New Plant of the Day: Cerinthe major

Cerinthe major ‘Purpurascens’
Family: Boraginaceae
Common name: honeywort
Origin: southern Europe, Mediterranean
Zone: 8-10
Size: 2’
Light: Full sun to part shade
Soil: moist, well-drained humus rich soil

I recently received this photograph from an old schoolmate of mine who could not identify it. It took me a little while but I was finally able to identify it as Cerinthe major. This is a new plant to me so I thought I would pass on the information I found.

The plant has thick blue-green leaves with white moddling. Small clusters of 1”-long nodding purple flowers form late summer and attract bees and hummingbirds. The tall stems curve like that of a shrimp, thus it is referred to by some as “shrimp plant”.

Start seeds indoors before spring and transplant outdoors after frost. Many have recorded that this plant self sows quite easily.

When to Plant Fall Blooming Bulbs?

(Crocus speciosus photograph courtesy of Sonja Keohane, all rights reserved.)

Question:
I just wanted to double-check a question about fall flower blooming. For fall-flowering bulbs like Colchicum autumnale, true hardy crocus varieties, and hardy cyclamen, can one plant now to get fall flowers because the flowers come up on the bulbs so quickly. Is this correct?


Answer:
I would say yes, this is a good time to begin your planning and planting of fall blooming bulbs. You are correct that fall blooming bulbs have a tendency to come up rather quickly, whether they are Colchicum, Crocus, or Cyclamen. The ideal is to plant roughly a month before the expected bloom time. Therefore late July or August is the appropriate time to plant. Some companies and seasoned individuals recommend getting started earlier, and the reason for that is to ensure that you get the bulbs that you want before it is too late. Because the selection of applicable fall blooming bulbs for our area is not as great as that of spring blooming bulbs, growers recommend buying early to make sure that your order is placed, processed, and shipped in a timely fashion. If you end up ordering and getting your bulbs too late you may find that the bulbs have already started to push their blooms before they have had the chance of being planted and establishing new roots. This may lead to a poor first bloom in your garden. To have the best chance of a decent bloom, plant your fall blooming bulbs in early August in well-drained soil and water during periods of drought.

Also, while we are on the topic, remember that most fall blooming bulbs put up their foliage in the spring, completely separately from the flower. The spring foliage is the bulbs chance to photosynthesize and store energy and carbohydrates for the upcoming fall flower. Many people forget where they planted their fall blooming bulbs and when the foliage comes up in spring they cut it back thinking it is some sort of weed. Then when the flowers emerge in fall, with diminished energy reserves, and the flower is less than spectacular people wonder why that is.

Therefore, order your fall blooming bulbs now and get them planted before the middle of August. Water them in times of drought and make sure they are in well-drained soil so that you do not run the risk of rotting the bulbs themselves. Lastly, if you fear you may not remember where they are planted, consider marking or mapping them so that you do not accidentally remove the foliage in spring. Enjoy!

Powdery Mildew on My Campsis grandiflora

Question:
My mature Campsis grandiflora is showing signs of a whitish/grayish film on some of its leaves. This has happened in the past, but never much before late September or October. Is this powdery mildew, or perhaps something else, and what might you suggest to eradicate it?

Answer:
Your situation does sound like a case of powdery mildew. Since it has been rather warm already this summer and with the few extremely heavy rainstorms we have gotten, it does not seem all that peculiar that the issue is affecting your Campsis earlier than usual. Campsis grandiflora is prone to powdery mildew but luckily these days there are cultivars being bred and sold that are considered to be more resistant. As you probably know from past years experience this fungal issue is not going to kill your Campsis, but the white film on the leaves is unsightly and does not help the plant as it tries to photosynthesize. The best solution that I have learned over the years is a homemade concoction that you use as a foliar spray. Add to a gallon of water two tablespoons baking soda and a drop of dish soap (Palmolive, Dawn, etc.) to give the mix a little viscosity. Once this is mixed, use it as a foliar spray and cover as much of your vine as possible. Continue to apply until the mildew seems to diminish. It may take a few applications over two or three weeks’ time. This usually does the trick.

Otherwise, think about the amount of airflow in the area where the vine is. Powdery mildew often occurs because of a lack of decent airflow, therefore pruning either the vine or other trees and shrubs in the area might prevent this from becoming such an issue in the future. My last thought is that Campsis grandiflora can be rather drought tolerant once established. Since you describe the vine as being mature then I would think you can cut back on supplemental watering at this time of year and hopefully the plant will still grow and flower well for you without the added powdery mildew.

