Category Archives: plants

Growing Luffas for Sponges

Luffa plants (Luffa aegyptiaca) are fun to grow and they make a great kid project in the garden. Although you can eat immature luffas as vegetables, most people grow them for sponges.  They are grown like cucumbers – they need to trail up a structure, they need full sun, and they prefer plenty of soil moisture. You can start them from seed easily, either indoors under lights in April or outdoors in May after our last frost.

In the summer, luffas bloom yellow flowers, about 3 inches wide. The bees love them, which is good because you need the bees to pollinate the flowers in order to get the fruit. Like summer squash, there are male and female flowers. After pollination occurs, you will see little green fruit behind female flowers.

Luffas take 90 to 120 days to mature. For sponges, pick them when the skin is yellow or brown, the fruit is lighter in weight, and the fruit “gives” if you lightly squeeze it. Cut it off the vine with about 2 inches of vine. Let it dry further (bring inside the home where it is dryer and warmer than outside). Remove the skin and remove the seeds. If it hard to remove the skin, soak in warm water for about 20 minutes. Save the seeds for next year.

The interior has a fibrous structure that is stiff when dry but softens and becomes flexible when wet. It makes an excellent scrubber for pots and barbeque grills, as well as for exfoliating the skin. You will find that your luffa is not white like store-bought luffas. The natural color is tan and may look “dirty.” Store-bought ones are bleached. You can bleach your luffas in 1 part bleach to 10 parts water for about 20 to 30 minutes.

When you start to use your luffa often in the shower, make sure it is allowed to dry between showers so it does not harbor bacteria or mold. Tie a string on one end and allow it to hang outside of the shower stall.

They can be put in the dishwasher or boiled in water to clean them. If you think they are no longer useable you can put them in the compost pile.

Luffa seeds are easy to purchase through seed companies. I rarely see luffa plants for sale at the local nurseries in this area. Try growing your own sponges this year, they are as easy as growing cucumbers!

Calculating the Last Spring Frost

Basil plants for sale in March in Northern Virginia

When planting in the spring, you want to know two things. The first is which of your plants/seeds are cool season versus warm season. Cool season plants can take a cold nip while warm season plants have to be planted after the danger of frost has passed and the night temperatures are constantly in the mid-fifties. Now, while it is cool and there is a high chance of frost, we can direct sow cool season plants such as spinach, lettuce, cilantro, kale, etc.  If we get a light frost at night they would not be affected. However, if I were to plant a basil or tomato while frost is highly likely, the low temperatures would destroy them so I will wait until it gets warmer.

As time goes by the chance of frost diminishes. Traditionally, I start my warm season plants around Mother’s Day as a marker for when there should be no chance of frost with temperatures in the mid-fifties. However, this year, spring seems to be coming early. For gardeners, there is that almost gravitational pull to get outside and start planting now.

Tomato plants for sale in March in Northern Virginia

So keep in mind the second aspect: what is your level of risk? Are you willing to start warm season plants when there is a 50 percent chance of frost? Are you willing to “get a head start” on tomatoes knowing you may have to rush out and cover them when frost is predicted that night?

Frost is predicted when air temperatures reach 32 degrees but may also occur when air temperatures are just above freezing due to open exposure to the clear night sky. Frost can be a “light freeze” at 29 to 32 degrees, which usually kills tender plants. Using the 1991-2020 climate normals from the National Oceanic and Atmospheric Administration, the National Gardening Association provides a useful chart outlining probabilities of cold temperatures by dates.

By entering my zip code in Northern Virginia, March 29 is the 50/50 point where there is a fifty-fifty chance of frost occurring. Some gardeners look for this point to get a head start knowing they may have to cover their plants.  I am more interested in being safe than sorry  — I have no desire to rush out and cover my plants so I am looking for a number lower than 50. Also, the National Gardening Association recommends using 36 degrees as the marker because frost can form at 32 degrees and then fall down into your garden even though it is 36 degrees on the ground. Using this logic, the 50/50 mark is April 9.

