Adrian Higgins gave advice on preparing your garden for the fall

Sep 04, 2014

Washington Post gardening columnist Adrian Higgins took questions on gardening in the fall.

Here is a link to Adrian's story on eco-friendly gardening, from the cover of this week's issue of Local Living.

I read with interest your article about eco-friendly gardening. Our problem is that our yard has become overrun with weeds. Being in the sandwich generation leaves little time for gardening. I don't like mulch, but it seems much easier to lay it down than to fight weeds all the time (actually the weeds are now poking through the thick mulch.) How can we have an eco-friendly yard that is low-maintenance too? All the weeds have gone to seed.

Weeds are a constant and the more you ignore them, the bigger the task of controlling them. It is key to pull or kill weeds before they flower and set seed. Some weeds can appear and go to seed in a matter of days. Everytime you dig or otherwise disturb the soil, you are bringing new weed seeds into play. Mulch helps a lot, though we are using way too much shredded (and dyed) wood mulch, which is harmful in the long run. Much better to mulch with leaf mold or compost, which feeds the soil. The best way to beat weeds is to grow plants in their space that you want. You must continue to weed until ground covers, etc. cover the ground. No weeding, no gardening. 

Can snap peas be grown as a fall crop?

Yes, but they should have been sown about a month ago. You could try maybe some bush beans now and hope for a mild October, but generally you sow beans in May and repeat in mid summer for a late season crop. I am growing runner beans at the moment, which will mature as the weather cools, which they like. I sowed one batch about four weeks ago and another two weeks ago, and they have grown well in the warmth of late summer. 

Loved your column. Now what can we do when local jurisdictions (Arlington, in particular) has a "property maintenance" code that prohibits "weeds" and "overgrowth"? Neither has any definition and the code is being used to cite residents for their joe pye weed, asters, asclepias, and tall native grasses.

Those definitions don't seem to be based in science and seem to be inviting a challenge. 

I completely changed my raised bed composition this year to one using one part peat moss, one part composted manure, and one part vermiculite- with great results. When and how should I amend this for the next growing season? I have heard that people who simply mix in manure have not had good results.

Organic matter alone will only give you a muck soil, you need some mineral content for a balanced soil. Keep adding the composted manure -- vermiculite is an expensive additive for general soils (mostly used in pots) -- I would add some gravel. I'm a huge fan of adding pea gravel to soil mixes. Many people dislike peat moss on environmental grounds. 

Happy shoulder season, Adrian! 1. The garden condo is looking for a tree for the 17-foot center courtyard circle, full sun, good drainage, has irrigation access. In surrounding quadrants are crape myrtle, ash, and kwanzan cherries. At the outer edges of the circle are spirea, coreopsis, and autumn joy sedum, some iris and blackberry lily. Any recommendation on a non-pink ornamental. A dwarf Japanese maple there previously died of canker. Doesn’t have to be a dwarf. Or a tree, for that matter. 2. Planted peas and lettuce last week, and I hope they survive the heat wave. Harlequin bugs can’t get enough of my dino kale. (the soapy jar nearby is getting full and disgusting) Is it worth trying to plant anything else from the brassicas, or am I just going to fight a losing battle with the bugs? Should I just yank the kale or hack it back and hope the critters go away?

It's hard for me to suggest a tree without looking at the site and available space etc. Harlequin bugs can be a real problem on brassicas, some more than others. If their populations build up to a tipping point, I would consider pulling the kale etc and going with lettuce or arugula. After all, the slugs and flea beetles need to eat too. 

We always plant a summer vegetable garden, but haven't tried veggies in the Fall yet. What would you recommend planting and when? Our tomatoes, peppers and cantaloupes are still producing, so I'm not quite ready to pull them up!

If you want a fall garden, you have to be brutal with the tomatoes and peppers and get them out of there to clear space. I am still sowing lettuce, spinach, turnips, pak choi, arugula and mustard greens. 

My garden was wonderful this summer and I have dozens of squashes spaghetti squash, butternut, sweet dumplings and acorn. I plan on eating well through the winter but what is the best way to store them. I don't have a basement but I do have a garage. Is there a way to store them (in a cover container) so that they will keep and the mice won't be tempted? Should I just keep them in the house? I know I can freeze some but the freezer is full of beans, tomatoes peppers and eggplants.

