Question and Answer for April 2009

Question: I would like to know what the bush or shrub which I know as the nannyberry bush is called in nursery catalogs. GLR – Wisconsin.

Answer: The shrub bearing the common name nanny-berry is Viburnum Lentago. It is also called sheep-berry and is native to Spain.

Question: We have just bought a new home and we have clay soil. Please advise me as to how to prepare this soil so that I can grow flowers. I want a flower bed, and I would like to do the work myself, if possible. J. R., Illinois.

Answer: A clay soil may be an excellent soil high in mineral plant food but it is an extremely fine textured soil. This makes it difficult to work, easily baked, and hard for plants to secure the water and plant food it contains. To improve the structure of such a soil large amounts of partially decayed organic matter need to be added. As the organic matter decays the humus formed makes the clay friable or crumbly. Also it increases the ability of plants to secure soil moisture.

Finally humus modifies the soil color, improves soil bacteria action and increases the quantity of plant food available. If a clay soil is well drained the addition of a heavy application of partially decayed stable dressing is all that is necessary to prepare it for a flower bed. At least a four-inch layer of organic matter should be spread over the clay and then spaded into the bed. This should be repeated in the fall and may well be continued each fall thereafter.

Question: Can you advise me about using sawdust as a mulch? Can it be used year after year? B.Y., Colorado.

Answer: The chief reason for applying a mulch is to conserve moisture in the soil. Sawdust will serve this purpose and if it is not applied in too heavy amounts could be used year after year. It decomposes so slowly that heavy mulches would in time make the soil too light for most plants. As long as only about an inch mulch is spread on each season the buildup of undecayed material should not be excessive.

Question: I would like to know what flowers are suitable to plant in flower boxes. We are building an enclosed porch with brick, and we have flower boxes along the outside front and sides, off the ground. C.Y., Illinois.

Answer: Built-in flower boxes on the outside of a brick wall should be provided with drainage. Then the selection of plants must be based on the height you want plants in the boxes, if you want vines on the front of the boxes or not, and by the amount of exposure to sunshine. If any box is on the west or south side and exposed to the full sun with a brick background the midsummer heat will be terrific.

On the north, with just a touch of sun morning and evening, or on the east with only the morning sun almost any porch box plants will survive. Start with old standbys like petunias, geraniums, lantanas, vinca vines, and coleus. With a north exposure you might add torenia, ageraturn, sultani, begonia, lobelia, and ferns such as Boston.

Question: I would like to know how to get rid of dandelions – we have so many in some places that there is nothing but dandelions. Do you think the ground should be worked up and reseeded? C.D., Minnesota.

Answer: Selective seed killers are effective for destroying dandelions especially if applied when the dandelions are growing rapidly in early spring. On the lawn use an apply the weed killer used according to the directions of the manufacturer will prove entirely effective. Working up and reseeding the lawn will do little to discourage dandelions, especially if this is done in the spring.

As a later crop emerges from seed already in the soil the spray will need to be repeated. As soon as spraying has been done to kill the dandelions seed the area with quick growing grass to fill up the bare places. Bare spots left when the dandelions are killed invite the appearance of other pests and unless you have some desirable grass coming on to fill up the areas you end just as bad off as at the start.

Question: I have a crape myrtle that gets mildew every year just before it blooms, and then the buds fall off. What can I do to prevent this unhappy situation? E.M., Oklahoma.

Answer: Mildew on the crape myrtle is due to excess of moisture on the foliage at night, lack of sunlight, and lack of air circulation through the plants. Likely the plants are too close together, crowded by larger shrubs or shaded by trees. Correct these conditions and don’t sprinkle the plants in the evening.

Question: I am very much interested in growing lilacs from cuttings. When would be the best time to take the cuttings and what type of wood, and how long should the cuttings be? What rooting material should be used? R.B., Wisconsin.