Hibiscus in Nassau County, New York

Question:
I know I saw beautiful hibiscus decorative bushes in Nassau county last year. They were a pretty color, perhaps coral. I have been told the only hibiscus bush that would grow in our climate is the hardy hibiscus. I have looked on line under that topic and have not found the tropical looking - but cold weather hibiscus I so desperately want. Can you help me?

Answer:
There are essentially three different kinds of hibiscus that we commonly find here in the New York. One is a tropical shrub, one is a perennial, and one is a woody shrub. For future reference, when searching for plants or plant information, try and familiarize yourself with the botanical name of the plant. Knowing the scientific genus and/or species of a plant makes it much easier to find credible information, whether it be in a book or on the internet.

Hibiscus rosa-sinensis is a tropical shrub that is commonly sold as an annual in our area. They may be sold in shrub form or pruned up on a standard, a single trunk, to look like a small tree. They do have that large hibiscus flower and there can be lots of color variation, from white to yellow to red and every color in between. They are popular because with enough sun and water they can continue to bloom all summer long. They are not winter hardy, however, so come fall they will die unless you choose to move them inside to over-winter them indoors.

Hibiscus moscheutos, commonly called swamp rose mallow, is the plant most people call “hardy hibiscus”. It is a native perennial plant and does come back every year. This plant puts up skinny five or six feet tall stems with very large hibiscus flowers on top. Because it is a perennial, the duration of bloom is less than that of the tropical species, and they usually flower in late July or August. These plants thrive in full sun and very wet conditions, such as a low wetland or bog. Hibiscus moscheutos has very large flowers that are usually red or pink, but again, growers are introducing more color variation into the trade.

Lastly, there is Hibiscus syriacus, or rose-of-sharon. This is a woody shrub that is hardy to our climate and loves full sun as well. It is a very aggressive growing shrub that puts up many branches with grey bark and smaller hibiscus shaped flowers (perhaps two to three inches in diameter). This shrub also blooms later in the summer, but in full sun they can flower quite prolifically. These shrubs grow quickly and can seed themselves pretty freely around your property.

Red Nodules on My Maple in New York City

Question:
I have a very lovely Maple tree on my terrace. It is growing very well, beautiful leaves. However on the leaves there are tiny red nodules that are some sort of blight or insect. They don't move, but by seasons end most of the leaves have holes in them. The little red guys turn brown toward seasons end. The tree is healthy otherwise, and I would like to save it, but I cannot find out what this is or how to rid it from the maple. I have a fifty or so foot terrace, and this insect has not infested any other of the plants. If you can give me an idea of what this is and how to rid the tree of these "things" it would be greatly appreciated.

Answer:
Unsightly galls can be the work of many different kinds of flies, wasps, and mites. Because many insects only feed on specific hosts, knowing that it is a maple helps us narrow the options of what the insect is. Your description of the galls helps narrow the list down even further. The damage you are describing sounds like that of a gall mite. Eriophyd mites are microscopic mites that live and feed on many different kinds of trees and shrubs. Of the gall-forming mites, there are at least two that prefer to feed and live on maples, maple bladdergall mites (Vasates quadripedes) and maple spindlegall mites (Vasates aceriscrumena). The galls were describes to me as being more rounded than spindly, so I am going to guess that this damage is the work of the maple bladdergall mite.

As I usually do with insect queries, let me describe the life cycle and then recommended control. Adult mites over-winter on the bark of the maples. As the leaves emerge in spring the mites migrate to the fragile new leaf tissue and begin feeding. As they feed, the mites deform the plant cells and cause these galls to form. The adults burrow within these galls and lay their eggs. The larvae emerge, feed on the leaf tissue, and molt into adults in a few weeks time. The adults move on to feed and continue cycle. The galls are no longer used and usually turn brown.

The bad news is that these galls look unsightly; the good news is that this damage is not likely to kill your maple. Regarding control at this time, the only option is to remove the leaves that are heavily infested with galls. Physically removing the galls before the larvae can emerge will help control the populations. The next step is to take action the following spring. Use a dormant horticultural oil to coat the bark of the tree in spring before the leaves emerge. This oil will coat and suffocate the over-wintering mites and will help to diminish their populations before they get a chance to feed on the new leaf tissue. I would not necessarily count on complete eradication of the mites, but after two years of treatment you should find the populations to be more controllable and the damage to your maple less of an eyesore.

For this and other insect questions I refer to Garden Insects of North America by Whitney Cranshaw, available in our reference section here at the HSNY Library at 148 West 37th Street, 13th Floor.

Can I Grow Turf Grass in Planters?

