This is why an indoor rubber plant could start to turn yellow – InForum

Q: What causes a leaf of this houseplant to turn yellow? -Jeff J.

A: Your plant, which has the botanical name Ficus elastica, has several common names, including rubber tree, Indian rubber tree, and rubber fig tree. All parts of the plant contain a milky white latex, which has been tested for use in rubber manufacture, but without results. Commercial rubber products come from a different species of tree.

In its native tropics, this houseplant grows into a large tree over 100 feet tall. Its natural instinct indoors is to look like a tree. Some loss of lower leaves is common, as the rubber tree develops typical tree trunks.

There are, however, other causes of leaf yellowing on rubber plants. They would prefer the humidity of the tropics, and our dry indoor air in winter is not their best environment, and winter leaf yellowing on Ficus can be common.

By studying the photo of the soil, repotting in fresh, quality potting soil may be wise. A white crust is evident and repotting will remove salt buildup, which can also cause yellowing of the leaves. Wash the leaves and stems with insecticidal soap to limit possible insect and mite activity.

Rubber plants often grow tall and long indoors as they strive to grow into trees. If such a houseplant is less attractive than desired, I always suggest a dramatic reduction to less than 12 inches above ground level accompanied by repotting to stimulate fresh branching of the lower trunks. Providing higher light promotes the development of new shoots.

Drastic reduction isn’t 100% foolproof, but it’s worth a try if a more robust houseplant with better branching is desired.

Q: Do you have any recommendations for a shorter version of Cut-and-Come-Again Zinnias that could be planted from seed? —Robyn W.

A: Cut-and-Come-Again zinnias are an heirloom variety, probably dating back to at least the early 1900s. They bloom in a rainbow of colors, with plants reaching 24 to 36 inches tall. The flowers are about 2.5 inches in diameter and the plants are well known for their prolific production, producing many cut flowers.

Most zinnias are very productive and the flowers last as well as cut flowers. Some of the newer hybrids have taller, more uniform flowers than Cut-and-Come-Again with shorter, more manageable plant heights.

For a shorter zinnia, try the Magellan cultivar. It is a colorful mix and the flowers are larger – up to 4 to 5 inches in diameter. Plants grow to a manageable height of around 14 inches, making Magellan a colorful addition to flower beds. With its hybrid vigour, the cultivar continues to produce masses of flowers, even after harvesting for bouquets. It is available from seed companies such as Parks.

Another similar sized zinnia is the Dreamland series, also with great hybrid vigor. Zinnias are easy to start from seed and will flower sooner if started indoors from seed, rather than sowing directly outdoors. Because zinnias grow quickly indoors, delay seeding until around April 1-15 for plants that will be transplanted into the flower garden around May 20.

Q: My big old Boston fern is losing a lot of leaves and has many dry, dead branch tips when I cut off the stems that lost their leaves. Can I separate the fern and get rid of some of the dry ones. dead stuff? — Pam L.

A: Boston ferns are notorious for dropping leaves. It’s a good thing they look good, because they are definitely one of the dirtiest houseplants around, especially in the winter when the indoor air is dry.

Ferns divide well, and the older inner parts with remnants of dead stems can be discarded, and the vigorous, fresher sections repotted. To divide a fern, remove it from its pot and cut through the root system with a sharp knife, pruner or hacksaw blade.

If you have a question about gardening or lawn care, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu. Questions of general interest may be posted, so please include your name, city and state for proper guidance.