After they are cured in the sun, I would keep them in your unheated garage, on shelves if possible so they get good air circulation. Don't let them touch and check them frequently to discard those that have gone soft. They should last for many weeks. 

Adrian, I'm not sure if this is your area of expertise, but the bamboo along our back fence line (and our neighbors' yards) is destroying our lawn. We love the privacy it provides though and are thinking of installing a bamboo barrier around our current stand to keep it contained, and along our fence to keep the neighbors' out. Is this a crazy idea? If you contain bamboo to a set area, will it just become a big mess or would only enough new stalks come up to reasonably fill that area?

Bamboo barriers are serious plastic walls that are typically installed in trenches when the bamboo is planted. Putting one in after the fact may help but isn't ideal. One way to beat back running bamboo is to cut back the culms after they have grown but before they leaf out, in the spring. I have heard of whole stands of bamboo eradicated physically using a mechanical ditch digger. This would require the methodical removal of all pieces that are shredded. You would want to know the placement of underground lines before you attempted this. 

When is a good time to trim down my Holly bushes? How about Azaleas?

You could trim the hollies now, but don't shear them, that will promote fresh growth that might not be frost hardy. Azaleas generally don't need pruning unless they have become overgrown. At that point, you can cut back branches in a way that doesn't mutilate the plant but keeps its natural layering. Of course, any wood removed now will have buds for next spring. 

Hi Adrian! I'm moving this weekend to an apartment that has a small balcony, and I would love to plant a fall garden. Do you have any suggestions for easy to grow fall vegetables/herbs? Thanks!

Get a few big pots and sow some mesclun mixes that include arugula and mustard greens. You could plant some parsley as well. Rosemary at this point may not be hardy enough to make it through the winter, but would give you some fresh trimmings for the fall. Watch out for squirrels, make sure the pots drain, and water them daily until the seeds do their thing. Thin the seedlings. 

I just want to thank you for your kind words about the pea gravel the previous homeowners used to landscape with. It helped me to see the gravel in a new light & not curse it quite so robustly when i'm working in the garden.

Oh good. And remember, a garden fork is much easier to work than a shovel. 

Hi- I'm looking to add some compost to my lawn and beds this fall to improve the overall soil. I don't have enough "home made" compost so I will have to buy it in bags. Are there any varieties I should look for or stay away from?

People used to use compressed bales of peat moss, and still do, it's an effective amendment, but a lot of gardeners believe that its harvest from peat bogs is environmentally damaging. I tend to use bags of composted leaf mold or sometimes buy bulk compost from a yard (you need a pickup truck or a friend with one). Beware of offers of free compost from unknown sources, because a pile can be slow cooked and absolutely full of weed seeds. 

I have the philosophy that I want to keep as much natural material produced by my gardens and trees on the property. I shred my ornamental grasses and use for a path through a wooded area. I vacuum my leaves, which are shredded in the process, and then become mulch. My lawn is mowed with a mulching mower. This year, I've tried a weed mulch! That means I string trim them down to prevent seeding but still have a ground cover to prevent erosion. It's working pretty well but not the most attractive. Of course, appropriate trimmings go into the compost pile. I'm pretty proud of myself for trying to make a smaller footprint. I know I have more time to devote to the lawn than most folks but perhaps there's a kid you could hire to do some of these things.

This is the way to go. The leaves that fall are incredibly useful for building soil life and the idea of sending them away is daft. When the leaves outpace the ability of the mower to shred them, I blow them into a pile on the lawn and then spend half an hour going back and forth with the mulch mower to reduce them to smaller piles that I gather and put on the compost pile. Leaves that fall on plant beds can be either left to decay over the winter or, if that is too messy, blown on to the lawn and then shredded with the mower. 

Are there any mums we can plant now and they will return in the spring?

As winters have become milder, mums have reliably returned, but I suspect the last winter did them in. If you allow mums to perennialize, you should cut them back a couple of times before July to promote the bushiness you desire. 

We have been looking without success for a tree-sized native smoke tree (obovatus) species or full-sized hybrid. A local garden shop, which stocks several smoke bush hybrids, says it isn't worth carrying the species. Can you recommend any places that might have the species version? Thank you.

