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    Save the Date: Perennial Plant Society’s 30th Plant Sale is April 4, 2020, 9 a.m. – 1 p.m. at the new Expo 3 Building at The Fairgrounds Nashville. Here’s where you can find the newest varieties of perennials, shrubs, vines and annuals from local growers, along with long-time, never-fail favorites, ready for spring planting. Learn more at the PPS website.

     

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Houseplants: Share the wealth

I have three houseplants I’d like to share with a friend: a heartleaf philodendron, ZZ plant, and an African violet. What’s the easiest way to divide them?

Many houseplants can be shared. Some root from leaf or stem cuttings, others can be removed from the pot and divided at the rootball. All three of the plants named here are easily propagated.

Heartleaf philodendron: These are easy to root from stem cuttings. You can try to simply cut the tip of a stem with several leaves from the parent plant just below a node (where a leaf attaches to the stem). Remove the bottom leaves, and place the stem in a jar of water. Change the water frequently, and with luck, the stem will begin to grow roots at the node. When there are enough roots to support the plant’s growth, transfer it to a pot filled with sterile potting mix.

A better method, though, is to dip the freshly cut stem in rooting powder (usually sold in garden centers) and stick the stem into seed-starting mix. Water the mix gently, or spray with a mister, and cover the pot and cutting with plastic. Mist it daily. New growth should appear in a few weeks, and the new philodendron can be transplanted into regular potting mix.

ZZ plant: Zamioculcas zamiifolia – ZZ for short – grows from rhizomes (fleshy, sometimes bulbous underground stems), so it’s a simple task to share parts of an overgrown plant. Simply lift the plant out of the pot and separate the rhizomes by pulling them apart gently Replant the rhizomes into clean pots with new potting mix, water, and maintain as usual.

You can also propagate ZZ from plant cuttings. Plant the cuttings in potting mix that drains well, water lightly, and place the cuttings in a warm, brightly lit area. This is a slow-growing plant, so it may take weeks or months before the new plant shows signs of rooting. Whatever you do, don’t overwater. ZZ is usually happier on the dry side.

(For more information about Zamioculcas zamiifolia, check out my article How to Care for a ZZ Plant at HGTV.com.)

African violet: These sweet little plants are easily shared by rooting petiole (leaf stem) cuttings. Cut a healthy leaf with its stem from the parent plant, trim the stem to about and inch or inch-and-a-half long, and stick the end of the stem into damp seed-starting mix. You may want to cover the pot with plastic to keep the cutting humid and warm. In any case, check daily to make sure the soil remains lightly moist. In a few weeks, you will see tiny plantlets emerge from the soil. At that time, you can transplant it to regular potting mix and cut away and discard the parent leaf.

This is a good technique to use when you accidentally knock a leaf off your established African violet. More plants for your friends, and for your own indoor garden!

Grow Siberian iris from seed

I have several Siberian iris pods that have dried and split and produced seeds. Can I plant them to grow new irises? When is the best time to plant?

Siberian iris croppedAfter the irises bloom in the spring, they may form seed pods, and those ripe seeds (which should be dark and shiny) can be saved and planted to grow new irises. But they require specific conditions to germinate successfully, including a period of cold weather, so the best time to plant iris seeds is in late fall and winter.

Iris experts suggest two ways of germinating iris seeds. This information comes from Margie Valenzuela of the Tucson Area Iris Society and Sally G. Miller at the Dave’s Garden online community of gardeners:

Soak the seeds in water for at least 48 hours, or for several days, changing the water every day. This causes the seeds to plump up and allows them to germinate faster. Plant the seeds about a half-inch deep, about a half-inch apart in a planter box filled with seed-starting potting mix, and keep the soil moist (but not wet) at all times. You may want to cover the container with wire mesh to keep squirrels from digging in the pot. You can also plant the seeds directly in the ground this winter, in a prepared bed. When they begin to germinate, iris seedlings look a bit like grass, but the leaves soon acquire their typical flattened growth pattern.

