Gardening Granny's Gardening Pages: August 21, 2018 Kim’s Weekly Garden Blog

Hi Gardeners

Dahlias

It’s raining as I write today, a beautiful soaking rain. All the plants are perky looking. I’ve got a jam-packed blog here for you today, courtesy of the rain.

The end of the garden bloom cycle is nearing. The hardy hibiscus is in bloom and the toad lilies and anemones are about to bloom. Goldenrod and heath asters are blooming. My annuals are for the most part, still putting on a good show. Zinnias, cosmos, marigolds, tithonia, garden phlox, dahlias, 4 o clocks, morning glories, salvia and nicotiana are just some of the things blooming away.

The crocosemia, tuberose, and peacock orchids still haven’t bloomed, but I’m excited because my Hawaiian hibiscus now has buds. I got it as a tiny twig and now it’s 6 feet tall. It will have white dangling flowers. However, another “hibiscus” I got this spring, Abelmoschus moschatus, also called musk mallow, has not bloomed nor can I see buds yet and it’s nearly as tall. It’s supposed to have seeds that were once used in perfume making, with a flowery musk scent. It’s an annual plant so it better hurry up.

We got a few small ears of sweet corn from the garden this week, but that harvest is essentially over. I am going to cut down the whole patch because smut is developing, and the remaining ears are underdeveloped from poor pollination. Some people actually eat corn smut like they do mushrooms, but I am not one of them.

I have been sorting through catalogs looking at fall planted bulbs and trying to make a decision. I made an earlier order for lily bulbs and a new peony but now it’s time to decide on bulbs for my enlarged front garden. I love tulips but so do deer and the last 2 years they ate more of them than I expected them to. They don’t eat daffodils and narcissus and I really should concentrate on those for spring color. Plus, daffodils are more likely to return and multiply each year. But my eyes keep going back to those lovely tulips.

I like Colorblends- a large quantity bulb catalog that caters to professional gardeners. They have so many lovely pre-blended mixes of tulips and other bulbs. Their bulbs are huge and healthy and the quantity prices very reasonable. I always say I’ll just make the minimum purchase but always go over that. (catalog links page below.) http://gardeninggrannysgardenpages.blogspot.com/p/have-youreceived-any-garden-catalogs-in.html

There’s an advantage of sampling small amounts of various bulb cultivars from regular catalogs, you get to see a wide selection of blooms, but they cost more per bulb this way. Bulbs do look better planted in drifts or clusters and 100 daffodils is much more spectacular than 10. But then when you buy quantities of 100 you have to plant 100, and I always buy more than one type so that’s a lot of planting. Decisions, decisions.

Did you try to ID the plant I posted in the plant ID article last week?

The answer was its Allegany vine, Adlumia fungosa. Here’s a link to more information on the plant; https://gardeninggrannysgardenpages.blogspot.com/p/alleganyvine-climbing-bleeding-hearts.html

Helping Tired annuals

Annuals in containers and baskets may not be looking their best at this time of the year. Depending on where you live they may have 4-8 weeks or more of bloom time before a hard frost kills them. Annuals may need some trimming and deadheading (removing dead flowers), to keep them looking nice, especially those in containers. If they are looking really straggly shear them back a bit – 1/3 to 2/3 of the stem length depending on what the plant looks like. Give them some liquid fertilizer, keep them watered and hope for a quick reboot.

Don’t forget to keep containers and baskets watered as we get into cooler weather- unless we have a lot of fall rain. Sometimes plants in poorly draining containers can get waterlogged and the roots will rot as the weather gets cooler. Water doesn’t evaporate moisture out of the pots as quickly as before. But sometimes when it seems rainy and cool, pots and containers may actually be dry. There may not have been enough rain to penetrate the foliage or it was shed over the side of the pot by mature leaves. Feel the soil in containers and baskets before watering.

Annuals in the ground should be at their best right about now, if you have been faithful watering them, and are probably carrying the color in the late summer garden. It’s fine to give them a fertilizer boost now. You can also fertilize tropical blooming container plants like hibiscus or mandevilla that you plan on bringing inside for the winter or leaving to die with frost.

However, don’t fertilize perennials in the garden, even late blooming ones, as this often causes new growth which won’t harden off properly for winter. Don’t fertilize foliage houseplants summering outside now either.

If things are looking really bad because of drought, neglect or disease it may be time to simply rip them out and take them to the compost pile. If you still want color you can pop in some potted mums. Some garden stores may have other things in bloom, like pansies or calendula that like cooler weather that you can plant.

