Adrian Higgins on summer gardening

Courtesy Ball Horticultural Co.
Aug 20, 2015

Washington Post gardening columnist Adrian Higgins took questions on gardening.

Mr. Higgins, do you know of methods to power a rain barrel via solar energy, in order to water a small vegetable and herb garden? Or anything of that nature, involving rain barrels, solar and gardens? Thank you in advance!

Greetings all. I wrote today about 10 perennials including grasses that I think we should use more. Hope you got a chance to see it. Let's get to the questions: This is Higgins Law: The more high tech an invention becomes, the greater its chance of not working. This is why the flushing toilet is such an ingenious device. It works outside the digital, electronic world. If you place your barrel a foot or two above the ground, supported on cinder blocks, perhaps, you can use gravity to power the feed. 

Here is a link to Adrian's cover story from today's Local Living, on the 10 best perennials you've never heard of.

Hi! We have raven zucchini in our garden which I understand to be to "indeterminate" producers -- producing until they don't. Our yield has dropped off in the last 2 weeks from 5-6 zucchini a week to maybe one. Are they done? How will I know?

Zucchini and other cucurbits have a way of telling you when they are done: The vines lose their vigor and lushness. Your plant should keep producing, but the way you achieve this is by taking fruit often, and before they reach a monster size. Consider this: You may be the only person on your block who wants more zucchini. Nothing wrong with that, but harvest young.  

Good morning: we'd like to plant some trees in our small DC yard to gain some privacy from our neighbors on both sides. We share a common privacy fence. Any suggestions?

Your choice of tree really depends on the space available, meaning the width available. Most people craving privacy in urban gardens make the mistake of planting big boned conifers that quickly  become contorted from lack of room and light. You should consider the Burford holly, osmanthus, Hick's yew, maybe the Chindo viburnum. Think thin. 

I grew up in the country and love plants. Now that I live in the city and have NO outdoor space, I need a little greenery in my life. But I don't really know anything about indoor plants. I'm convinced anything I get will die. Any suggestions for a west-facing room with a tree outside the window (blocking some of the light)? I'm not really into the idea of fake plant, but I don't really have much natural light, either...

You might grow a single weeping Japanese maple as a living sculpture. Beautiful in leaf, and in its winter tracery.  It will take a fair amount of shade. 

Hi Adrian, I had a 20 year old dwarfed Japanese maple that succumbed this year. My thoughts are the last two harsh winters did it in. It was the focal point of my garden bed in my front yard. It was so beautiful as the leaves were a subdued red in spring/summer but turned a bright red in autumn. Could you please recommend another variety of a dwarfed acer palmatum or a showy shrub? It should grow no taller than 8-10'. I am in Zone 7 with full sun. Thank you.

That is quite low, in medium sized shrub territory. But you might try again with an acer, or consider a deciduous azalea. Acers are highly prone to bark splitting because of winter sun heating up cold cambium, and if you go with another, I would put a trunk wrap on it from November until April. 

Hi Adrian, With some of my summer vegetables looking done, I'd like to clean out those beds and put in either some fall vegetables or flowers to keep the beds pretty and help with weed growth. What do you recommend for this time of year? Thanks, Karen

Now is the best time to sow seeds for a fall garden. I have just put in kale, collards, pak choi and scarlet runner beans. This weekend, I plan to start lettuce and other salad greens. Lettuce doesn't germinate well in warm soil, so I will sow the seed more thickly than normal, and thin as necessary. 

is it possible to grow peaches organically in our climate with its humidity and stink bugs?

A noted retired horticultural professor once told me that you cannot grow peaches in our region organically, particularly because of brown rot disease. He also gave up growing peaches because of the arrival of the stink bugs. Not very encouraging, sorry. 

I have some rosemary, mint, basil, and flat-leaf parsley growing in containers out on my balcony. Should I bring them all inside when it starts to get cold out? Last year, I grew mint in a container and left it outside, thinking mint never goes away...and it died. I'd like to keep as many of the herbs alive as I can. Help, please!

All of these except basil are hardy in our region, with the proviso that the last two winters killed a lot of stuff, including rosemary. If you want an indoor winter herb garden, I would plant afresh in containers in September (if you can find young plants) and keep the pots in a cool, bright room. 

Thank you for your always informative and helpful chats ! We have a dwarf magnolia in the front yard of our townhouse and it is doing very well. In fact , it could probably use some shaping and light pruning where it is beginning to touch a fence/ wall. When is the best time of the year to have this done ? Thanks !

You could do it now, but make sure you don't leave any stubs. Also be conservative with your trimming.  

I just moved to a new house with a very small front yard. The landscaping leaves a lot to be desired, and I'd like to replace the builders-grade shrubs with some perennials and greenery. Do I need to wait until the spring to plant? Are there plants I can put in now that will last through the winter?

Late summer, early fall is the best time to plant most shrubs and perennials, because you will get a jump on root development and plant establishment before the next growing season. Hardy plants should be fine, don't plant them too deeply, don't overwater them, and give them a light mulch.  

I planted hostas under an old, huge, magnolia with large roots a few years ago. The hostas are not doing well and I need to move and/or pot them. When should I do this? The pachysandra I planted is also not doing well. Shall I give up and just put down a thin layer of mulch, or is there something that will thrive in deep rooty shade? I live in Charlottesville.

