Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.
“I planted a passion fruit last year and have lots of fruits on the vines. When do I harvest the fruit?” Question from Susan of Florida
Answer: The fruits of different types of passion fruit (Passiflora spp.) vines differ in color when they are ripe. Some turn to purple, reddish-brown, or gold on the outside. When ripe, the fruit will color up from green and develop a wrinkled or dimpled exterior. Some will drop from the vine when fully ripe. If yours have changed color, but you are not certain whether they are ripe, smell the outside. It should be fragrant. Then pick one, and cut it open. The pulpy seeds within should be yellowish, fragrant, sweet, and juicy. At this point, it’s time to harvest and enjoy them.
“Winter is not over, but we have had warm spells. Daffodils are already pushing up. Will another hard freeze kill them?” Question from Richard of Winston Salem, North Carolina
Answer: You need not worry. It is not uncommon to see blooming bulbs in the snow, daffodils included. That’s because most of these early bulbs are very tough and resilient to spring cold snaps. It would have to get into the teens or even single digits Fahrenheit to really do emerging spring bulbs serious damage. So, let them be and emerge in their own time. They will bloom and flower for you with no trouble.
Most gardeners don’t realize how many beautiful milkweeds (Asclepias spp.) there are for the garden. Here are our favorites for feed monarchs beautifully.
“Monarch butterflies rely on milkweed (Asclepias spp.) flowers and foliage to complete their life cycle. Eggs are laid on milkweed foliage, a host plant for the emerging caterpillars. Chemicals in the milkweed foliage offer protection to the caterpillars, and mature monarch butterflies, making them taste toxic and terrible to would-be predators. Adult monarchs also feed on the nectar-rich flowers of these unique and beautiful plants.” -Mike Darcy
“Why do some potting soils turn green? What is it, and how can I avoid this from happening? Thank you.” Question from Angela of Taylor, Michigan
Answer: Any potting soil can turn green. That is because it is algae, or more rarely moss, that is causing the green color, and excess water on the soil surface is the culprit. A green layer on your soil means too much water. When you water to the point where the surface soil is kept wet, this invites the growth of algae. Algae and algal spores can exist in soil, water, or even air, so “clean” soil won’t keep the problem away. The best way to avoid algae is to clean up and change your watering practices.
Cleaning Up Algae in the Pot
Start by skimming off the first couple of inches of greenish potting mix on your pot tops, and refresh with new potting mix. We recommend replenishing with Black Gold All Purpose Potting Mix. It is also important that you have pots that drain well and bottom saucers for watering. If you need to upgrade your plant’s pots, it’s worth it. Pots like these will enable bottom watering.
Watering to Avoid Algae
Allow the top two inches of potting soil to become dry between watering. This will halt algal growth. Another method is to water your plants from the bottom saucer only when they need it.
“How can I grow honeyberries in zone 10?” Question from Nestor of Anaheim, California
Answer: Sadly, you cannot. Honeyberry (Loniceracaerulea) is a temperate shrub that survives in USDA Hardiness Zones 3-7. This means that it requires winter cold to complete its life cycle each year and survive. For this reason, you are unable to grow honeyberries where you live, but you can grow so many other wonderful fruits where you live, like figs, apricots, grapes, citrus, and even pomegranates. Here are a few articles that you may consider reading on fruits for your zone:
“I have a wisteria vine that is several years old. It bloomed one year ago and was beautiful. Since then it has only about 1 or 2 blooms a year. What am I doing wrong? How can I encourage blooms?” Question from Carol or Drums, Pennsylvania
Answer: Successful flowering wisterias (Wisteria sinensis) are well trained, pruned, and fed with fertilizers designed to encourage blooming. They should also be planted in full sun and slightly acid, fertile soil (amendment with Black Gold Peat Moss is encouraged). The training process takes some time and patience, but if you do it correctly, you will have a spectacular wisteria specimen that blooms well each season.
The first mental note is that wisterias bloom (and look) best when trained to have spare branching and an open structure.
Wisteria Training
Train your wisteria upright as a tree-like standard, along a stone wall, or twining around a very strong structure. Use strong ties to hold the stems in place while the woody vine grows and establishes itself. Keep in mind that wisteria stems/trunks can reach many inches across, so it is essential to give these long-lived vines strong support from the start.
Wisteria Pruning
Wisteria flower buds are large, more rounded and begin to elongate as they emerge.
To maintain spare branching, encourage the growth of just four to six main branches. Identify the main branches that you want and prune away any sprouts or unwanted stems that pop up. Prune and thin the vine in midsummer–several months after flowering–and prune it again in late winter before the flowers and new leaves emerge.