If you plant those potted mums in the ground early, and keep them watered if it’s dry, you have a decent chance of them returning next year. Do not cut back any dead foliage in late fall, wait until spring. If you see new growth in the spring you can carefully trim off the old foliage then.

Should you use landscape fabric?

When commercial landscapers install a landscape they often use landscape fabric under mulch. Home gardeners are also using it- but is it a good idea in either case? There are uses for landscape fabric in the home landscape but in many places it’s not a good idea to use this fabric.

Landscape fabric is usually some form of perforated plastic or woven fabric that is sold in rolls. The theory is that the perforations or gaps in the weave will allow water and air to pass through but prevent weeds from growing. The fabric keeps various mulches from settling into the soil and disappearing. (In this article we are not talking about the rolls of plastic mulch used for vegetable and fruit production.)

While it sounds like it would be very helpful, landscape fabric is often neither helpful or appropriate. Anyone who has ever tried to garden in an area where old landscape fabric exists will tell you about the cursing that ensues when trying to move plants, plant things or even weed. After a few years the plants have grown and the tiny holes in the fabric where they were once planted no longer allow the plants removal without cutting, digging and cursing. Weeds have grown on top of the fabric- easy to pull- and into the fabric- terrible to pull. The soil is impossible to amend, and time has clogged those little holes in the fabric that once allowed water and air exchange.

If you go through the intensive effort to remove old landscape fabric to make changes to the landscape, you’ll find that the soil under the fabric is compacted. Air, water and nutrients have been excluded or limited for a while and the soil is not very healthy. And if you look on top of the bed you’ll see that weeds are still able to grow.

Landscape fabric is appropriate under a path or drive that is intended to be long term. It can be put under stone mulches or patio stones to keep them from working down into the soil, if nothing is being planted there. It can be put under porches or low decks to help suppress weeds. While some weeds will still grow they will be easy to pull if they are promptly removed. Landscape fabric is not a good idea under patio stones if you want moss or other tiny plants to grow between them.

Landscape fabric does not work well under organic mulches such as wood chips. These will break down and form a layer of compost on top of the fabric in which weeds will grow quite well. Some of weeds will put roots into the fabric and will be difficult to pull.

Landscape fabric is never appropriate in beds where plants will be installed. Your weeding will not be substantially decreased, and the fabric doesn’t allow the soil surface to “breathe” well. The soil microbiota needed for healthy soil will decline under the fabric. After a time, water doesn’t flow well through the fabric, which deprives plants of moisture.

Mulch is generally used to cover the fabric because it’s not very appealing looking on its own. Mulch generally breaks down and the organic matter enriches the soil, if there is no fabric beneath it. As more mulch is added year after year a layer of compost develops on top that supports weed growth quite well. The soil compacts beneath the fabric, which makes it harder for the roots of the plants planted through it to survive.

Placing stone mulch over landscape fabric and then planting through it is not recommended either. You’ll have the same problems, if not more, with soil health being affected, the soil being compacted, and even weeds growing into it.

Most gardeners like to move plants around and plant more things into the garden. Dead and diseased plants need to be taken out. This is difficult when there’s a layer of landscape fabric under everything.

Then there’s the critter problem. Landscape fabric makes a nice place for mice, voles and other things to create homes beneath. They have no problem chewing access holes. Snakes go under the fabric looking for the mice and voles, or to make their own home. Insects and slugs also appreciate landscape fabric homes.

A good gardener should not place landscape fabric under planting areas. It has its place under areas that you don’t intend to plant in for a long time but other uses cause soil problems and make gardening harder, not easier.

Growing cucumbers

Cucumbers are a great crop for a small garden because one plant yields a lot and because they can be trained to grow up a trellis so they take up vertical, not horizontal space. You can use them fresh or turn them into pickles for storage. There are some bush type cucumbers that can also be grown in a pot.

Common, (monoecious), cucumbers have both male and female flowers on the same plant. They are the most productive types for growing outside in the home garden where you want a long season of harvest. There are two main types of these cucumbers. One has white spines and is the variety best for fresh use. They are usually long and narrow. The other type has black spines and is usually shorter and fatter. This is the best type for pickles. But either type can be used either way. Catalogs will often label them as slicers or pickling cukes.

There are some odd cucumber varieties such as brown, white or reddish ones and some that form a round fruit. Gherkins are not really a cucumber but a related species. Baby cukes are just cucumbers harvested when small.

Parthenocarpic type cucumber

There are special varieties of cukes that are better for greenhouse production. Many of these are parthenocarpic, that is they produce fruit without being pollinated. They are seedless or nearly seedless but must be isolated from other types of cukes. They generally have long narrow fruits with thin skin and are used as slicing or fresh cukes. The seed or the plants are more expensive than other cucumbers.