On April 10, I have a 10 percent chance of 32 degree temperatures. Ten days later, I have a 10 percent chance of 36 degree temperatures. As time goes by it, the 10 percent chance of frost will diminish to zero (until autumn). Because I am a low risk taker (or possibly too lazy to go outside and cover my plants), I am shooting for less than 10 percent to near zero. Therefore, I could start my basil and tomatoes at the end of April. This is earlier than my traditional Mother’s Day but keep in mind these numbers come from averages from several years ago and there is nothing to say that a freak freeze won’t occur at the end of April. So I could also be lazy and keep the Mother’s Day marker so I don’t have to change anything. Like I said, it is personal preference, you pick what you are most comfortable with or what fits your schedule.

Mt. Cuba Center Trial of Amsonia Plants

I have long admired Amsonia, especially when grown en masse. These perennial herbaceous plants bloom small blue “stars” in the spring, provide wispy green foliage in the summer, and turn a solid gold or orange color in the fall. Most are native and there are several cultivars and hybrids. Mt. Cuba Center in Delaware just published a report on their 10-year amsonia trial of 20 different types of plants, including one non-native for comparison. The 16-page report is available for download here.

Also known as “bluestars,” these perennials look like two to three-feet shrubs in the summer. They are native bee habitats, support early season pollinators, and  serve as host plants for several species of butterflies and moths. Like milkweeds, these plants produce a milky sap that deters deer.

Spring Sky, photo courtesy of Mt. Cuba Center

During the trial, the plants were virtually pest and disease free. They were grown in part to full sun on average soil and given minimal care. Supplemental water was only provided during the first year to encourage plant establishment.

The plants were rated on a scale of 1 to 5 with 1 being very poor and 5 being excellent for habit, vigor, and floral display. Not one rated a 5, but almost every plant in the evaluation was considered a top performer. The report provides a chart with the ratings, bloom time, floral display, size, foliage texture, and growth habit. The report also provides a 2023 bloom times chart as some plants bloom as early as mid-April and as late as June.

Short Stack, photo courtesy of Mt. Cuba Center

The two top performers are Amsonia ciliata ‘Spring Sky’ at 4.9 followed by A. tabernaemontana ‘Short Stack’ at 4.8. A. ciliata ‘Spring Sky’ or fringed bluestar reaches 2 feet high, blooms in mid-April to late May, and has finely textured foliage. ‘Short Stack’ is considered dwarf at 2 feet, blooms from mid-April to late May, and has more coarsely textured foliage.

The trial demonstrated that Amsonia are beautiful, easy to care for plants with three season interest. Like other perennials, they take time to get established.

This is the type of plant that attracts your attention in the fall with blazes of gold color and you think to yourself: Darn, I should have planted amsonia in the spring. So before the season starts this year, buy a few from your local garden center or check out the resources below. These companies were not in the report and do not imply a Mt. Cuba Center endorsement.
Plant Delights Nursery
Bluestone Perennials
American Meadows
Burpee
Izel Plants

A Winter Green: Arum italicum or Lords and Ladies

Yes, Virginia, there is life in the gardens during the cold winter months. Arum italicum, also known as Lords and Ladies or Orange Candleflower, emerges when most else has died down. Usually green marked with white, these arrow-shaped leaves begin to populate the ground before Christmas in my garden.  In the spring, demure, spathe-type flowers, similar to the flowers on the common, peace lily houseplant, appear. The flowers are not showy but they produce eye-popping fruit – thick sticks of bright orange berries in the early summer. By this time the leaves have receded, further emphasizing the orange berries.

Lords and Ladies is a perennial plant, preferring full sun to partial shade. It is hardy to USDA Hardiness Zone 5. All parts of the plants are toxic so wear gloves if handling and don’t eat the berries. Fortunately, deer and pests are not interested and I have yet to see any diseases.