Other experts provide information about growing seedlings indoors, under lights. They still need a period of chilling – about 12 weeks in the refrigerator, after soaking the seeds in a sterilizing solution of one part bleach and ten parts water. After they’ve had their chill, plant the seeds in seedling mix and grow them under fluorescent lights indoors, moving the seedlings to the prepared garden bed as weather permits, and keep them well-watered during the first year.

Irises grown from seed may not bloom the first year. And when they do bloom, you may find they don’t emerge as the exact plant that grew them – they likely will be interesting hybrids, fertilized nature’s way by bees and other pollinators.

The beauty of beautyberry

A friend gave us a cutting from a beautyberry shrub a couple of years ago, and the new shrub bloomed and produced berries for the first time this year. When can we take cuttings to plant more of them?

beautyberry 2You can increase your plantings of American beautyberry (Callicarpa americana) by taking softwood stem cuttings in summer or fall, according to the USDA Plants Database. Cut 4” – 6” long stems, dip the cut ends into rooting hormone and stick them into potting mix or other rooting media. Water the cuttings and cover them with plastic to keep the material moist. Roots should develop in a few weeks.

After rooting begins, remove the plastic for longer intervals each day for a week or so, finally removing it permanently. Plant the rooted cuttings and water them well.

The mature fruit — those beautiful berries — can also be planted in the fall to germinate next spring.

Beautyberry, which also goes by the names sourbush, bunchberry and French mulberry, is an easy-to-grow perennial shrub that is native to the U.S. Several special of birds are drawn to the purple berries in late summer and fall, as are squirrels, raccoons, possums and deer.

And interesting note from the USDA Plant Database: farmers in the early 20th century crushed the leaves and rubbed them on themselves to repel mosquitoes and other biting bugs. Native American cultures also used the roots, leaves and branches for medicinal purposes, to treat malarial fevers, rheumatism, stomach aches, dysentery and colic.

October in the garden: Click here for a list of October garden tips & tasks.

Dig and divide Daisies, Susans

When is the best time to divide and replant black-eyed Susans and Shasta daisies, in the fall or spring?
black eyed susans

If Shasta daisies and black-eyed Susans are crowding out other plants in a perennial bed, you can dig and divide them in the fall to rejuvenate them.

Both have a tendency to grow thin at the center of a clump of plants, and especially for black-eyed Susans, garden author Troy Marden, in his Southern Gardener’s Handbook, suggests digging vigorous plants from the edges of the clump and transplanting them back to the middle, so that the clump remains full.

Editors of the Southern Living Garden Book suggest this method for digging and dividing perennials: use a shovel or spading fork to cut into the soil 6 – 12 inches beyond the plant’s perimeter, then dig under the roots and lift the clump out of the ground. Tease some of the soil from the root ball, then pull the clump apart, or cut it into sections using clippers or a sharp-bladed shovel. Trim damaged roots, stems or leaves, then replant the divisions.

If you’re moving divisions to a new bed, it’s best to have the bed prepared before you dig them up. Both plants thrive in full sun in well-drained soil that is kept evenly moist. Black-eyed Susans are especially durable once they are established.

Plan to divide crowded daylilies this fall

The daylilies in our garden beds are beginning to crowd out other plants. Can they be separated and thinned out?

DayliliesExperts at the National Arboretum and the American Hemerocallis Society Society suggest thinning clumps of daylilies every five years or so. Repeat blooming varieties (such as ‘Stella de Oro,’ ‘Happy Returns’ and others) tend to form larger clumps, and may need to be divided more often. Early spring and fall are good times to take care of this task.

When the time comes to divide the clumps, use a garden fork to loosen the soil and pry the clump of roots out of the ground. Divide it by pushing two garden forks back to back down into the center of the clump, then push the handles apart to separate the roots.

