Adrian Higgins gives advice on grooming your garden in the fall

Sep 22, 2011

Learn how to make your lawn look lush, and get fall gardening advice.

Should bleeding heart plants be cut back for fall? Can they be moved during fall?

Greetings everyone. I wrote about lawn repair and renovation in today's Local Living section, but feel free to ask questions about other gardening topics at this really busy and beautiful time of year. Bleeding hearts can be divided by lifting and separating (sounds like an item of intimate apparel) the rhizomes. The hard part is that the top growth usually dies back in June in these parts, so finding them may be a challenge.

Thank you for your excellent and timely article on lawn care. We have a shady backyard with highly compacted clay soil that I'd like to renovate. I know I have my work cut out for me, but I'm going to give it a try. My question: Is there a particular brand of fine fescue that you recommend for our shady conditions?

The University of Maryland extension folks have a great publication on recommended grass varieties. It's called TT-77 and includes named varieties of fine fescues. These include Berkshire, LaCross and 7 Seas. Finding retail sources will take some effort, I'd say. There's nothing wrong with trying to keep a lawn going in a shady back yard, but you have to recognize that it will be a continual effort.

Adrian, due to loss of a few trees, my former shade garden gets 2.5 hours of sun starting at noon in high summer. Some plants go dormant but my hostas and epimedium burn. As I replace dead plants with more sun tolerant ones, do you have a suggestion for providing shade in the meantime? Could I do something artful by making an umbrella with shade netting?

That doesn't seem as bad as a whole afternoon of unshielded sunlight. The hostas will take the sun if they are adequately watered, but I would find a shadier spot for the epimediums. Now would be a good time to move either perennial.

Adrian, any vegetables that I can plant now, either from seed or transplant? I seeded beets, lettuce and arugula just after the rain stopped. Any ideas (collards)?

All of those will be good, perhaps the beets may not mature fully before winter, but you could eat the greens and let them do their thing in  the spring. I have just sown  lettuce and radish seed, as well as swiss chard and loads of mesclun mixes.  The soil is warm and moist, and germination is rapid.

When is the best time for those of us in the D.C. area to start laying new grass seed? I'm always afraid that I'll start too late, and the grass will be damaged by frost.

That was the topic of my cover piece in Local Living today. Fescue seedlings will take several degrees of frost once established, and then go winter dormant. Start them now so that they are robust before the cold of December.

Hi, Adrian. I love these chats and wish they were still weekly! Sometime in early August, I noticed that my red and white striped impatiens were blooming as solid red. Then right after Hurricane Irene, all the flowers were gone from the banks of flowers that were most exposed; those have now developed spots on the leaves and are thinning, so I don't think it was just wind that blew the flowers off. Other impatiens nearby, but slightly more protected, seem fine. I'm guessing that the two problems (loss of stripes and non-flowering/spots) are unrelated, but wonder if you have any idea what's causing either? Thanks!

The red flowers are either a reversion on a striped plant, or are seedlings that have grown up on their own unnoticed. Check to see if a given plant has all red flowers (a seedling) or just has some (reversion).  Impatiens cycle in and out of bloom, and the loss of flowers is probably a low point in that rhythm.

So glad to see you are back!! There is a large wooded area behind the townhouses. Deer live there and come out to eat everything I plant in my backyard. Any suggestions for this small space with full sun? Thanks!

Generally, deer don't like plants with silver foliage or strong oils. I wonder if mountain mint is on their dislike list? That would make a fabulous ground cover for you. Get a few plants and set them out and see if the deer eat them. The botanic name is Pycnanthemum.

How do we put the asparagus to bed for fall? Cut the fronds back? Mulch with straw?

Cut the foliage when it begins to turn, if it's green it's still making food for the roots. I wouldn't mulch, for fear of harboring the asparagus beetle.

I'm having a professional renovate my front lawn and then duplicate it for the rear areas. He's said he's using a tall fescue as seed. What is a good variety for me to use in back? It's sunny in summer from 11 a.m. till dusk. Thanks.

Again, the Maryland tech sheet gives varieties known to excel in our region. Here's the url: http://www.hgic.umd.edu/content/documents/tt77_000.pdf

Sorry, a bit off topic. I have a 4-foot by 4-foot beauty bush I'd like to transplant. Can I transplant it now?

