an annual daffodil party, keep in mind that daffodils are planted in the fall. Flower bulb sellers start taking orders for daffodil bulbs in mid-summer for fall delivery.

Bob

 

 

Super-sized Christmas poinsettias are started now

Holidays for horticulturists usually have two dates.  First, there is the actual date that the holiday occurs. The second date is the time when plants associated with that holiday need to be started.

Greenhouse people are beginning to make preparations for Christmas now, in very early spring .

I’m sure you’ve seen giant-sized poinsettias in full bloom during the Christmas season. Did you ever wonder how they managed to get them so big? The secrete is to keep the same poinsettia plants growing year after year.  Each year the plants get bigger and produce more colorful bracts.

If you have a poinsettia that is still alive from Christmas, you can renew it and have a larger more colorful plant for next Christmas.

 

A bench of pruned poinsettias at Matthaei Botanical Gardens, Ann Arbor.
A bench of pruned poinsettias in Greenhouse 3 at Matthaei Botanical Gardens, Ann Arbor.

Start by pinching off all of the leaves and bracts from the plant. Many of them may have already dropped off anyway by now. Next cut the main stem or stems to about six to eight inches above the soil surface. Remove the plant from its pot.

This pruned poinsettia is just beginning to make new growth.
This pruned poinsettia is just beginning to make new growth.

It’s best to carefully rinse the old soil off of the roots and re-pot the plant using new potting mix. Removing the old soil is not absolutely necessary though, I’ve had very good results by simply leaving the existing soil then re-potting into a larger pot. What is necessary however, is using a loose commercial potting mix, not soil from the garden. Poinsettias need loose soil, no ifs ands or buts.

Then water thoroughly — soak the pot with water and let it completely drain out. Never let poinsettias sit in the water that collects in the pot saucer, they just can’t tolerate wet feet.

Put it in the brightest area you have to encourage it to grow. Once you see shoots developing, feed it with a good house plant fertilizer about once a month.

Later, after the danger of frost has passed, place the plant outside in a bright spot that has dappled shade during the hottest part of the day.

As the plant grows through the summer, you can pinch back shoots to help keep a symmetrical shape. Pinching will also stimulate more branching giving the plant a more compact and bushy look.

With some care and luck you’ll have a stunning plant to show off next Christmas.

Bob