Articles

Reading Lisa Tome’s recent column made me chuckle. The column dad and I take turns writing is supposed to be about gardening. Inspiration generally comes from our own yards, bird watching trips, and more often than not, customers’ questions. Sometimes the idea fountain dries up, that’s when you get a history lesson like last week’s marigold article, which came from a class I taught at Longwood. Luckily this week I have a question to answer.

“There is a white coating on my bee balm that happens every year and sometimes kills the plant. What am I doing wrong?”

It’s not you- it’s powdery mildew. It is a fungal disease that is common on certain plants most notably, summer phlox, lilacs, bee balm, veronica, golden rod, dahlias, grapes, squash and cucumbers and some others. If you find white of light gray powdery patches on the upper surface of leaves odds are it’s powdery mildew. Infections rates are highest in the summer, when humidity levels rise and temperatures warm.

Lower leaves are affected first, and often defoliate. The infection spreads up the plant in extreme cases. Sometimes even killing the plant.

Powdery mildew is a group of fungi- the ones that affect lilacs are different than the ones that affect grapes, or phlox. No need to worry that one will infect neighboring plants of a different species.

So what can you do?Good air circulation is key- space plants that are affected apart from each other. Rather than a large phlox bed, separate them with other types of perennials. Also give plants some room for breeze to dry the foliage. Relative humidity of 90% is not good for people, but great for powdery mildew spore germination. Prune or divide large or overgrown plantings to improve air flow.

Choose resistant cultivars. If you must have summer phlox and have been plagued with powdery mildew, try ‘Jeanna’ or ‘David’. Both of those have some level of resistance. If you love bee balm, try ‘Jacob Kline’. Lilacs lovers try ‘Miss Kim’.

Avoid keeping foliage wet in the evening. Conventional wisdom says water in the evening when less water is lost due to evaporation. That’s ok as long as the foliage dries before nightfall. Try soaker hoses instead of overhead sprinklers for affected plants. The fungal spores aren’t splashed by rain or irrigation as much as the high humidity causes the problem.

There is an old folk remedy that has been scientifically proven effective. My grandmother always used to rinse out her milk jugs and dump it on her phlox and bee balm. Turns out a 1:10 dilution of milk water is a god preventative and actually slows fungal growth.

Chemical treatments in extreme cases include sulfur, neem oil and potassium bicarbonate. Commercial formulations are available at hardware stores, or garden centers.

Most important is removing infected foliage. Do not compost diseased tissue, as temperatures inside compost piles are not high enough to kill spores. Bag diseased foliage at the end of the season and dump it or burn it.

Hopefully inspiration will strike next week, or I’ll be lucky enough for someone to ask me a question.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

No one really thinks about the lowly marigold. They appear in market packs in the local greenhouses in the spring. They ring vegetable gardens and annual borders in the summer. Kindergarteners plant them in milk cartons. They die in the frost.

But the story behind how the modern marigold came to be is quite fascinating.

Both African and French marigolds are actually native to Mexico and Central America. Monks traveling with Spanish explorers in the 1500-1600s gathered seeds and took them back to Europe, stopping at monastaries in North Africa and France on their way to Spain. There they were called “Mary’s Gold” symbolizing the golden flower often painted in religious icons at the time. Hapless English explores to France and Spain, thinking they discovered something new, renamed them French and African marigolds.

Colonialists  brought marigolds to the US in the late 1700s.  They were all but passé by the mid 1800s.

Until they met their champion in David Burpee. When he took over the family seed business from his father in the early 1900’s he single-mindedly became a cheerleader for the pedestrian marigold.

First of all, he hired breeders at Burpee to improve the habit and flower appearance. From there he had a three-pronged approach to reach out to gardeners and homeowners. He started Marigold Appreciation Societies around the country for the cultivation of marigolds. He sponsored a contest with a $10,000 cash prize for the first white-flowered marigold. Mrs. Alice Vonk, of Sully, Iowa took the prize in 1975. He even teamed up with a local California senator to try to have marigolds named the national flower. (He lost the bid to the rose). This man in his tireless efforts did more to improve and re-popularize this garden staple than anyone else. By the 1980's marigolds were in the top 5 best selling annuals.