When we moved to this house more than 20 years ago, the plants were under a beauty berry (Kolkwitzia amabelis), a large deciduous shrub about 6 feet tall. Winter sun filtered through the branches, encouraging good leaf production. However, the soil was poor, rocky, and dry – not at all the woodland conditions preferred by Lords and Ladies. This lack of moisture and nutrients must have kept them in line; they have survived every year but don’t spread. In the wild, where they may grow in moist, forest-like areas, they have been reported to be aggresive. The Lewis Ginter Botanical Gardens in Richmond categorizes Lords and Ladies as one of its “dirty dozen,” and warns gardeners not to plant them. The Maryland Invasive Species Council says it “misbehaves,” and the Master Gardeners of Northern Virginia labels it a noxious weed, further stating that it is invasive in Northern Virginia.

So while I inherited Lords and Ladies that have not moved in 20 years in my garden, I am not recommending you purchase this plant. It is still available in local nurseries and plant catalogs but just because it is offered for sale does not make it a good choice for your garden. Instead, check out Plant NOVA Natives’ list of native plant alternatives for moist shady areas.

Carex: The Wondercover

Carex woodii blooming

A few years ago, I had the opportunity to create a new garden bed toward the front of the property. It was a little too far away from the spigot so watering was going to be an issue and quite possibly deer. I wanted native shrubs but my saplings were going to take time to mature, thus leaving bare space for a few years. Having a new bed as a blank canvas is great but you have a lot of “blank” until the saplings mature.

I thought I would cover the soil with groundcovers and had heard great things about the genus Carex. I visited the local nursery and selected several Carex “Evergold” plants. In fact, this well-known local garden center only had the brightly variegated cultivars of Carex. But I liked the fact that its graceful arching leaves added color to the garden and stayed evergreen in the winter. True to form, the plants performed well despite the lack of watering. Deer have not bothered them (although they did enjoy the oakleaf hydrangea). In fact nothing has bothered the plants – they are work horses in my Virginia garden.

So when I saw the new Mt. Cuba Center Research Report on Carex for the mid-Atlantic region at a nursery trade show this past week, I picked up a copy. The 24-page publication is great. There are many detailed photos illustrating the botanical structure of the plant, photos of the top performers, and charts. The report can be downloaded from Mt. Cuba Center.

Top performer: Carex woodii

In 2017, Mt. Cuba Center’s Trial Garden staff planted 70 different types of Carex, 65 species and five cultivars (no, not my ‘Evergold’). Carex are grass-like perennials that are found in diverse habitats from wetlands to coastal sand dunes. A member of the Cyperaceae plant family, Carex is a sedge. Its stems are triangular with three edges and a solid interior. Usually their flowers are grass-like and insignificant but there are a few with larger, more pronounced flowers. The plants can be clumping or spreading. They are evergreen, semi evergreen, or deciduous in the winter. Most gardeners use them as groundcovers or as a “spiller” in a large container. They also can be used to stabilize soil, prevent erosion, and serve as a turf alternative.

Carex plants under shade at Trial Garden

For four years, the Trial Garden staff evaluated the plants for their horticultural qualities, vigor, and adaptability. They were planted in the fall of 2017 and given supplemental water for the first year to get established. From then on, they did not get supplemental water, they were not fertilized, and they only received a late winter cutback. Each plant was assessed in both full sun and shade and in average soil. The plants were rated on a scale of 1 to 5 with 1 being very poor and 5 being excellent. Top performers are in the 4.2 range or higher, but the report does caution that those plants with lower scores are not necessarily inferior. They may be useful or good performers in other conditions (more wet or more dry soils).

Top performers are listed below. The report provides a full paragraph and one to two photos for each.

