Answers to Flower Gardening Questions

A young, cheerful couple planting flowers

TIP: Our expert gardening advisor, Kathy Bosin wants you to know, "Each US state has a Master Gardener program affiliated with a Land Grant University. Most master gardener programs offer assistance to home gardeners for questions like these, and more. Look for your local master gardeners online, and take advantage of these trained volunteers to answer your garden questions."

Q. I am going to plant some flowers in the front of my house in a flowerbed. The front of my house has full time sunshine; it is never in the shade, except at night. My question is, what kind of plants work well in all day sun and have a long bloom time?

A. Some sun tolerant annuals:

  • Dark-leaf begonia
  • Salvias
  • Marigolds
  • Vinca
  • Zinnias

Some sun tolerant perennials:

Q. What do you do with tulips and irises once the petals fall off? I don't know if I should cut them at ground level or just leave them alone.

A. For the tulips, over time the stems and leaves will turn yellow and die away. The bulbs will feed on the spent stem and it will help them to become stronger, better-blooming plants, as well as to multiply. After tulips die and all their leaves are brown and dried out, simply snip at ground level.

The plant gets its nutrients from its spent greenery, so it's best not to remove the leaves and stem until they are withered and quite dead.

The Irises are a bit different. Their stems should be cut off after all blooms have been spent. In the fall, I simply clean up any very dead-looking leaves, and otherwise leave them alone. The remaining leaves will stay green (even in wintry weather) and will help to nourish the rhizomes over the winter.

Q. Any ideas on how I might inhibit the growth of my lily of the valley without doing harm to surrounding grass and shrubs?

A. Spreading by rhizomes makes this an annoyingly invasive plant. You could install a barrier to keep it in its place.

TIP: Kathy adds, "Lily of the valley spreads rapidly and can be controlled by digging the plant out and removing it from the edges of the planting bed. Because is spreads so rapidly, keep lily of the valley in a controlled area, and be vigilant about maintenance."

Q. I dug up and saved some unique geraniums from last summer. They are growing well in pots over this winter. What is the best way to take cuttings, so I have more plants this spring?

A. Cuttings usually are taken from outdoor geraniums in late summer or early fall. Cut off 3 to 4-inch shoots, and remove the leaves on the lower part of the stem. A rooting hormone, available at most garden centers, can stimulate root production. Dip the bottom of the cutting in the powder, and shake off the excess.

Then, stick the cuttings in a rooting medium of coarse sand or a mixture of coarse sand and sphagnum peat moss (1:1 by volume). A flowerpot or wooden container that holds 3 to 4 inches of rooting medium and has bottom drainage holes is sufficient.

To allow air movement and prevent the rapid spread of disease, separate the cuttings so that they do not touch each other. Water the cuttings thoroughly. Cover the container and its contents with a plastic bag, and place in a brightly lit location, but out of direct sunlight.

It is better to keep the cuttings and rooting medium somewhat dry to decrease the chance of disease. Roots should develop in 3 to 4 weeks. After the cuttings have rooted, place each in a separate pot in good-quality potting soil without the plastic covering, and set in a well-lit spot such as a south facing window.

Q. My husband and I would like to plant some black perennials. Are there any black flowers that would bloom annually in our zone?

A. Plant Queen of the Night Tulips. There is also a black hollyhock flower. It stands very tall and regal looking, too. This is a bi-annual flower, so once you buy the original plant all you have to do is re-seed each year from the dead flower's head and you will have continual blooms each and every year.

The plant, depending on its size when you purchase it, may not bloom the first year just have very large green leaves. The second year you will have the flowers. They will grow up the tall stalk and are quite beautiful.

TIP: Kathy suggests, "In recent years, a black variety of liriope (tufted lilyturf) has become available in many markets. Planted in large masses or borders, this liriope is a stunning addition to any landscape."

Q. How hard would it be to transplant a cutting of passion flower (Passiflora alatocaerulea)? What would be the best procedure?

A. Passion flowers are usually propagated by stem cuttings taken in late spring or early summer. These should be 7.6 to 10 cm (3 to 4 inches) long and taken just below a leaf. Remove the next lower leaf and dip the end of the cutting in a rooting compound.

Place in 7.6 cm (3-inch) pots in an evenly moist mixture of peat moss and coarse sand. Cover the entire pot with a plastic bag to retain humidity and put it in good, but indirect light. The cuttings should root in 3 to 4 weeks. Keep the passion flower moist.

Q. What is the best time of year to trim azaleas? When is a good time to cut back monkey grass?

A. Azalea branches need to be selectively pruned. Use your hand pruners. Do not take hedge clippers to them. It's time consuming, but you can remove the branches at their base to eliminate the stragglers and open up bushes to allow greater air circulation and sunlight into the bush. Prune after they bloom.

Monkey grass (mondo) is an evergreen grass. It is attractive year round and does not need mowing. Often confused with liriope, both species need to be divided and thinned in the spring. Slip a knife into the plant to remove sections of plant and replant them to propagate or share with friends and family.

Old growth on both species can be cut back with kitchen shears, scissors, or, if aggressive, it can be mowed. But you don't want to remove the new growth.

Some gardeners shear or mow their monkey grass in late February or early March just before the new growth appears. You want to avoid doing this too soon so that you don't have to look at sheared monkey grass. Some people mow at the highest mower setting if the edging or bed is not too thick. Others use a string trimmer.

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