Adrian Higgins on planting trees ahead of a cicada year and all things gardening

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Sep 17, 2020

Washington Post gardening columnist Adrian Higgins took questions on gardening.

Hello, Mr. Higgins, We are finally ready to plant a pale pink cherry in the back garden corner (my IOU Mother's Day gift last year). It is not a huge plot so I am concerned about the span into the neighbors' airspace. To me, a cherry shouldn't be a vertical. The problem: I love the Yoshino but its 30-35 width and height make it too large. What might you recommend for Kensington's (MD) zone? Thank you!

Hello, everyone. The summer weather seems to be breaking and fall is in the air. This is the prime season for so much pleasant and constructive garden work -- at least one way to keep our minds off the current difficulties. I hope you had a chance to catch today's Local Living piece on planting now in advance of next year's cicada invasion. Also, in this weekend's Magazine, I am writing about garden design principles for small urban gardens. Japanese flowering cherry trees do become spreading beauties, but only after many years. Some have been bred for more upright use, I can think of one named Dream Catcher and another called First Lady. The Japanese flowering apricot (Prunus mume) is a smaller version of the cherry tree, but blooms four to six weeks before the Tidal Basin cherries. 

Good morning. I have a large swath of Carex that was beautiful when planted 3 years ago, but now looks like an overgrown mess. Can I dig and divide the Carex, or would it be better to simply remove half the plants? If dig and divide is the answer, is it better to do that in fall or spring? Thank you for your advice!

Carex or sedges can look scruffy. First, you need to keep their plantings somewhat groomed, with leaf litter etc. removed as needed. They also benefit from cutting back in winter before the new season's growth, which should emerge looking clean and more upright. Most benefit from supplemental watering during drought, and it was dry early this summer if you remember, though that isn't the problem at the moment. 

Good afternoon! Producer here with links to Adrian's most recent stories. Here, he looks at what the coming cicada onslaught on the East Coast means for gardeners planning to plant trees now (Brood X returns next spring). And here is a link to his upcoming Magazine story about how to plan a small, urban garden for maximum impact.

Sir, what do you recommend as a course of care for perennial flowers and ground covers during this time of excess rain? I’m in S.C. and we were wet all winter, spring, and summer. Now Sally is dropping up to 10” on us. Can I save some from drowning?

Our impulse is to put sun loving perennials in rich, moist soil, but it is amazing how better many of them do in beds that are more open in soil structure and are free draining. This is especially important in the winter, when constant moisture on the crowns can kill them off. One way to help them is to amend the soil with pea gravel, either when they are first planted or now, during perennial dividing time. I am thinking of perennials such as bearded iris, rudbeckias, echinaceas, gauras, penstemons, goldenrods, liatris, and asters, to name a few.  

Thank you for the article about next year's cicada infestation and young trees. What about shrubs? I'm getting ready to plant some hydrangeas. Should I prepare to wrap those too?

They like branches that are between a quarter and half inch in diameter, so some shrubs are targets. I don't think of H. macrophylla and serrata as being particularly tempting but I would worry more about oakleaf and PeeGee hydrangeas. 

so glad you are back!! I have an underground wasp nest beside the compost pile. how can I get rid of them and how would I know that they are really gone? I have already been stung several times.

I am not the first to reach for insecticides but the common yellowjacket is a menace and prevents you from being in the part of the garden where they have a nest. What I have done is get one of those big cans of wasp spray that shoot a jet out. During the day, I take a white plant marker and carefully place it at the entrance to the hole, taking all necessary precautions to avoid getting stung. Then I return after dark when the wasps are abed and squirt it into the hole. Once your eyes have adjusted to the dark you can make out the tip of the marker quite easily. Do not use a flashlight, which may bring them out beforehand. 

I've jumped on the trendy houseplants everywhere bandwagon, but am getting frustrated when some plants start to droop/leaves brown. The advice I get and read is either it's overwatered or underwatered. Helpful. How do I know which it is, if I, um, am not even certain what kind of plant it is? Yes, I'm new to this.

Most houseplants are best watered only after the top half inch or so of soil has dried out. The best device for testing soil moisture is your finger. Scratch around until you see and feel wet soil. The other way is to lift the pot, if it still feels heavy it probably need watering. All the pots should drain. 

Hi. I had a pretty nice garden this summer with just tomatoes, basil, cucumbers and peppers. I'm new to all of this, though. What can I plant now for fall? I live in DC and it's just a small raised bed in my tiny back yard.

If you rush, you can plant lettuce, kale, spinach, mustard greens, turnips, arugula, radishes. Carrots and beets started now should overwinter okay with some protection or mulch. 

I have two fairly young trees on my property, each about 6' tall: a red maple and a lacebark elm. Do I need to protect them against next year's cicadas? If I'm going to wrap them in bird netting, when should i do that?

Yes, those are of a size and age that probably need protecting. As I write, you will need netting of no larger than half an inch. The standard one-inch netting will be of no use. I would wrap the trees in early to mid May and keep them protected until Independence Day -- adjust that time frame based on the insect behavior. 

Besides young trees, what else is at risk from a massive cicada invasion?