Did you know, marigold flowers are edible? They have high levels of xanthophylls (related to beta caroltene) in their petals. When poultry farmers started raising chickens intensively and no longer allowing them to free range , their diet suffered. Marigold petals were fed to chickens to improve the color of the skin and egg yolks. Now instead of actual flowers- marigold extract if often added to chicken food.

Telling them apart is easy- African marigold are taller with fully -double crested flower heads in yellow, orange and cream. They used to get pretty beat up in heavy rain or wind, but have been bred to have more sturdy stems. French marigolds are more petitie with single, semi-double or double smaller flowers. They come in yellow, orange, red, and gold- often bicolors as well.

Gardeners plant them around vegetable gardens to deter rabbits, which they probably don’t do well. But they are beneficial in that they repel harmful nematodes that attack the roots of potatoes, tomatoes and peppers. So keep planting them with your vegetables.

The lowly marigold- maybe not so boring if you know the whole story.

June has more than made up for the rain deficit of April and May. All the water the last few weeks has leached most nutrients from hanging baskets and patio planters If you bought beautiful hanging baskets around Mother’s Day, they may be looking yellow and ratty. You are not alone. Here are some pointers to keeping hanging baskets nice all summer long.

Problem- yellow foliage

Most greenhouses fertilize at a low rate every watering with a balanced water-soluble fertilizer. If you have not been fertilizing at all, this is a good place to start. A shot of blue water will help green them up. Addition of time release fertilizer like Osmocote will release a little bit at a time, but they are temperature dependant. The warmer it is, the faster it releases.

There are some plants that need additional iron. In people, the iron in our blood helps to carry oxygen throughout our bodies. In plants, this mineral plays an important role in photosynthesis. Calibrachoa, petunias, bacopa, diascia and nemesia are particularly iron-hungry. Without supplemental iron, their foliage quickly yellows.

Iron is more readily available for the plants to use at a lower pH. Without getting too technical- if your water is basic, pH above 7, there may be iron there but the plants can’t “see” it. Look for a fertilizer that acidifies, and offers supplemental chelated iron. It can either be sprayed directly on the foliage or watered into the soil. Keep extra iron away from geraniums, pentas, and marigolds.

Problem-no flowers  

Have you been fertilizing too much? This is one of those situations where if one scoop is good two scoops are NOT better. Too much nitrogen causes excessive vegetative growth. This means all stems and leaves and no flowers. Back off on the fertilizer a bit, or try one with a higher phosphorous component.

The three numbers on your fertilizer bag stand for nitrogen (N), phosphorus (P) and potassium (K). A famous brand that comes in a green-and-yellow box has a good bloom-boosting product that contains a higher amount of phosphorus. There are also organic products available if you'd rather go that route, derived from bonemeal, fish emulsions, potash, and the like. They should also have the chemical analysis listed on the label.

Problem-only flowers at the bottom

This solution is easy. Give it a haircut. Some annuals only seem to flower on growing tips. If you cut the plants back, it encourages the side branches to grow out and flower. You will be rewarded with bushier, more floriferous baskets that at least in the shot-run won’t require as much water.

Problem- Cool season annuals died

Some plants that take cool spring temperatures melt out in the heat. If your lobelia or pansy baskets are looking anemic- swap out heat lovers like lantana, blue evolovulus, or petunias to carry you through the rest of the summer.

The only other tips I can offer are to watch where you put your baskets to keep plant light requirements in line. Petunias are not going to be happy on a deeply shaded porch. By the same token torenia, begonias, and fuchsias don’t want to bake in afternoon sun.

Beautiful hanging baskets are not that hard, and with these tips, you can make your entryway or porch beautiful all summer long.

Some weeks ago I muttered about the severe winter and was on the verge of writing obituaries for a number of plants. By luck, age, schedule or laziness I successfully avoided violating a gardening principle I have often repeated here. Give plants plenty of time to recover in the spring.

The hydrangeas provided the biggest surprise.Although most of the lace caps and mopheads suffered dieback to near the ground they have rebounded impressively. Most are at least twice as large as last year, their first, and blooming well. I counted about 18 flowers on the best one and it is just under two feet tall.