I would worry that the root system on an established plants wouldn't favor that, but if you have to move it, now is the time. You don't say why you need to move it. This is not a widely loved shrub, (kolkwitzia, not to be confused with the other beautyberry, callicarpa), so you may want to pick something else. Kolkwitzia blooms on old wood, so any removal of branches now, by the way, will affect next season's flowering.

Hi, Adrian. I got an Elaeagnus pungens on sale a few weeks ago, but then started reading how horribly invasive they can be. My parents planted a few in their yard in Richmond that seemed very durable and looked nice without spreading. What's your take: good or bad?

This was once a highly favored shrub for screening and what have you because of its silvery foliage, robust habit and incredible fragrance. It's a problem as an invasive along with other such former stalwarts as Bradford pear and thunbergia. I've seen it used as an espaliered plant in a walled garden. I'd have to call it a villain and advise against it. The birds spread it by eating the berries.

My question actually concerns next spring. We are considering redoing our backyard to add a grassy area, which it currently lacks. However I'm concerned about an eternal battle-fighting crab grass. Is there anything we can do here?

Yes, both regular pre-emergent is effective, as is the organic corn gluten. Crab grass germinates between late April and early June, so it's important to lay this stuff by mid April. You can also put it in garden beds where crabgrass has been a problem, though it will inhibit the germination of desirable annuals such as poppies and larkspur.

As I have done for several years running, I planted dahlia tubers that I'd dug up the previous year. They always bloomed prolifically, until this year. I have five plants, with only a few flowers. They are in the same locations as before (so same light and drainage). Tubers I shared with a co-worker are also not blooming well. Last year, I had a second burst of blooms after a heavy pruning, but that didn't work this year. Any idea what I did this year? More importantly, is there anything I should do in storing or planting the tubers that would promote better flowering next year?

I would worry that your stock is virused, and I would simply start again with fresh tubers in the spring. I have had good luck buying varieties from Swan Island. http://www.dahlias.com/

Welcome back professor. I hope the deluded ownership of the Post has come to their senses and figured out that we gardeners of the DC area need your advice again, every week. (I mean, you, Warren Brown and Gene Weingarten are the main reasons for being for the chats, IMHO.)

Raised beds. I would like to build a couple for my veggies and maybe an asparagus bed I'd love to have. However, I'd rather use cedar over any-old-pine that I could get at Lowes/Depot that would just rot by next week. Where is a good place to source that lumber in this area aside from special-ordering from Strosniders? The big-box stores just seem to have wiped out choices in such an area.

Thank you for your kind support. I have found cedar planks at Lowe's, but not Home Depot, curiously. I have also found it at salvage lumberyards. I've also decided to use plain old pine lumber to frame beds, recognizing that I may have to replace it every three or four years.

We re-sodded our lawn in the early summer. While there is some grass, it's somewhat thin. If we aerated it and then over-seeded, would the aerator pull up the pieces of sod?

No, it should have rooted by now. 

Hi Adrian. Thanks for the article today. I live in Reston, and I have too much shade on 1/4 of my (small) lawn to grow grass effectively. In light of that, can you give me three to four decent alternatives for this area in terms of green ground cover? I prefer something that will work great in this climate, my kids can walk/play on, is low maintenance and is not so tall that snakes (yes, there are some out here!) or other varmints can hide in. Thanks!

I don't know of any living alternative to lawn that can sustain people walking on it, other than occasionally and lightly. Chamomile and thyme will take a little foot traffic but not much. You may want to frame a play area and simply mulch it, and then plant ground covers around it, things such as leadwort, epimedium and hellebores.

Do I need to overseed though my grass looks pretty thick and healthy, or should I just aerate and fertilize? When does a yard need to be de-thatched? Thanks.

Fescues don't need dethatching as much as bluegrass, but any time the thatch layer is thicker than half an inch, you should rake that out. If you take a thatch rake and work the lawn, you will get a good idea quickly whether this needs doing by the amount of thatch that is disturbed. It wouldn't hurt to aerate, fertilize and overseed.

Thanks for that info about bleeding hearts dying back in June here. I keep thinking mine has died, but it came back beautifully.this year. I mark its location with a marker and am hoping some ground covers will disguise the hole. Have you grown fava beans? I never seem to get huge harvests or get the timing right, but I am trying again this fall.