In my sidebar today on native plants, I list a number of nurseries that supply native plants, including a couple in Northern Virginia. I would check with them. Here's another source:

Good Afternoon. All properties bordering us have Japanese stilt grass and it is marching toward us. We find plants nestled in our grass and leggy plants in our woods. We pull all we see. Anything else we can do to protect our yard? Thanks!

Huge stands present a big challenge. This is an annual so anything you can do now to prevent it from seeding would pay dividends. String trimmer? Glyphosate? 

In the plant playground we create as designers, Mountain mint is a bully, thug, overachiever. It is wonderful and always ablaze with bees---many varieties. BUT it is a mint thus highly aggressive & spreading. I put in one wee piece and after 3 years it was 3" square. After that, I only plant it in a container or contained bed.

Some mountain mint species are more invasive than others. The one Rick recommended is muticum, which is a bit of a bully. (But think of all the questions about mulch and weeds). Pycnanthemum tenuifolium is finer and a little less aggressive. 

I had my soil tested and was told it's lacking in nitrogen. What would be the best way to tackle this, any products you recommend, and is there a better time to do this (Fall vs Spring?) Thank you.

Normally, nitrogen is not tested because it is fleeting, maybe that's what you're reading. Nitrogen from organic sources are generally more buffered than synthetic sources. What ever you use, apply it at the correct rate and take care not to get it on surfaces that will allow it to run into the drains. This is awful for rivers and the bay.

Coastal New England here. I can't get to our cabin in the early spring, so I'd like to get a jump on cutting back mophead hydrangeas, buddleias and ornamental grasses. Is it safe to whack them back in September? PS I'm delighted to find you back on WAPO every now and then. I value your approach to garden questions.

You could cut back the grasses now, I suppose, though you might lose the ornament of the seed heads. Buddleia chopping would induce fresh growth that might get frost zapped but at least would prevent seeding. Leave the hydrangeas alone, unless you want to remove a few older stems to open it up a bit. 

I was advised to plant red clover this fall for cover and nitrogen-fixing. It's been 'in the ground' for approx. 3 weeks and is barely up. Now I read online that it is a spring planting crop - - what do you think? Should I just till this in and try again in the spring? Thanks

In our growing zone (7), red clover is a winter cover crop. You did the right thing. If you sowed it in spring, it would become heat stressed as it began to grow and flower. Let it bloom next spring and then chop it down and work it in to the soil. You've reminded me, I need to get some seed. 

Good afternoon, Adrian, and thanks for your time. I have several flower gardens as well as a vegetable garden that are being choked out by zoysia grass. I weed as best I can, but several days later it all pops up again. Is there anything one can do to stave off an incursion of zoysia? Also, once a shrub is engulfed, is there any saving it? Or is the best solution to dig it out, do my best to kill all the zoysia (ha!), and start anew? Thanks so much, Adrian.

Is this your zoysia? I think I might be convinced to convert my lawn back to fescue, which is, I admit, a major task. Any suggestions, folks, on beating back zoysia? 

I am going to challenge. The ostensible reason for these rules is "health and public safety" NOT esthetics. The reasons for citing violations are "might become mosquito breeding sites" or "could harbor rats".

To me, a weedy garden is one overrun with (you name it) porcelainberry, galinsoga, nutsedge -- known noxious weeds -- not wildflowers such as goldenrod, asclepias etc. My bible on weeds is Weeds of the Northeast by Uva, Neal and DiTomaso. 

Is there an especially good time of year to have trees evaluated for trimming or removal? I have a couple that may be nearing the end of their lives. If it matters, one is a cedar and the other is a sweetgum.

You can mark branches that are dead now with a tie, if you want to remove them during winter dormancy. General signs of decline are smaller leaves and leaves that erupt from loads of suckers. (water sprouts). You may want to ask an arborist to take a look. 

When Pine trees start turning brown are they goners? We had some new ones (a white pine/mexican pine cross and a dwarf coast pine) we planted in March that seemed to be doing great all the way up until early July, and then just started going brown when things started going hot and dry. (tried to water at least once a week but not sure if it was enough).

Pines do shed their old needles by browning, but this occurs in distinct zones, not whole needle clusters. You may have watered your pines to death. Alas, we are out of time, but we'll do another chat once the fall madness begins. Thank you and sorry I couldn't get to all the questions today.

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Adrian Higgins
Adrian Higgins is The Washington Post's gardening columnist. Read his recent story on gardening lessons from the farm and follow him on Twitter.
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