I’ll stick to my claim that we are on the northern edge for most colorful hydrangeas, but I think the age of re-blooming hydrangeas is upon us. About colors I’ll just say, wow.There are other types of hydrangeas that generally flower white and are much tougher.

Large leaf rhododendrons started with lots of brown leaves but quickly put out new growth. Unfortunately, no flowers this year. The small leaf ones lost most of their leaves, but bloomed well. They too, quickly grew out. The deciduous ones preformed perfectly.

The Japanese holly, Sky Pencil, looked hopeless, but has sprouted out reasonably well. It is about two thirds as tall as it was and a bit sparse but promising enough to remain for another season. I have too much shade for crape myrtles but the ones at the farm need some creative pruning.

Last week I admitted to be pondering about winter interest in my shady gardens. To date I have not planted the best shade conifer, yews. They get a bad rap for being over planted but one must praise their willingness to grow anywhere that is not too wet.

Shade is tougher to define than sun. With morning sun plant just about anything. With afternoon sun look at the tougher ones to survive the heat and often wind and dryness.

A few days ago I watched two spots less than ten feet apart where I had built trellis. One was in and out of sun while the other waited. When I built them, with no leaves on the trees, I believed that both would have reasonable sun.

Back to evergreens. I believe that yellow foliage will outperform green in moderate to light shade. I also am cautiously optimistic about some arborvitae.

The problem with shade is that it causes plants to stretch. A thin evergreen with widely spaced limbs is usually not the goal.Grasses that will tolerate shade are often short. For reasonable size any of the many carex will tolerate shade but prefer more moisture than shady hillsides like mine generally offer. One of the calamagrostis also is a possibility. 'Karl Foerster' is the most common one. I am tempted to plant some of the large headed ones in my best sun but fear the shade will cause them to flop.

Gardening success comes when you know your site and pick plants to match it. But sometimes the fun is experimenting, I almost said gambling, and hope for winners.

After nearly 30 years the frog has arisen from his long hibernation and now sits guarding and spitting water into a small pond near my new patio.

I fell in love with the frog on a visit to a pottery wholesaler. I had this ill-advised idea to sell some decorative pots to supplement our income from the orchard and few greenhouses in the mid eighties. The intention with the frog was what is stated above but sometimes it takes me a while to get things done.The frog is simply an indicator that progress on my five year plan to have a nice yard is moving along well. It is hard to believe that this is already our third summer near Wakefield. Gone is the mower sliding board bank in the front yard and the backyard hole where the stumps were buried. The area mowed had been reduced in half. At least 80% of the mowed area is now real grass instead of a motley collection of weeds, crab grass, bare ground and something that pretended to be grass in good weather.

I sought professional help selecting the appropriate grass seed. Otherwise I killed what little was there, spread about 20 yards of mushroom soil, tilled and leveled, seeded and covered with straw myself. Some was planted last August, the rest early this spring.The result is not perfect but pretty darn good. I will most likely start to attack the remaining mowed areas in the next few weeks and repeat the above process. Last year I tried a small vegetable garden but concluded that I had too much shade so that area was seeded with grass this spring.

When I moved in, the back of the house featured two small decks on two levels. The upper level was fenced for want of a better term and the bottom was not. On the lower level you could not have much fun without fear of tumbling one step into the yard. The lower level was removed and replaced by a 20 by 30 foot patio.

First, four to six inches of stone dust went in. Several months, several rains, frequent waterings and rakings followed. When convinced it was solid I began to lay cobles. When informed, my four year old grandson wanted to help. His block laying needed scrutiny but he soon decided just to hand me the blocks. That worked well.His jealous school-age sisters were disappointed so they came with my son the next Saturday. It was amazing what two men could do when three little kids handed you blocks. I laid the last few Christmas morning just before winter  

What’s left? The three large flower beds that replaced the mower zone are progressing nicely but still lack the

winter interest that I want.Tall ornamental grasses and most conifers want more sun than I have. Wind is also a limiting factor. I also need more blooming perennials that will tolerate the shade.We’ll figure that out, but for now the frog is happy that he now has a purpose and I’m happy because progress is ahead of schedule.