Answer: To start lilacs from cuttings, try both hardwood and softwood cuttings. Hardwood cuttings are taken any time after the leaves fall, preferably by or before January. Tip canes are cut about six inches long, buried in moist sand in a cool frostproof place, butt end up. By the middle of April the cut ends are callused and then the cuttings may be planted, right end up, in the garden. Softwood cuttings are taken late in the spring. Cuttings six inches long are rooted in sand in a closed case where the temperature and humidity can be controlled and where drafts cannot blow across the soft growths.

Question: I have an amaryllis which has flowered and now has some large seed pods. Will you tell me what I should do with the seeds and the plant? S.R., Indiana.

Answer: Cut off the seed pods and discard them. Keep the amaryllis bulbs growing, preferably by plunging the plants pots and all in the garden in a partially shaded moist place, in May. In the fall, just before frost time bring in the bulbs and ripen them off by cutting down on the water and let them rest for 6 or 8 weeks.

When you see evidence that the bulbs are trying to start up after this period of rest, repot them if necessary and start watering them again. They will soon bloom if kept in a warm, light place. You can grow new plants from the seeds but unless they are something special it is not worth the time and effort.

Question: Could you tell me something about the plant called “snow rose?” WP, Ohio.

Answer: I assume what you refer to as snow rose is the commonly called Christmas rose. Its right name is helleborus. It will grow in almost any location but prefers a place that doesn’t become too dry and with a little shade. It is practically stemless and the winter blooming flowers appear just above the soil. It usually blooms about February along about the time the witch hazel shrubs are in bloom. Often they are in bloom in or under the snow, producing greenish white flowers about two inches across. They are not showy but are interesting and once established will remain if left undisturbed for many years.

Question: My silver-lace vines do not begin blooming until October. I have been cutting them back in the fall. When should pruning be done so that flowers will come earlier? EB, Wisconsin.

Answer: Silver-lace vine, Polygonum auberti, is naturally fall blooming. A plant may be blooming in August in zone five after a growing season of approximately the same length as one blooming in October in zone two. Prune this vine in early spring, just as the new growth is starting. However, pruning done either in the fall or spring will not advance the blooming time of your vine.

Question: My passion flower vine grows all over the side of the house, but never a sign of a bud or bloom. What would you suggest? CK, Ohio.

Answer: The wild passion flower known as maypop dies down each winter. It is quite hardy and starts up in the spring and grows vigorously. It is not the exotic free flowering vine common from zone seven to the tropics. lf the vine could be protected in the spring to give it an earlier start, and thus a longer growing season, it would probably bloom.

Question: Last August I trimmed out all the black canes in my red raspberry patch. I was surprised and pleased to harvest a second crop of large berries in October and early November; some of these were frozen in the first severe weather. Should I trim out these that were left frozen with undeveloped fruit on them? JRB, Michigan.

Answer: In early spring prune back all canes to a height of four to five feet and remove entirely any diseased or weak canes. Leave the removal of fruiting canes until mid—summer, after the spring crop has been harvested. In other words, remove the black canes, those that have fruited, only once each year.

Question: What is wrong with huge bushes of forsythia that have only a few straggly blooms? JM, Missouri.

Answer: The removal of old canes which permit the new wood a chance to set flower buds should help the forsythia. Pruning should be done immediately after the flowering season and besides removing the older canes, all long pendulous canes should be headed back moderately. Often lack of bloom must be credited to late freezing weather which destroys the bloom buds but does not injure the plant. Some of the hybrid forsythias bloom much more profusely than the Old World varieties which have long been used.

Question: What kind of soil does creeping phlox require? Our plants do not spread, and they always look ratty. Should they be divided or cut back? HG, Tennessee.

Answer: Phlox subulata enjoys a light well drained soil. It must, above all, be well drained. If allowed to clamber over and around rocks in good light, this ground cover becomes a solid bed of color in the spring. It seems to prefer being left undisturbed, requiring neither cutting back, dividing or thinning. Occasionally phlox dies out in spots if subjected to severe midsummer drought. An occasional watering during the summer should be given the plants. Otherwise they need no attention. Phlox does not thrive in heavy shade, and will gradually become thin and weak.

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