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  • July garden tips & tasks

    Make sure the trees and shrubs you planted in spring get plenty of water. The Nashville Tree Foundation advises that trees planted in the last three years should receive 10 gallons per week per inch of tree caliper. Water your trees slowly with a bucket, soaker hose, slow drip hose or watering bag.

    As tomato plants continue to grow and produce, keep the soil around the plants consistently moist. Inconsistent watering is the reason tomatoes develop cracks.

    Summer annuals and perennials such as daisies, glads, zinnias, sunflowers, cosmos and others make beautiful summer bouquets. Cut them early in the day when they’re at their freshest and put them in water in a vase right away. Change the water daily to keep them fresh longer.

    Pick summer squash and zucchini while they are still small and tender for best flavor.

    Watch for tobacco hornworms on tomato plants and Japanese beetles on just about everything else. Pluck the worms off the tomato plants and dispose of them. (If you see one with its back covered with white eggs, leave it; it is being parasitized by a tiny wasp.) Knock Japanese beetles off plants into a bucket of soapy water.

    Cut back the stems of mums once more, before they begin to form flowers. This allows them to delay flowering until fall.

    Lawn growth (and lawn mowing) may slow down as the heat increases. Continue to mow as needed, but don’t cut the grass too short. Provide about an inch of water if it doesn’t rain.

    Don’t forget about those hanging baskets and container gardens in the heat. If it doesn’t rain, you may need to water them daily during the hottest part of summer.

    Overgrown beds of bearded irises should be divided every three to five years. July is a good time for this task.

    You can plant a second crop of summer vegetables that grow quickly. Cucumber, bush beans and zucchini can usually produce a crop by fall if seeds are planted early in July.

    Coleus’ beauty is in the foliage, so when it begins to bloom, pinch off the flower spikes to encourage the plant to grow fuller and bushier.

    Take a daily walk around the garden to enjoy the scenery, but also to spot problems with weeds or bugs before they get out of hand.

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Care for peonies after they bloom

Now that the peonies have finished blooming, what’s the best thing to do with them – leave them or cut them back? Ours often get an ugly coating of powdery mildew on the leaves in the summer. Is there a way to prevent this?

After they bloom, peonies spend the rest of the summer gathering strength to bloom next year before they die back to the roots in winter. A good first task for the gardener is to cut off the faded flowers. Garden expert P. Allen Smith suggests removing the seed pods and lightly fertilizing in late spring or early summer. But be sure to leave the foliage. After the blooms are gone, the rich green leaves of peony shrubs remain an attractive feature in the garden – except when it develops a case of powdery mildew. Continue reading

When daffodils don’t bloom

I covered my daffodils in the fall with a heavy layer of pine straw. The leaves have come up but they are not budding or blooming. Is the pine straw too acidic for these plants?

Daffodil copyAfter a long winter, we look forward to the daffodils blooming in spring, and it’s a disappointment when they don’t produce the flowers we expect.

The failure to bloom is not due to pine straw causing acid soil; daffodils – or jonquils, as we sometimes call them — tolerate a range of soil types, as long as it is well-drained and moderately fertile, and some varieties actually prefer slightly acid soil. A lot of garden experts suggest mulching daffodil beds with a light layer of pine straw. Small, early blooming daffodils may not be able to penetrate a thick layer of mulch.

So consider some of the other possible reasons daffodils don’t bloom: Continue reading

Rose of Sharon is an easy summer favorite

I remember a large Rose of Sharon shrub that grew in my grandmother’s yard that had big, pretty flowers every summer. I’d like to have one for my own garden. Can this shrub be started from cuttings?

Lil Kim Proven Winners

Lil’ Kim Rose of Sharon (H. syriacus) from Proven Winners Plants.

The old-fashioned rose of Sharon, or shrub althaea (Hibiscus syriacus), is easy to grow, and often pops up in unexpected places from dropped seeds. It can also be propagated from stem cuttings. Here are general guidelines for taking cuttings of rose of Sharon and other woody ornamentals:

Cut lengths of softwood (soft, succulent new growth) or semi-hardwood (partially mature wood of the current season’s growth) about six inches long from a healthy host plant. Remove the bottom leaves, and dip the cut ends in rooting hormone powder. Stick the cut ends about one-third their length into a rooting medium that drains well, such as perlite or vermiculite. Cover the cuttings with some sort of plastic covering to maintain a humid environment, and place them in indirect light.

Keep the rooting medium moist until roots develop. It will likely take several weeks, but you’ll know the cuttings have grown roots when you tug gently on the cuttings and feel resistance. Transplant them into containers to allow them to grow to a larger size before you plant them in the garden.

Rose of Sharon grows and blooms best in full sun, and thrives in almost any well-drained soil. Once established, it tolerates heat and drought. Flowers bloom on new growth, so if it needs pruning, you can do that task in winter.

Daffodils can be early risers

It’s mid-January, and the daffodils in our yard are already starting to come up. The shoots are about 3 – 5 inches above the ground. Won’t they freeze when the temperature drops?

