Question: Hi Martha, What are the "four f's" of houseplants?

Martha: I get so much joy from my houseplants, and I love to collect them – especially those in the “Four F’s” categories of houseplants – Fruit, Foliage, Flowers, and Fragrance. Houseplants have become incredibly popular over the past few years and there are many interesting varieties available.

I’d like to share some of my favorites: how they grow and how to care for them. 

These tiny trees can deliver big doses of cheer. Tend to your citrus tree through the seasons and it will bear fruit, like this two-year-old Meyer lemon has. A layer of moss helps keep the roots moist. (see above)

HERE'S HOW TO GROW CITRUS INDOORS:

PLANT SELECTION

For a plant that will produce fruits and blossoms right away, choose a two- to three-year-old dwarf tree. Lemon trees or Calamondin orange trees, which have a high tolerance for indoor conditions, are a good choice for beginners. Buy one from a reputable nursery to avoid diseased or inferior plants.

CONTAINERS

A vessel with adequate drainage is essential. Select a clay, ceramic, or plastic pot slightly larger than the root-ball. It should have several drainage holes at the bottom. Add a shard of a broken pot or a large rock at the bottom to allow for water flow but to keep your potting mix in. Fill the saucer with stones to provide air circulation.

SOIL

Well-drained soil is also crucial. Use a slightly acidic (pH 6 to 7), loam-based potting mix. Better yet, buy premixed potting soil formulated specifically for citrus trees. I like to use Miracle-Gro® Indoor Potting Mix.

PLACEMENT

Most citrus trees require eight to twelve hours of sunlight daily. When growing them indoors, position your plants beside a south-facing window with good airflow. If necessary, supplement sun with a grow light during dark winter months. 

TEMPERATURE 

Dwarf citruses perform best when temperatures stay between 55 degrees and 85 degrees; an average of 65 degrees is ideal. They dislike abrupt temperature shifts, so be sure to protect them from chilly drafts and blazing heaters. Avoid spots near exterior doors, radiators, fireplaces, and ovens.

SEASONAL RELOCATION

Come spring, the tree can spend more time outdoors. When all threat of frost has passed, slowly acclimate your citrus tree by placing it in a semi-shaded spot for a few days. Then slowly bring the tree into the sun. It’s very important to make a slow, smooth transition to avoid shock and scorched leaves. Select a protected location in full sun with good airflow.

Patios, balconies, and terraces are all great spots. To move the tree indoors for winter, slowly reverse the process well before the first anticipated frost date.

WATER

Regular watering is key. Adding decorative mulch (such as pebbles or moss) will help reduce evaporation and retain moisture. Keep in mind that your tree’s potting soil should be kept on the dry side of moist, particularly in winter, to prevent fungal infections and root rot. Citrus trees also like moist air.

Positioning your plant near a humidifier or regularly misting the leaves with a spray bottle will help keep the foliage looking its best in dry winter months. 

FERTILIZER

From spring to summer, feed your tree every three weeks with a high-nitrogen fertilizer made for citrus. Feed half as often in fall and winter. I recommend – Miracle-Gro® Shake 'n Feed Citrus, Avocado and Mango Plant Food.

PESTS

Citrus trees are vulnerable to scale, spider mites, mealybugs, and aphids. Be on the lookout for early signs of infestation: curled, speckled, or yellowing leaves; sticky residue; and silky webs between the branches. Use the least toxic treatments available. 

HARVESTING

The time from blossom to fruit harvest varies but in general, most lemons and limes will ripen in six to nine months, and oranges will be ready to harvest in about a year. Citrus fruits ripen only on the tree and many varieties may be harvested over a period of weeks or even months.

Once the fruit has reached its full color, test for ripeness by applying a bit of pressure to the rind. A slight softening indicates your citrus is ready to pick.

Mail-order citrus, such as this Meyer lemon tree, above, will need to be repotted when it arrives. Depending on the time of year and the plant’s age, the tree might arrive bearing fruit, flowers, or just leaves.

Blooming almost year-round and brimming with lush foliage, these little wonders pack so much cheer into small spaces that every bright spot near a window seems to cry out for one African violet—or several. They are so common and so varied—some ten thousand named cultivars, all told—that it’s surprising to learn they have been enjoyed as houseplants for barely seventy years.

African violets aren’t related to true violets, Viola, but the flowers are similar in shape and, originally, were only violet in color. Today, however, African violets come in a wide range of colors: white, purples, blues, coral, peach, pinks, cinnamon, reds, and even greenish tints.