When pruning in spring, avoid the dormant flower buds. It is easy to identify the difference between wisteria flower buds and leaf buds. Dormant flower buds are rounded and large, while leaf buds are pointed and narrow.
Feeding Wisteria
Feed your wisteria with a high-phosphorus fertilizer designed to encourage flowering. Follow the manufacturer’s directions regarding application.
These steps should help your wisteria bloom better.
“I have packets of seeds from last year. One is a hummingbird mix, one a bee mix, 1 a honey bee mix etc. They’ve been stored in a plastic container in my basement, so they’ve been cool and dry. Should I refrigerate them from now until I’m ready to sow them or just leave them in the basement?” Question from Erin of Kirkwood, Missouri
Answer: Most annual and perennial seeds of temperate plants prefer similar storage conditions–as you said, they like it cool and dry. If properly stored, they can survive for several years with seed viability declining incrementally. In general, count on a storage life of around three to five years. (Click here for a detailed seed-storage chart from Johnny’s Seeds.)
Seeds store best when humidity is low and temperatures are around 40 degrees Fahrenheit. A cool, dry basement should be just fine, as long as it’s cool enough in winter and you store your seeds in a water-tight container. After planting them this spring, transition them into a well-sealed plastic container and keep them in the refrigerator because your basement will certainly be warmer through summer.
I hope that your flower seeds germinate beautifully!
“What is the best way and time to prune a Rose of Sharon?” Question from Rick ofRoseville, California
Answer: Rose of Sharon (Hibiscus syriacus) is a quite forgiving shrub when it comes to pruning. It blooms on new wood, so you can prune in the spring or later in the season. It’s your preference. This is a shrub that should not be sheared. Simply shape it by selectively removing tall, out-of-place, or awkward branches that are keeping it from looking uniform. Also, be sure to remove any crossing or old stems as well as deadwood.
This shrub tends to be weedy, which is why I also advise planting a double-flowered variety, like those on the Chiffon Series, which produce little to no seed.
Supertunia Vista® Bubblegum® (Image thanks to Proven Winners®)
“I would love to plant Wave Petunias this year, in a 1/4 wooden barrel container. Is there anything special I need to know about these beautiful flowers before I try to make them grow? Oh, and will they last all summer? Many thanks!” Question from Diane of Newark, Ohio
Answer: Wave petunias will last all summer with good care, take heat, and are one of the best choices for containers. Wave petunias were the first spreading, groundcover petunias created. The first, Purple Wave®, was bred by the Ball Seed Company and introduced in 1995 (many other Wave® varieties followed). What made them different was their ability to spread and bloom nonstop with little care and deadheading. They are tough, fast-spreading, nonstop bloomers. That’s why they are still popular today. Since then, many other groundcover petunias have been bred, some with even greater flowering power. Of these spreaders, here are the six that I recommend the most.
Supertunia Vista®Bubblegum®-Clear pink flowers and super high performance make this one of the best trailing petunias.
“Is it possible to grow fruit trees at 10,000 ft. in elevation (Rocky Mountains)” Question from Wolf of Westcliffe, Colorado
Answer: Fruit trees able to produce at high altitudes must be able to tolerate cooler, shorter growing seasons and cold winters. There are several very early fruit-bearing trees able to tough it out. Ideally, trees should also be late to flower, for spring pollination and fruit set. The University of Minnesota breeds many fruits, particularly apples, that survive under these conditions (click here to learn more). Here are a handful for you to consider.
Fruit Trees for High Elevations
Apple ‘Centennial Crabapple’ (Zone 3): a tasty crabapple good for eating fresh or making sauce that ripens in late August.
Apple ‘State Fair’ (Zone 4): a tart, sweet eating apple that ripens in August.
Apple ‘Lodi’ (Zone 3): cooking apple for pies and sauce that bears in August.
Pear ‘Summercrisp’ (Zone 4): crisp, sweet pears are produced in August.
When buying a hardy fruit tree, ask about rootstock. Some rootstocks impart more hardiness than others.
Rocky Mountain Native Fruits for High Elevations
Sometimes it pays to go native. Many native fruits naturally exist at your elevation, including bright red wax currants (Ribes cereum), which have delicious, tart red berries, serviceberry (Amelanchier alnifolia), boulder raspberry (Rubus deliciosus) and red elderberry (Sambucus racemosa). You might be able to find these in regional, specialty nurseries that sell natives. (Click here for a list of Colorado native plant sellers.)