Gynoecious cucumbers are varieties that have been developed that have all or mostly female flowers. They usually produce most of their fruit at one time, which may be good if you want to make pickles. But they need to have a regular cucumber or two which have male flowers planted among them to get fruit.

Cucumbers are a vine crop. Vines can get 10 feet long in some cases and have white bumps along the stems. The leaves are triangular. The whole plant has a prickly, sticky feel. The flowers are yellow and are either male or female in the normal monoecious garden cucumber. Male flowers don’t produce fruit. Female flowers have a small cuke attached at the back. Male flowers without the baby attached usually begin to bloom first, but in suitable weather female flowers will shortly follow. Cucumbers are insect pollinated but you only need one plant to get cucumbers.

Cucumber fruits can be bumpy or smooth on the outside depending on variety. They are usually dark green, with paler striping on some when immature. They turn yellow, white or brown when ripe.

Cucumbers are a warm weather crop and should be planted after all danger of frost has passed in your area. They grow quickly from seed and can be planted directly in the ground where they are to grow. Some gardeners will start seeds inside earlier or buy transplants to set out. Small transplants are better than larger ones at quickly establishing themselves.

Plant cucumbers in full sun. For best fruit production they require even, consistent amounts of water, as a cucumber fruit is primarily water. You can fertilize with a garden fertilizer at planting, but it may not be necessary in good soil. Many people plant cucumbers in a mound of soil with 3-4 plants in a 2 feet diameter mound but planting them in rows is fine too. Space plants about 12 inches apart.

If you are going to use some kind of trellis for the cucumbers to climb put that in place when you plant them. A piece of wire fence between two poles is a good trellis. The trellis can be at an angle or straight up and down. You may have to help the young plants vining stems find a trellis in the beginning but after that they should not need to be tied up.

Cucumbers can also be allowed to sprawl on the ground. This works best with mulch underneath the plants to keep the fruit clean. Each plant will take up a good bit of room this way, at least 6 feet.

Harvest cucumbers when they are young and small for the best fresh, slicing cucumbers. Pickling cucumbers can be allowed to get a little bigger. A little yellow on the bottom is ok. Most cucumber fruits turn yellow when they are ripe, a few turn white. You don’t want them to get to this stage. They will have large seeds and the flavor is poor. But do pick any yellow cucumbers you see and feed them to the chickens or put them in the compost pile. If you leave them to finish ripening, it’s a signal to the plant to stop producing fruits.

The most common problem of cucumbers is powdery mildew. In this fungal disease the leaves get grayish, fuzzy spots that turn into a coating. Leaves then dry up and fall off. It’s most prevalent in warm, humid weather but can pop up at other times. Plants stressed by lack of water but in humid conditions are often affected. Shaded leaves and older leaves show symptoms first. The plants may put out new leaves at the end of the vine and continue to set a few fruits, but they won’t produce well.

Downy mildew is a worse problem because vines will rapidly die. It is more of a problem when the weather turns cool, wet and cloudy and later in the season. The leaves will get yellow angular spots on the top between leaf veins and fuzzy grayish brown to black spots on the underside, then the whole plant quickly dies. This fungal disease will also spread to squash, melons and pumpkins.

Fungal diseases can’t be cured, only prevented. They are often blown in on the wind. To prevent powdery and downy mildew plant resistant varieties and use a garden fungicide through the season as the label directs. Don’t water in the evening and don’t crowd plants. Home remedies of baking soda and milk are not effective at prevention and certainly not as a cure. Epsom salt does absolutely nothing and may harm plants further.

Cucumber beetles are a pest of cucumbers. There are striped and spotted varieties. They are long beetles, usually yellow with black spots or stripes. The spotted cucumber beetle will feed on all kinds of plants, but the striped cucumber beetle usually sticks to cucumbers, melons and squash.

Spotted cucumber beetles lay their eggs on the roots of grasses and corn and the larvae feed there. Only the adults eat the cucumber plant. Striped cucumber beetles lay eggs at the base of cucumber plants and both adults and larvae feed on them. Feeding by beetles stunts growth, they may eat flowers and reduce yield and the beetles can carry bacterial diseases.

Cucumber beetle control can be helped by mulching plants with straw, which encourages predator insects, or using reflective plastic mulch which repels them. Using a hand vac to suck up beetles can help. Don’t plant cucumbers in the same spot each year because the beetles can overwinter. Gardeners can also use garden insecticides according to label directions.