  • C. woodii (Wood’s sedge): 4.7 shade rating, 4.4 sun rating
  • C. cherokeensis (Cherokee sedge): 4.7 shade rating, 4.3 sun rating
  • C. bromoides (common brome sedge): 4.6 shade rating, 4.3 sun rating
  • C. haydenii (Hayden’s sedge) 4.5 shade rating, 4.5 sun rating
  • C. stricta (upright sedge) 4.2 shade rating, 4.5 sun rating
  • C. emoryi (Emory’s sedge) 4.1 shade rating, 4.4 sun rating
  • C. sprengelii (long-beaked sedge) 4.4 shade rating, 4.0 sun rating
  • C. pensylvanica (Pennsylvania sedge) 4.3 shade rating, and 4.2 sun rating
  • C. pensylvanica ‘Straw Hat’ (Straw Hat Pennsylvania sedge) 4.4 shade rating, 4.1 sun rating
  • C. muskingumensis ‘Little Midge’ (Little Midge Muskingum sedge) 4.3 shade rating, 5.2 sun rating
  • C. albicans (white-tinge sedge) 4.3 shade rating, 4.1 sun rating
  • C. jamesii (James’s sedge) 4.3 shade rating, 3.9 sun rating
  • C. muskingumensis ‘Oehme’ (Oehme Muskingum sedge) 4.1 shade rating, 4.4 sun rating
  • C. crinita (fringed sedge) 4.0 shade rating, 4.2 sun rating
  • C. leavenworthii (Leavenworth’s sedge) 4.2 shade rating, 3.7 sun rating
  • C. plantaginea (plantain-leaf edge) 4.2 shade rating and failed to thrive in full sun and did not complete trial for sun rating

Because Carex plants are wind pollinated, there is no benefit to pollinators, but the plants are important as host plants and for habitat. Small mammals and birds eat the seeds and caterpillars of butterflies and moths consume the leaves. Toads, frogs, and turtles like to take up residence in the plants.

Looking down on Carex muskingumensis ‘Little Midge’ which has unusual foliage

The report also assessed Carex as a lawn alternative. In 2022, they did a year long mowing trial to identify which ones would be tolerant of regular mowing, grown both in sun and shade. Most were tolerant but those with medium to coarse textured foliage were not as aesthetically pleasing as mowed turf grass. Fine textured foliage looked better after mowing. The trial did not assess foot traffic which would occur in a home landscape. The top five top performers for this trial are:

  • C. woodii (Wood’s Sedge): 4.9 shade, and 4.9 sun
  • C. eburnea (bristle-leaf sedge) 4.6 shade, and 3.6 sun
  • C. socialis (low woodland sedge) 2.4 shade, and 4.6 sun
  • C. pensylvanica (Pennsylvania sedge) 4.3 shade, and 4.4 sun
  • C. jamesii (James’s sedge) 4.0 shade, and 4.4 sun

Carex crinita has pretty flowers

As I mentioned before, my ‘Evergold’ is a brightly colored cultivar that I found in a local garden center. None of these native species mentioned in the report were at the center, nor have I seen them at any other local garden center. In fact, there are many native species but you may not find them at your nursery. So if this report has you salivating for these plants, you may want to try these nurseries below. Full disclosure: these were not listed in the report and do not imply endorsement by Mt. Cuba Center.

Prairie Moon Nursery
Digging Dog Nursery
Izel Native Plants
Plant Delights Nursery

Also, if you are intrigued and want to learn more about carex plants, Sam Hoadley, who manages the Mt. Cuba Center’s Trial Garden and was responsible for this trial, will present Carex for Every Garden on February 1, 6 to 7:30 pm, virtually for a nominal fee. Register here.

Mt. Cuba Center is a destination garden, a public garden in Delaware that highlights the beauty and value of native plants to inspire conservation. I highly recommend visiting them and checking out their website for educational events and past reports on other plants.

All photos are courtesy of Mt. Cuba Center.

New Plants and Gardening Products for 2023

Hydrangea Pop Star

This week I attended the Mid-Atlantic Nursery Trade Show. Known as MANTS, this trade show is always held in January at the Baltimore Convention Center. There were more than 900 exhibitors, and there is nothing for the public to purchase, it is all wholesale. I learn about new plants and products that will be on the market for gardeners. Although it was open last year during the pandemic, this year it felt like pre-covid, like we were back in business. The event was well attended – there were crowds of attendees and exhibitors plus many local garden communicators.