PLACEMENT

The disappointments many beginners associate with African violets—failure to bloom or outright death—are easily avoided. Flowering requires lots of bright light. East-facing windows are best, with full sun in the winter; west or south-facing windows need sheer curtains in summer, to keep leaves from scorching. African violets are comfortable indoors when you are, with the temperature a bit above 60 degrees at night and around 70 degrees during the day. If it’s too hot or too cold, you will get fewer flowers—or none.

WATER

African violets are particular about water, too. Their roots hate cold water, and their leaves spot if cold drops are left on them. Don’t let plants dry out or become waterlogged. Use the right-size pot—two and one-half inches in diameter for mini violets, four inches for mature standards—and water when the surface of the potting medium is dry to the touch. 

Repot violets once or twice a year using a well-drained, soilless medium that is light and fluffy enough that you could use a bag of it as a pillow. A good medium holds some moisture but is porous enough to let air, excess water, and growing roots move through it. I like to use: Miracle-Gro® African Violet Potting Mix.

Should you water from the top or the bottom? Either way is fine; just water thoroughly and use room-temperature water. From the top, gently move leaves aside and avoid pouring water into the crown, which can rot. From the bottom, refill the saucer or stand the pot in tepid water until the plant doesn’t drink up anymore. Never leave the pot in water longer than half an hour. Bottom-watering will lead to a buildup of fertilizer salts on the soil surface; flush these by top-watering with plain water once a month. 

I have had a wonderful time over the years propagating plants of various kinds. It gives me so much pleasure to take a leaf, or a seed, or a branch and watch it grow into a replica of the original plant. I also have found this kind of propagation enables me to share with friends and other gardeners, giving them valuable specimens of unusual plants, hard-to-find cultivars or species, especially begonias.

I first became interested in these unusual plants when I visited my maternal grandparents in Buffalo, New York. Grandma had several large begonia plants on her sun porch and her dining room windowsills. I loved the convoluted leaves, the weird colors, the scaly and hairy stems. I loved to clean up the plants for Grandma, removing the yellowed and dried leaves, thinning out the bigger ones to give the newer ones the space to grow. I used a large pair of tweezers to reach into the interior of the plant to remove old leaves so that I would not crack or break the curiously brittle but moist leaves of her odd begonias. I don't know what kinds she had, but I think some of them were certainly related to some of my cherished plants. It was Grandma who first showed me how to propagate and we did this several times over the years. I would take my rooted leaves back to New Jersey with me on the train and plant the leaves in soil filled pots to grow and grow.

PLACEMENT

For best results in much of the country, place your begonias where they receive dappled sun all day or full morning sun followed by afternoon shade. 

FERTILIZE

Feed monthly with a balanced liquid fertilizer, such as Miracle-Gro® Indoor Potting Mix, to encourage blooming right up until frost.

HERE IS A GLOSSARY OF SOME OF MY FAVORITE BEGONIA VARIETIES:

All summer we revel in our gardens’ scents. Why, then, do we send our noses on vacation for the rest of the year? Choose a few fragrant houseplants with a thought toward their bloom times and you’ll enjoy the subtle mixes and overlaps as one gives way to another.

For all this, scented plants ask very little. Houseplants can deliver nearly every imaginable aroma, so the temptations are great. A couple of cautions, however: scent appreciation is highly personal, and mixing too many fragrances can evoke a perfume-counter spritz battle. But a single favorite scent can evoke a wonderful memory. 

CARE

Winter jasmine, Jasminum polyanthum, (bottom left): Large vine with intensely fragrant, pink-budded white flowers in winter. 

Bright but indirect sun. Needs short days while buds form (no artificial light at night).

Water frequently, but they like to dry out between waterings. 

Winter-blooming varieties need cool nights. From November to December temperatures should be: nighttime, 40 degrees to 50 degrees; daytime, 10 degrees to 15 degrees higher. 

Can be pruned in spring or summer to manage size. Can be cut back hard and will re-foliate. 

Royal jasmine, J. nitidum (top left): Rich fragrance. Bushlike; grows to 3 feet. White year-round flowers.

South, or bright east, or bright west-facing window.

Nighttime temperatures, 60 degrees to 65 degrees; Daytime, 10 degrees to 15 degrees higher. 

Prune for healthy branching. 

Jasmine, J. officinale(right): Fresh scent, not musky. White flowers in spring and summer.

South, or bright east, or bright west-facing window.

Nighttime temperatures, 45 degrees to 55 degrees; Day time 10 degrees higher. 

Prune for healthy branching.

Can be pruned in spring or summer to manage size. Can be cut back hard and will re-foliate.