To replant the divisions, dig a wide, shallow hole and place the rootball into the hole. Backfill with soil and tamp it into place, then cover the soil with an inch of mulch. Water thoroughly. You can cut the foliage back to about 12 inches.

(Stella de Oro? Stella d’Oro? You may see it spelled either way. I use the same spelling as the American Hemerocallis Society, which provides loads of information about daylilies at its website.

Garden seeds: How old is too old?

QUESTION: How long do seeds last? If a seed packet says “purchase by 12/11,” would the seeds still be good for this year?  I’m looking at sunflowers, green beans, and other summer vegetables.

Packed for 2011. Still good? Probably, if they’ve been kept dry and cool.

It’s probably a common experience among gardeners to find packets of last year’s seeds – or seeds from two or more years ago (opened or unopened) stashed in a forgotten corner. They look too good to throw away, but is it worth wasting time and space in the garden to plant them if they may not germinate?

The good news is that many seeds last beyond the “sell-by” or “packaged for” date that’s printed on the packet, especially if they’ve been kept in favorable conditions – dry and reasonably cool. Seeds of parsnips, onions and leeks are among those that will only be good for a year, but seeds of most of the common garden vegetables can last two, three, or some, even five years. Here’s a short list from vegetable researchers atOregonStateUniversity:

Two years: sweet corn, lettuce, parsley, peppers, chard.

Three years: Bush and pole beans, carrots, cucumbers, melons, peas, squashes, tomatoes.

Four years: radishes, turnips.

Seeds of annual flowers are generally good for 1 – 3 years, the researchers say; seeds of perennials can last 2 – 4 years.

You can test the viability of a packet of seeds by placing a few in a moist paper towel in a warm room for a few days to see if they germinate. Seed Savers Exchange provides detailed instructions here.

If you have seeds left at the end of the season, the best way to store them is in a sealed jar with something to absorb moisture (rice or powdered milk are two suggestions). Store the jar in the refrigerator or a cool area in the house, such as a basement.

 

Good luck with ‘bamboo’

QUESTION: I have a “lucky bamboo” plant in a pot of water with pebbles that looked great for awhile, but now it has grown big shoots out of each of the stalks. Can I cut off these shoots and re-pot them?

The first thing you need to know about lucky bamboo that it’s not bamboo at all, but a plant in the genus Dracaena (specifically, D. Sanderiana). Its close kin includes two other popular houseplants: corn plant andMadagascar dragon tree.

Growers of this easy-care plant suggest not cutting it from the top, but you can remove the extra shoots from the stalk with a sharp knife. Cut it flush with the stalk if you don’t want another shoot to grow in the same place. If you do want a shoot to re-emerge, cut it about 1/8-inch out from the stalk. You can try to root the cut-off shoots in water: Dip the ends in rooting hormone powder and let them dry overnight, then place the shoots in water. Eventually, new roots may grow. You can grow lucky bamboo in water or in soil.

These are relatively low-maintenance plants, but you do need to pay attention to the water they’re in, and add water as it evaporates so the roots don’t dry out. Every week or so, pour out the old water and add fresh, preferably filtered water, or tap water that you have allowed to sit out overnight.

Keep lucky bamboo out of direct light and away from extreme heat or cold, and feed it every couple of months with a very dilute solution of plant food (about 1/10 the recommended strength, plant care specialists suggest).

 

Sweet surprise: sweet potato vines

QUESTION: The ornamental sweet potato vines I grew in large pots last summer produced potatoes – to my surprise! Can they be replanted to produce vines next year?

Sweet potato vine (Ipomoea batatas) ‘Blackie’

Yes! The sweet potatoes that are grown for their ornamental vines don’t have much taste, but U.T. Extension agent David Cook says you can save the tubers to produce the same foliage next year. Here’s how to do it:

If the potatoes haven’t already frozen (and by now, you may find that they have, unfortunately), dig them up and store them packed in straw in a dry, cool place. When the weather begins to get warm again, the tubers may begin to sprout. Cut them into sections just as you would cut a seed potato, with at last one “eye” per section. Allow them to dry for a few days, and plant them in the ground after the frost date has passed (mid-April here in Middle Tennessee).