Cucumbers are rarely bothered by animal pests, unless you count chickens left to roam the garden.

Chinese foxglove- Rehmannia angulate or Rehmannia elata

I remember this lovely plant from my grandmother’s garden and I remember she was proud of it for some reason, maybe because it wasn’t common or hardy in her growing zone. It turns out it used to be grown more frequently in gardens until about the 1960’s and it’s a shame gardeners aren’t growing it more often now. It has been grown in American gardens since at least 1830. I was able to get a small plant from Select Seed this spring and I am very happy with the plant, which now, after a couple months, is large and producing lots of flowers.

Chinese foxglove

There are two scientific names floating around for the plant, Rehmannia elata is probably the most common. It’s called Chinese Foxglove (common name) because its native to China and the flowers somewhat resemble the common foxglove. It’s related to Rehmanniae radix, an important herb in Chinese medicine.

Chinese foxglove is not related to the common garden foxglove many gardeners are familiar with. It has larger flowers and blooms much longer than regular foxglove. The foliage stays green through summer and turns red in the fall in colder areas. In zones 8 and above it’s evergreen and may bloom through the winter season.

This pretty plant has a basal rosette of foliage at first, then sends up blooming stalks with alternate leaves. The leaves are rough textured with fine hairs and prominent veins. They have an irregularly scalloped edge and grow up to 10 inches long. Plants average 2-3 feet high with bloom stalks but can get to 5 feet high in perfect conditions. Plants have rhizomes as roots and spread quickly in good conditions. My small plant has numerous daughter plants in it’s first year of growth.

The flowers of Chinese foxglove are tubular, with a flared lip of 3 fused petals and dangle downward. They are about 3 inches long. Most are a rosy, peachy pink with a yellow throat dotted with carmine. Some nurseries have developed strains with deeper pink flowers and there is a rare white variety that’s hard to find. It must be started by cuttings. The plants are free blooming, with stalks of flowers from spring to frost. Bees and hummingbirds are attracted to the flowers.

Chinese foxglove likes rich, moist, well-drained soil but is tolerant of most soil types. In the north it will grow in full sun if kept well-watered. My plants receive nearly full sun. Above zone 7 it should in partial or dappled shade. It’s biggest drawback, that I can see, is that it’s not hardy in zone 6 and lower and in zone 7 must be heavily mulched. I intend to save seed and also to try and overwinter a young plant on the unheated porch.

Rehmania elata is fairly easy to start from seed and will bloom the first year. It should be started inside 8-10 weeks before your last frost. The seeds need warm soil to germinate and should be lightly pressed into the soil because light is also needed for germination. It’s important to keep the seeds evenly moist until germination. Gardeners can find small plants from specialty nurseries on line but it’s uncommon to see them in many retail greenhouses in the northern states.

In zones 7 and higher where the plant is hardy it can spread quickly and make large clumps and some southern gardeners consider it invasive. The plants can be divided and started from cuttings also.

Look at all the small plants coming up at the base

In the US this plant has few insect or disease problems. Slugs are said to eat it, although they don’t normally prefer plants with rough leaves like it has so I am skeptical. I have seen Japanese beetles on the plants but have noticed little damage.

While Chinese foxglove is related to a commercially important herbal plant, little is known about this species herbal value. It has toxic properties though and should not be experimented with. I would consider it poisonous.

Downy Mildew in Impatiens Update

Almost every gardener has grown impatiens ( Impatiens walleriana) in a shady or semi-shady spot in the garden. Impatiens is known for long lasting color in the garden or in containers and until recently had few insect and disease problems. A few years ago however, a new disease for impatiens, downy mildew, was causing great concern for growers and gardeners alike. For a while it was thought that gardeners would no longer to able to grow impatiens successfully in the garden and they nearly disappeared from retail stores. But things have changed, and impatiens are back in garden stores.

But just because impatiens are for sale again doesn’t mean the problem has totally went away. The key to success is having growers treat impatiens in the greenhouse with certain fungicides. If done correctly they will protect the plants after they leave the greenhouse until the growing season nears its end. Plants that are resistant to downy mildew have also been developed.

But gardeners who start their own seeds and small greenhouses which want to remain organic or who don’t treat plants because of other reasons may still produce plants susceptible to the disease. The disease can pop up at any time of the season in plants that haven’t been protected by fungicide treatments in the greenhouse. So, gardeners should be aware of the disease and what to look for.