Question:
I am hoping you can help me. I want to grow wheat grass for my indoor and outdoor planters. Every site I have searched gives suggestions on growing wheat grass for juicing and not ways of growing and maintaining. Is there a way of maintaining wheat grass so that it lives longer than the 3-4 week period these sites suggest?
And is there possibly another plant/grass that has the same look and appeal of wheat grass that is easily maintained?

Answer:
Thanks for writing. As you have researched, my personal experience is that wheat grass does seem to lose it’s vigor after about a month or so. Even though I have not tried this myself, I believe that there are other turf grass species that you might be able to grow successfully in containers by providing standard turf maintenance.

Most bags of turf grass that you will find in garden centers have a mixture of three different turf grass species: bluegrass, fescue, and ryegrass. More and more companies are developing shade tolerant bluegrass species, but one thing remains the same, bluegrass takes a long time to germinate. Fescues are mixed in because they tolerate shade and drought very well, but they too take a long time to germinate. Lastly, there is ryegrass. Mixed usually have a combination of annual and perennial ryegrass because they do germinate quickly – usually about 5-7 days. Therefore, assuming you have at least a few hours of direct sun daily, I would experiment with a combination of annual and perennial ryegrass. Follow the sowing instructions, making sure that the seed and soil is kept moist constantly during the germination process. If you are trying this in containers consider covering them with plastic wrap (therefore creating mini greenhouses) for the first week to increase humidity and chance of success. From there, you will then need to practice proper turf maintenance. When you water, you should use a fair amount and water “deeply” so that the roots are encouraged to grow long and deep into the soil. Strong root development has a direct correlation to the vigor and success of your grass above ground, simply called the “root-to-shoot” ratio. Once the grass gets to 2” tall you can begin to cut it regularly. Let the cuttings fall back into the containers because the recycling of nutrients is important. Do not keep it cut too short because you do not want to stress the plant unnecessarily.

As I have said, I have never tried this myself, but I do think it is certainly worth a shot. If your area is more shaded then you may consider trying fescue seed, but again, that does take a lot longer to germinate. Let me know how the experiment works for you. I will be very curious to hear.

How to Care for a Macodes petola in New Jersey

Question:
I was recently given a Macodes petola and I do not know how to care for it. Can you please tell me this plant's proper light, fertilizer, and water requirements?

Answer:
Macodes petola, or jewel orchid, is a very unique member of the orchid family. I first saw one of these when I was a student at the NYBG and I could not believe my eyes. This orchid has dark green leaves with yellow venation that is truly a sight to behold. The yellow venation is so sparkly and bright you might think the plant looks like it is made of gold or is somehow illuminated! This is one such orchid that I would love to have in my collection not so much for the flower as much as the foliage.

As far as caring for your Macodes petola, they are particular but not impossible to keep alive. The first particular is that this orchid requires very high humidity. A bathroom with good airflow and indirect sun would be an appropriate setting. If that is not an option, place it near an open window where it can get some of the natural humidity from outside. If you are not doing so already, place some stones in your saucer to create a buffer so that excess water that collects in the saucer can evaporate and provide humidity without running the risk of rotting the roots. Do not allow the sphagnum moss that the orchid is planted in to dry out completely; it needs to be kept moist at all times. Regarding light requirements, be sure that your Macodes is never kept in a spot where it will get direct sunlight. Indirect sunlight is fine, but direct sun will burn the foliage in no time. The leaves look delicate and in fact they are much more sensitive than other more sturdy orchids (phalaenopsis, oncidiums, cattleyas,etc.) we typically see for sale. If you wish you can fertilize "weakly weekly" as you would your other orchids this time of year.

Name This Plant?

Every week I receive a number of emails of plant images that people need help identifying. Typically I can narrow the plant down to genus at least. Some times, however, it is not that easy. This is one such example. This plant was bought at a garden center in New Jersey about five years ago, and the owner has been trying to identify it ever since. According to the owner, "it is now in a room with western light and seems happier. It also likes to be misted once a week in the winter and 2 times a week in summer. When purchased, it had deep orange flowers w/black pistils or stamens. I have since had 1 or 2 flowers during the entire time I've had this 'plant'......fertilizing (w/plant food) does not seem to do a great deal except perhaps encourage a bit of leaf growth."

Being that this plant has been acting so oddly, I doubt that it is a traditional house plant. As the owner thinks, and as the stems might describe, perhaps it is a woody shrub from a warmer zone that she has been able to keep alive inside her home. As I continue to unravel this mystery, I thought I would post the pictures to see if any of you had any ideas as to what our mystery plant might be. So, my question to you, can you name this plant? Email me your thoughts; I would be thrilled to hear them!