Ornamental sweet potato vines come in a variety of fancy-leafed “flavors.” ‘Blackie’ is an easy-to-find favorite, with purplish-black, deeply lobed leaves. ‘Ace of spades’ has heart-shaped leaves. ‘Tri-color’ is variegated with green, white and pink foliage, and the variety called ‘Marguerite’ has golden-green leaves.

The vines grow fast, and are a striking addition as a “spiller” in a container, draping elegantly over the sides. I learned last summer that rabbits find the leaves tasty. If your garden has a resident rabbit (as mine does), you’ll find the vines will start to disappear, so be warned.

Hellebores: winter in bloom

When can hellebores be planted or divided?

Hellebores can be a nice surprise in the garden in late winter, when everything else out there is still asleep. They are tough plants with evergreen foliage and flowers that bloom in winter and last well into spring. Even when they are blooming, they are not fazed by frost or below-freezing temperatures, and they will emerge from a mantle of snow bright and fresh as when they bloomed.

You can plant hellebores in spring or fall. They can be dug up and divided, but they may take a year or two to get re-established. Sometimes they self-sow, and the young seedlings can be dug up and transplanted in spring.

Gardeners often think of them as shade-loving plants, but they can also do well in sunny areas. They are happiest in well-drained, alkaline soil with plenty of organic matter. Southern Living Garden Book suggests fertilizing once or twice a year.

Helleborus is the botanical name. H. orientalis is often called by its common name, Lenten rose, but there are several varieties and hybrids that have different traits. To see photos of different varieties, check out the online resource hellebores.org.

 

New plants from old rosemary

QUESTION: I’ve recently moved a large rosemary plant from a friend’s yard to mine. It has not liked the move. I’ve started rooting some cuttings in water, and they seem to be doing well. How long should I let the roots grow before moving them to dirt? Do you recommend potting them in soil in a clay pot during this heat until they mature? Can I save what is left of the big plant in my flower bed?  — Charles W.

It may take several weeks, but stem cuttings of rosemary can root in water.

Good idea to root cuttings from the rosemary plant. Once they get a good growth of healthy roots — six to eight roots per cutting, 1 to 1 1/2 inch long — put them in a container in good potting soil. If they’re going to be outdoors, I don’t recommend a clay pot because in this heat, clay dries out very quickly; plastic containers may hold the moisture longer. Place them in a protected spot out of direct sun until they become acclimated to their new environment. If you have enough cuttings and the roots seem big enough, you could try to plant cuttings directly into a prepared bed in the garden. Wherever you put them, make sure they have good drainage, and get adequate moisture while they are acclimating to their new home.

If the big plant already looks like it’s dying, it may be too late to save it – rosemary is notoriously hard to transplant. But here’s one thing you could try: cut the branches back, which may allow the plant to put more energy into establishing new roots instead of maintaining a lot of top growth. This may not work, but it’s worth a try.

This is a good place to describe the process of propagating plants from cuttings. Start by cutting off 2 – 3 inches of the tender top growth of an established plant. Remove the leaves from the bottom end of the cutting, and dip the stem in a rooting hormone powder (such as Rootone). Place the cuttings in a damp rooting medium that drains well, and make sure the medium doesn’t dry out.

With rosemary cuttings, roots should form in about three weeks, and can be planted into individual pots. Pinch out the top of the cutting to encourage branch development.

Or, stick a few cuttings of new growth in a glass of water and wait for the roots to appear. Strip the leaves that will be below the water line, and change the water frequently. In fact, it’s a good idea to change the water every day. When roots develop, plant the cuttings in potting soil.

More from the garden:

The Creeper returns, at Turning Toward the Sun: A Garden Journal.