Some dogs (and cats?) will eat them like candy, with unpleasant results. Large shade trees will be heavily damaged -- by the end of the summer you will see branch flagging on oaks, maples -- you name it. But there's really nothing you can do about that and by the following growing season, all should be okay. 

Good afternoon. I was lucky to receive a stem? with various leaves and lots of roots. How best to plant on my balcony? Thank you.

If you have a rooted cutting, I would pot it up as soon as possible, and keep it in a sheltered spot away from direct sunlight and wind. Might be good to bring it indoors, which you will have to do once nights approach frost time. 

I've been planning to plant 2 abelias and one aucuba in available spots this fall. Are cicadas a concern for those woody shrubs?

Abelias are really twiggy and the prospect of real damage is remote. The aucuba is perhaps more at risk. It's not going to be possible to cover every woody plant in the garden, if it were mine, I would probably not bother with the aucuba. 

Hi there, Earlier in the spring, we experimented with transplanting an offshoot or runner from a neighbor's crepe myrtle tree into our yard to see if it would take. Amazingly it did and had a beautiful flush of blooms. I haven't done any trimming or shaping so that it could get established and I could see how it grew. It's still very short and rather bushy at this point. When and how do you recommend trimming it so that it will grow into a beautiful tree? Thanks so much

You can count on it growing as large as the parent tree, in time. All tree type crape myrtles benefit from selected stem pruning when young to establish a few trunks for maturity, ones that produce a pleasant shape and are not interfering with each other. But for this little offshoot, it will be two or three years before you think about that. You now want it to get its roots established before formative pruning. It will need a sunny, open situation. 

My patio petunias have not done well - too much rain and shade, I suspect - so I want to replace them with something. Any ideas? Is it too early for pansies?

Petunias tend to be tired by September. I wouldn't hesitate in pulling them. Pansies should be all right now, they will stretch and sulk if it's much above 75 degrees but hopefully that will soon be corrected. I much prefer their daintier cousins, the violas, which are more elegant. 

I have a huge backyard garden. the green beans are really coming in so I invited my nephew, who loves green beans, over to pick some. he didn't have the slightest idea what green beans looked like growing. it's sad & funny at the same time. actually, having to pick beans threw him for a loop.

But now he knows. You've changed a life.  

Now is the time to assess what you did right (or not) with your first-year vegetable garden, so you can start planning 2021's plot -- especially if it involves mulching the plot and/or making compost over the off-season. I speak from hard-earned experience many years ago. In fact, after more than four decades we still evaluate each year's garden for tweaks to make in the coming year.

Thank you. I just read a story about all these newbie pandemic gardeners having problems with their veggies. We all have problems with veggies, each year is different. Go with it, learn from it, and accept that there are no failures, just lessons. 

I was given a few fig tree started from roots. Unsure of the variety, but they are healthy and about 2 feet tall now. Can I keep them in pots outside? If I plant in the ground, do they need protected from deer or elements? Are they ok outside all winter? Thanks!

I would take them out of the pots and if the root systems are developing well, I would plant them in the ground (assuming you're from around these parts, Pilgrim). If they're not, I would bury the pots in the garden for the winter. I'm assuming you don't have a cool greenhouse, that would be another option for raising them. They are definitely not houseplants. If you plant them in the garden, do give them a mulch of chopped leaves to see them through the winter. Farther north, folks might wrap chicken wire around them and fill the wire with leaves for the winter, but this doesn't seem necessary any more in the Mid Atlantic. 

Morning Adrian and thank you for taking questions! The house I bought in January has a young tree in the front yard that I've confirmed is a live oak. Many of my neighbors also have these trees as well. (I guess they were on sale when the builder put them in about 2 years ago?) The thing is, I know live oaks get to be huge and even if it got to be half of a typical live oak, it will rip out driveways and encroach on houses, etc. To make matters worse, they planted the trees right on top of the water line. So, long story long, is there any way to know if I have a dwarf version of a live oak? Or should I just be overly cautious and have it removed now to save a headache later? In the 8 months I've been living here, it hasn't grown from what I can tell, but again, I'm not a tree expert.

I'm not sure where you are, but live oaks are at their northern limit in DC and I don't really have much experience with them. I'm sure there are dwarf varieties but if yours isn't labeled I'm not sure how you could discern that when young. Nor do I know how easily or not they move, but if you think that's what's needed, I would check with your local county extension agent about the feasibility of that. Many trees grow to 100 feet, but only after 70 years, so you may not have to worry about its ultimate size. I'd say two years is about the cut off time for moving most planted trees, especially any with tap roots. 

Very helpful warnings about young trees but will the cicada invasion put emerging peonies, hostas, and other perennials at risk?

No, they are generally not thought of as harming herbaceous perennials. Of course, if I had tree peonies or the intersectional hybrids, I might be a bit more worried and take precautions. I'm afraid we've run out of time, but see you here again soon. Here's to a productive fall in the garden. 

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Adrian Higgins
Adrian Higgins is The Washington Post's gardening columnist. Read his latest columns and stories here and follow him on Twitter.
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