Impatiens downy mildew, Plasmopara obducens, is a fungal disease that prefers cool, moist conditions. Heavy dews and high humidity favor its spread. It can spread by windborne fungal spores or by contact. Gardeners can carry the fungal spores on their hands, clothes and tools. You can bring it home from the nursery or it can turn up in your garden later, blown in on the wind. Once it starts downy mildew kills your impatiens plants in a few weeks. Once a plant gets downy mildew it can’t be cured.

Many other garden plants have problems with downy mildew, but each species of plant has their own forms of downy mildew and usually the downy mildew on one type of plant will not infect other types of plants. Impatiens downy mildew will infect garden balsam, a close relative, and some wild impatiens species, but not cucumbers or roses for example. New Guinea impatiens and some new hybrid species of impatiens are very resistant to impatiens downy mildew.

Symptoms of downy mildew in impatiens

Gardeners should examine their impatiens plantings every few days, especially when the weather is cool and damp. It often occurs late in the growing season and even treated plants may succumb to the disease if the season is long. Here are the symptoms of impatiens downy mildew.

Stippled (little spots) upper surfaces of leaves

Yellowing leaves

Curling leaf edges

Wilted look

Dropping leaves and flowers,

Bare stems

Stunted look

White, fuzzy coating on the underside of leaves

The white fuzzy coating is fungal spores and they are not always present, especially if the weather has turned warm and dry. But when the plants do have spores it is a good diagnostic sign. You can rub off this coating with your fingers.

What to do when you find impatiens downy mildew

When the symptoms of downy mildew show up the plants infected, and those on either side, even if they look fine, should be pulled up. Plants cannot be successfully treated once the disease starts. Try to get all roots and don’t leave any leaves or stems behind that break off. Put the plants in plastic bags and tie them for safe disposal. Do not put them in the compost pile or leave them lying on the ground. Keep a close watch on the rest of the plants. You can plant an alternative species such as coleus in the spot where you pulled out the impatiens but don’t re-plant impatiens plants.

One unfortunate thing about downy mildew is that it also produces a special type of spore that over winters in plant stems and roots and then it will re-infect new plants planted in the spring. Once it settles in the soil and garden debris it can be in the garden for a long time. At the close of the season gardeners should remove all impatiens plants, including the roots, even if they did not seem infected. Put these plants and parts in plastic bags to dispose of them and do not compost them.

Other things to help prevent impatiens downy mildew are listed below.

Inspect plants carefully before buying them. Don’t buy plants that have any of the symptoms above.

Wait until the weather is warm and settled before planting impatiens.

Don’t water or irrigate in the evening, make sure plants dry off before nightfall.

Try to avoid overhead watering if you can, use trickle irrigation at the roots or water containers so that you don’t wet the foliage.

You may want to avoid mulch around impatiens as it can keep the soil surface moist and favorable for fungal spore survival.

Make sure to remove all impatiens plant parts, including roots, when frost has killed the plants, or you are ready to clean up the garden for winter.

If you had downy mildew this year you will want to avoid planting impatiens in that spot next year. Chose other plants such as coleus, begonias, or vinca for planting in the spot. If the infected plants were in a container remove all the soil and dispose of it. Then wash the container inside and out with hot soapy water and re-fill it with clean potting mix.

Home gardeners who think their plants aren’t treated or are starting their own seeds might try protecting the plants using any garden fungicide registered for other flowers, although some products may not protect impatiens from downy mildew. The protection needs to start in the greenhouse or when home gardeners start seeds indoors or as soon as you bring transplants home. Downy mildew and powdery mildew are two separate diseases and products that work for powdery mildew may not work for downy mildew.

If you love impatiens and like to use them for color in the shade, consider buying your plants from a greenhouse that treats the plants with protective fungicides. Most large wholesale growers that furnish plants to the big retail stores will probably be using fungicides. Most knowledgeable local greenhouses will also treat plants, since problems with the disease can begin in the greenhouse and cost them money.

Gardeners should realize that treated plants may still develop the disease at the end of the season, and if they do the procedures listed earlier in the article should be followed. It still may be a good idea for gardeners to use impatiens in small quantities and rotate flowering species as bedding plants from year to year.

There’s no information on whether the fungicides affect pollinators after the plants leave the greenhouse, but impatiens aren’t heavily visited by pollinators in the garden anyway. Fungicides are generally not as harmful to insects as other pesticides, but experts are still trying to determine what effect the various fungicides have on pollinators. One thing is sure though, homemade concoctions like baking soda, milk, – or worse Epsom salts, will not prevent or cure downy mildew and may be harmful to pollinators also.

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Tuesday, August 21, 2018

August 21, 2018 Kim’s Weekly Garden Blog

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