A southern magnolia is about the worst for underplanting, along with a silver maple. It is so dense of leaf that it sucks all the light out of its vicinity. The leaf drop is horrendous. I think I might just live with a light layer of leafmold or pine fines mulch. 

I recently developed a rain garden along my property line with my neighbor. I'd like to plant some plants to create a screen. After some research, I purchased some Red Osier Dogwoods and Winterberry Holly to provide some privacy, but the deer have been decimating both types of bushes. Can you suggest a bush/shrub that will thrive in a rain garden with full afternoon sun? (Bonus points for an evergreen.)

Consider a northern bayberry (Myrica pensylvanica) or Yaupon holly (Ilex vomitoria). 

Our 2 hydrangea plants grew plenty of leaves this summer but did not flower. The same occurred with our neighbor's bush, which produced beautiful flowers previously but none the last two years. Further down the street there were flowering hydrangeas. Do you have a possible explanation for this?

Assuming you didn't prune it back in late winter by mistake, I would say the especially cold and lingering winter either killed the buds in dormancy or after the shoots emerged in March and April. Let's hope for a milder winter ahead. New varieties have been developed to bloom on new growth, which may be the types you are seeing in flower this year. 

Oh the inhumanity of it all. SIGH. I go out to harvest my 16 feet of Christmas Lima bean vines on Sunday and they are all severed near the base of the vines, classic cutworm damage. The limas were the only victims, my bush beans, tomatoes, cantaloupe vines, peppers and string bean vines were left alone. I didn't know that cutworms would hit limas this late in the game, the vines were nine feet high and full of mature pods. :-(

Hard to believe a cutworm would do this. Cutworms eat the soft tissue of emerging seedlings, not established plants. (I assume your lima beans were sown a few weeks ago). I would put it down to rabbits or voles.  

Hi Adrian, thanks for taking my question. This was the first year my husband and I attempted a vegetable garden, in northern New Jersey. My husband built raised-beds and filled them with organic soil with added compost. In a west-facing bed, I planted 4 red-pepper and 4 green-pepper plants in early May. As of this time, just one of the red-pepper plants has produced peppers. 2 green-pepper plants have very small peppers. All the plants are dark green and strong and tall, and there's little white blossoms. Just no peppers. Did I do something wrong so that the plants didn't give me any vegetables? Thanks for any advice!

First, the torrential rain of June almost wiped out a lot of peppers this year, or certainly set them back with disease and stress. What holds for tomatoes is even truer with peppers, i.e., the larger the fruit, the longer you must wait and the smaller the harvest. A lot of the smaller fruited peppers tend to be too hot for my taste, but there are a number of sweet peppers with smaller fruit and are generally productive. These include Marconi, Corno di Toro, Jimmy Nardello and Sweet Banana. If you wait and keep coddling your plants, they should fruit over the next month or six weeks. 

Every year at about this time, I struggle to prop up my overgrown tomato plants. They start out really cute in their tomato cages and then before I know it, they are spilling over outside the confines of my raised bed. Do you have a better way of controlling monster tomatoes?

The best supports for sprawling tomatoes are large, wire cages -- not the small ones you commonly find in May, but ones that are (I'm guessing here) three feet across. Some people make their own, some buy them (at a pretty penny, but they last for years). Some folks fashion them from the sheets of wire grid used to reinforce concrete slabs. Making them would be a great winter project for the forlorn gardener. 

Hello Adrian, and thanks for your time and expertise. Is there anything that can be planted from seed at this late date, and still have a reasonable chance of a fall harvest? I have beet seeds as well as lettuce and spinach seeds, and would welcome other suggestions. Many thanks for your guidance!

All three would work, the spinach may not grow fully by November, but would winter over and produce nicely in the early spring, perhaps with some winter protection. 

Other than overseeding, any other ways to help lettuce germinate such as shading from direct sunlight with a screen?

Some people start them indoors in a cooler environment and then plant them out. Alternatively, you could sow now outdoors, and if there is spotty germination, sow the gaps in a couple or three weeks when things are a bit cooler. Shade cloth might be a good approach, I haven't tried it. 

Sadly, my cucumber plant succumbed to mosaic virus a few weeks ago (and I remember thinking to myself several weeks before that, "What is this cute striped beetle?"). Now it appears that my tomato plants in the same raised bed have it. From what I've read it appears there is no hope for salvaging them. My question is what should I do at the end of the season to ensure that the raised bed is clear of the virus? The bed is 3'x8'. Also, are there preventative measures I can use next year if I see the dreaded striped guest again? Thank you!

Whatever is afflicting your tomatoes is not the same disease as that of the cucumber. If your tomatoes are blighted, you can remove the affected leaves, some people then spray with an organic sulfur fungicide, but I'm not into that. Careful sanitation, i.e. cleaning up diseased foliage, is always good garden practice. In my experience, however, it may mitigate   diseases next year but both cucumber wilt and early blight of tomatoes are endemic to our gardens. One option is to sow cucumber plants late, to avoid the pressure of the beetles. 

Is it too late to start a container garden? I only have a deck but would like to try to grow something- lettuce, beans, etc.??

No it's not too late. I would sow cilantro seeds and thin them as necessary. You could also get a late round of nasturtium, seeds sown now will form nice plants by October before frost does them in. Arugula would be a great bet, after flea beetle season. Alas, we have run out of time, sorry I couldn't get to all the questions. Hope to see you here in a month or so, when the weather will have broken, we hope!   

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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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