DaffodilsIt’s not unusual for the shoots of early-blooming daffodils to begin pushing up through the ground, even as early as January – the same time as the crocuses. Cold weather may slow their growth, but it won’t kill them. This time of year, the worst that could happen is that the weather turns warm and stays warm enough long enough that the daffodils bloom. The flowers might then succumb to a snap of extreme cold, but if buds have not begun to show color, they should be fine.

There are several daffodil cultivars that bloom in late winter, and planting those types can extend the blooming season from late winter into mid-spring. Among the early-blooming favorites are cultivars called ‘Sweetness,’ ‘Jetfire,’ ‘Barrett Browning,’ ‘February Gold,’ and others.

When shoots do begin to pop up, daffodil experts say they benefit from a light dose of bulb fertilizer, scattered lightly around each clump or spread over the surface of naturalized areas. Fertilizer can burn new leaves, so if it gets on the foliage, wash it off right away.

Why lilacs don’t bloom

Question: Our lilac bush receives sunlight for about half the day and bloomed in the past, but not much. Now it does not bloom at all, though the foliage is healthy. It is planted in well-drained soil, and other lilacs in the neighborhood are doing well.

Lilac

Lilac (Syringa vulgaris) ‘Albert F. Holden’

Lilacs are deciduous shrubs that produce clusters of flowers in mid-spring. There are several factors that could keep the plant from flowering, but the most common is the lack of sufficient sunlight. Garden experts who favor lilacs insist that they really need full sun – six or more hours of direct sunlight – to bloom.

As gardens grow and change over the years, the nature of the sunlight the garden receives may also change – trees grow taller and wider and filter more of the sunlight that gets to your garden. Could that be a factor in your landscape?

Lilacs also need adequate water in summer – not just a sprinkling around the roots, but the entire ground, says gardener Anne Owen, who has several years’ experience with growing lilacs in Middle Tennessee.

One other thing to consider is whether the plant needs pruning, which could encourage the setting of new buds and flowers next year (lilacs bloom on the previous year’s growth).

And as always, consider testing the soil. If a soil sample from your garden bed test low in phosphorous, the lilac may respond to an application of fertilizer.

In general, here is what lilacs need to grow well and bloom each spring: Full sun, well-drained soil that is lightly alkaline or neutral pH, regular water. Be aware that they are prone to developing powdery mildew. Also note that lilacs bloom best where winters are consistently cold, and they suffer in long, hot summer nights. If you live in the Southern U.S., garden expert Felder Rushing suggests planting lilacs in well-drained soil on the north side of a building, where it might be colder in winter, and hope for cool August nights.

Too hot to bloom!

QUESTION: I have a pot of impatiens that was doing well, but now the flower buds have been dropping off or turning brown before opening. The pot is always in the shade and I keep it well watered and fed. It has nice green leaves, just no flowers. Any idea what could cause this?

If there are no other symptoms – no spotting of the leaves, no rotting of the stems, no powdery coating or other unusual growth – a good guess at the source of the problem would be the long period of extreme heat. Even in the shade it has been extremely hot (remember that day it hit 109 degrees?) and plants in containers may suffer more because the pot can dry out quickly. A plant under stress will shed its flowers first.

By now, with several days of rain and more reasonable temperatures, the impatiens (and many other things) should begin to recover.

This is a good time to mention again, though, an email I received from UT Extension plant disease expert Alan Windham, in which he warned about the development of downy mildew in beds of impatiens. Watch for plants that are losing leaves, that don’t flower, and that have white growth on the undersides of the leaves, he advises. This disease can be extremely damaging, so pull up, bag and dispose of infected plants to keep it from spreading. There’s more about it at UT Extension’s Soil, Pest and Plant Center Facebook page.

…And too hot to plant, too

QUESTION: My daughter has thinned out her iris bed and given some to me.  She has given me the whole plant (bulbs and stems). I know I can not plant them at this time but how do I store them until they can be planted in November or December?  Do I need to cut the stems off now or leave them as is?  Thanks for any information you can provide. 

You’re right, with too much heat and still too little rain, it’s a bad time to plant anything. Irises are pretty hardy so you can wait to plant the rhizomes.

For now, cut the leaves off to about 3 to 6 inches, and remove as much of the soil from the rhizome as you can. Don’t wash them, just brush off the dried soil. Check to make sure there are no rotting places, insects or diseased-looking spots (discard those if there are) and store them in a cool, dry place.

You don’t need to wait until November to plant them. While they’re pretty hardy, they’d still rather be in the ground, so consider planting in September, or after the worst of the summer heat passes.

When you do get ready to plant, here’s a helpful link from the American Iris Society that provides information.

Another reminder about watering: In spite of all the rain lately, we’re still experiencing severe drought conditions in Middle Tennessee. Young trees suffer most. If you planted trees this spring, give them a little extra attention to help them make it through this hot, dry summer. Click here to see the Nashville Tree Foundation’s guidelines and tips to help keep your trees healthy.