Here are few new plants and products that I discovered at MANTS. You will see them at local garden centers this year, or you may be able to order them online directly from the company. Continue reading

A Gardener’s Christmas Poem

This is my gardener’s version of The Night Before Christmas. Merry Christmas everyone and thank you to those who subscribed to my gardening newsletter, asked me to talk to their organization and write for their newsletter or magazine, and collaborated with me on giveaways. It has been a wonderful year!

‘Twas the night before Christmas,
And all through the yard
The branches were bare
And the ground frozen hard;

The roses were dormant
And mulched all around
To protect them from damage
If frost heaves the ground;

The perennials were nestled
All snug in their beds,
While visions of fertilizer
Danced in their heads;

The newly planted shrubs
Had been soaked by a hose
To settle their roots
For a long winter’s doze;

And out on the lawn
The new fallen snow
Protected the roots
Of the grasses below;

When, what to my wondering
Eyes should appear,
But a Prius full of gifts
Of gardening gear;

St. Nick was the driver
A jolly old elf,
And he winked as he said,
“I’m a gardener myself.

I’ve brought new seeds
And light systems, too,
Give them a try
And see how they do.

To eliminate weeding,
I brought bags of mulch
To attract the pollinators,
I have flowers for best results.

To add to your joy,
I’ve plenty of herbs
And ornamental grasses
For your hell strip curb.

For seed planting days,
I’ve a trowel and dibble.
And a roll of wire mesh,
If the rabbits should nibble.

I have the latest books
Plus some gadgets you’ll love;
Plant stakes and frames,
And waterproof gloves.

Here are sharp shears
And a new compost pit
And, for pH detecting,
A soil testing kit.

With these colorful flagstones,
Lay a new garden path.
For the view from your window,
A bird feeder and bath.

And last but not least,
Some well-rotted manure.
A green garden year-round,
These gifts will ensure.

Then, jolly St. Nick
Having emptied his load,
Started his Prius
And took on the road.

And I heard him exclaim
Through the motor’s quiet hum,
“Merry Christmas to all,
And to all a green thumb!”

Written by Peggy Riccio, pegplant.com.

Lemon Cypress Dressed for the Holidays

As Christmas approaches, lemon cypress plants emerge, draped in holiday costumes. You have seen these small, yellow evergreens for sale at garden centers, food markets, and gift shops. Greenstreet Gardens is selling a gnome carrying a basket with a lemon cypress. The gift shop at Longwood Gardens has draped them in mini lights. A few years ago, Trader Joe’s sold Grump trees inspired by Dr. Seuss’ How the Grinch Stole Christmas. The trees were wrapped to bend and droop with a large ornament. Admittedly, these are cute and would make great gifts but then what? How do you take care of the live plant? Continue reading

Growing Luffas for the Sponges

A long time ago, 2017 to be exact, a fellow seed saver sent me luffa seeds (Luffa aegyptiaca). Although I had been interested in growing luffa for a long time, for some reason I just never got to it. Then it occurred to me that if I don’t sow these seeds, they may no longer be viable.  This year, in April, I sowed the seeds indoors under lights, much like starting tomatoes. Despite being 5 years old, the seeds germinated quickly. I transferred the seedlings into larger containers and moved them outside in May. After they hardened off, I planted them in the ground in my garden in several places.  There are some plants by a low, wooden fence, several are draped over a metal A frame, and one is climbing up a trellis. Luffas are vines with grape-like leaves that need vertical support. Continue reading

Abelia: A Workhorse of a Shrub

Abelia is an old-fashioned shrub hat is generally maintenance free.  As I drive to work, I see 4 f00t tall hedges of them on the median strip in Rockville, Maryland. They are workhorses, able to live on a median strip despite heat, cars, and exhaust fumes. Continue reading