Bleeding hearts are a lovely sign of spring, and are effective in mass plantings. Fava beans are a bit tricky. If you have a good microclimate (inside the Beltway) you can grow favas through the winter for spring harvest. They will die below about 18 degrees, but if you can keep them going, they spring back beautifully and productively in April and May. I would sow some in early October but keep seeds in the fridge for spring sowing if the winter is bad. They do best if you can grow them through the winter because they really dislike the heat of May and June.

Hello! We moved in to a house with zoysia grass. How do we prepare it for the fall? Also, there is currently clover growing in about 1/5 of the yard. What's the best way to remove that? Thank you!

You don't fertilize zoysia in the fall as you would fescue. It is fertilized in the spring. Just keep it mowed until it stops growing with the frost. You can deal with the clover in the spring, using an herbicide labeled for it.

I tried growing tomatoes this year and only harvested a handful. I think the problem is not enough sun. Is there another vegetable I can try instead next year?

If you don't have at least six hours of direct sunlight, growing vegetables is a frustrating exercise. You could try some leafy greens and carrots, but you really do need lots of sun to grow edibles.

Hi! I live in central North Carolina (Raleigh) and was thinking of renovating my lawn. (Currently it is all bermuda and weeds.) A landscaping professional offered me an opinion yesterday that I should just leave the bermuda because there was no guarantee it wouldn't "grow back through" fescue, even after digging up and re-sodding. Also, he noticed our neighbor's lawn had bermuda creeping through, which he thought would also eventually infiltrate our lawn. Any thoughts on this? Have you heard of bermuda re-emerging even after killing it and re-sodding with a different grass? Thanks! (FWIW, I'd be comfortable leaving the bermuda, but it seems like most people hate it. My main issue with it is I just don't know how to rid it of all the weeds, especially the low creeping weeds the mower doesn't catch.)

The point he's making is that even if you kill or dig out weedy bermudagrass it will probably grow back. That's true, but you can stay on top of it in a fescue lawn with a bermudagrass herbicide and by pulling it as it grows. Alternatively, you could grow an ornamental strain of bermudagrass where you are.

What should I be planting for fall?

I would grow perennials, shrubs and trees. All of them will put on a lot of vital root growth between now and December which will make them especially robust next spring. Also, if you are selecting a shrub or a tree for fall color, go shopping in mid to late October and see how they color up. There is a lot of individual variation in such things as maples, fothergillas, witch hazels, crape myrtles, viburnums -- all those plants we use for fall color.

We simply used concrete blocks (8"x8"x16") that we found lying around our property to frame our raised beds (holes obviously not sideways -- LOL!). Is there anything wrong with this?

Not if you have beds that are large enough. I'd worry about dislodging them as I worked the beds and turned the soil prior to seeding, but if you are careful, I think they'd be fine.

Hi, Adrian. For the last three years I've had a plot in a community garden (in Maryland). The first year I had absolutely bumper crops of tomatoes and peppers, but I've struggled since then. Last year the peppers really seemed to struggle in the heat. I barely got any at all. Many of the tomato plants succumbed to blight early on as well. This year was better, but while the tomatoes started out fast, by mid-summer they were showing signs of disease infestation again. I had to pull them up by the end of August (while my parents in NY still have tomatoes on the vine!). My peppers were slow to mature but were hanging in well, but have suddenly wilted (despite all the rain). I'm perplexed at how to control this. I know you're supposed to rotate where you plant tomatoes/peppers/eggplants, but with a limited size plot I've run out of spaces where none of these have been planted yet. Is there anything I can do to prevent disease from taking over my plot again next year? Thanks!

The reality is that tomatoes take a nose dive by late August. And it sounds as if you have tomato/pepper disease build up. I would skip them next year, and try beans, corn, okra, sunflowers and things like that. Cukes and squash have their own problems, and it sounds as if you need a year free from high maintenance plants to reaffirm the value of it. I also love malabar spinach as a heat loving green. Folks, we've run out of time. Thanks so much for joining me. I do Tweet a fair bit, much of it inane but heartfelt. Get digging!

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Adrian Higgins
Adrian Higgins is the Washington Post's gardening columnist. Read his latest story on how to improve your lawn and more of his stories here.
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