Adrian Higgins gave advice on tending your garden in the summer

Jul 11, 2013

Washington Post gardening columnist Adrian Higgins took questions on how to improve your garden in the summer..

What is the best way to mulch tomato plants: plastic, straw, other? I live in a humid midwestern state.

You mulch tomato plants for two reasons: to keep the soil moisture even and to diminish the soil splashing of spores of early blight, which cause leaf yellowing from the bottom up. (Remove diseased leaves).  Straw is great for this, a thick four inch layer would do the job. Hay can have weed seeds. In New England, folks have salt marsh hay, which is fabulous, but unavailable to most of us, along with the lobster rolls. 

I am very interested in edible gardening but find little resources/information in the mid-Atlantic area. Can you recommend demonstration gardens, classes, workshops, experts, etc. as means for learning how to grow edible plants, annuals to perennials, from fruits to vegetables to herbs?

I would check with the county extension agent for your town. The Maryland Home and Garden Information Center has a lot of free online publications by subject that are very good. Vegetable gardening is quite difficult, no one actually spells this out, because it's all about timing and soil preparation and figuring out what will grow and what won't. The very best method of learning is to do it, and with others, which means a community plot where people are friendly and willing to talk about their successes and failures. 

I've been told by a gardener that magnolia trees attract mosquitoes. Is this so?

Not really. Toys, boats, wheelbarrows, gutters, saucers, all these things give standing water for mosquitoes to breed. It is conceivable that upturned southern magnolia leaves may hold water long enough for the Asian tiger mosquito to breed, but that would be one of only many possible containers. Do yourself and your neighbors a favor by looking this weekend at all the little places where water stands, and get rid of it.

The question about violets last session got me thinking. What is the one weed that you dread the most?

The glib answer is sloth, because inaction will lead to a host of weeds. This week, the crabgrass has exploded, so get out there and pull the stuff. The creepiest weed is dodder, which is like an animal and a vampire rolled into one, its strands attach to host plants and suck the life out of them. If you don't remove the very last strand or piece, it will return. 

What is your opinion regarding the mulch with weed killer in it?

Do you mean a preemergent weedkiller, which stops weeds (and other things) from germinating? Mulch per se tends to inhibit weed germination, not sure you would need the Preen or whatever.  I have a natural aversion to herbicide, preferring to pull weeds by hand or by hoe.

I've gardened for two summers now in a 4ft garden box and haven't had good luck. My plants grow and do OK, but they don't produce many vegetables. I'm not sure how to diagnose what is going wrong since there are so many variables. I often get flowers that just die instead of turning into vegetables. Any thoughts? So far I've tried buying plants instead of starting them from seeds and moving the box to a sunnier location (though I think this might still be a problem since we have lots of trees in our yard/neighborhood that cast shadows). Thanks!!

I was going to suggest some better soil amendment until I read the bit about the sun. Very, very few vegetables will produce in shade. If you don't have six full hours of sunlight, i.e. in the afternoon, don't bother.  Plant caladiums and coleus.

I have a huge infestation of beetles that are a metallic green color. They are eating my roses and hibiscus flowers. I tried going the organic way of purchases lady bugs but that did not help. Any advice on how to get rid of these pesky pests?

This sounds like Japanese beetle or some other invasive scarab. They are drawn to particular plants that you should probably avoid. I was thinking seriously of replacing a dead Japanese maple with a corylus (Harry Lauder's Walking Stick) until I was reminded that they are absolute magnets for these beetles.  You can use pheremone lures if your property is large enough, or handpick them and dump them in a chlorine solution, but that's a chore. I've never felt that the milky spore control for the grubs is particularly effective.  

I have a huge mound of gooseberry plants. Intertwined, a real mess. They also have LOTS of fruit which I am trying to pick. Carefully. For later, do you have suggestions about how to separate the canes and prop them up on What? to grow them better? Thanks a lot.

First of all, I'm jealous, because my gooseberry bush was loaded with ripening fruit and the chipmunks ate every single one. I'm netting next year. Gooseberries are very prickly, so the first step is to get thick leather gauntlets. They fruit on year old wood, so you can't cut them back hard and keep the next year's harvest. Trim back a half or more of this season's growth, and then also take out the oldest thickest and darkest canes entirely. Use lopping shears. 

I hate, hate, hate, gardening in the summer heat and humidity, especially dealing with the never-ending task of weeding. Do you have any sure-fire methods for dealing with weeds that don't require lots of effort on my part? Thanks so much!

This is how you stay on top of weeds: You weed year round, you never let a weed go to seed, you mulch the ground to suppress germination, or you cultivate bare soil every few days. Weeding equates to work, I'm sorry. I would say that 60 percent of my gardening is weeding. And they still bear down.

My Silverqueen corn is over seven feet high, has tasseled, but as yet there are no visible ears or silk appearing. What can explain this?

Just be patient, the ears should form lower down. Water them if it turns dry. 

I have a thriving community garden plot in DC. I've been able to keep the weeds at bay thus far but know that July and August are typically troublesome. I'm interested in mulching, especially my 2 rows/18 tomato plants. I do not have a yard to get grass clippings and hay is hard to find. I'm considering newspaper and shredded bark mulch- is it safe for organic gardening? Any other suggestions?

Newspapers (unshredded) would just form a mat and a barrier. Quite safe with soy based ink. Hay can be weedy, but I wouldn't use shredded hardwood mulch -- too fibrous and takes too long to break down into organic matter for the vegetable garden. Grass clippings, by the way, aren't that good: they also mat down and form a barrier to moisture and air. Straw!

My husband and I are not gardeners of any sort. We are redoing our deck and need to have a large bush (maybe five feet long and three deep and four high) removed. Any advice on how to tackle this ourselves? Thanks!

Use lopping shears to cut off all the top growth, and then use a tool called a mattock to dig out the roots. This is a more pleasant job in the fall, when the heat has abated. 

My mom never mulched tomatoes with anything and never had any problems. It seems that because she was growing them in California, mulching was unnecessary. So, the upshot is that all soil has blight, but it can't grow in arid climates. And that's why I've never been able to grow tomatoes here without losing the plants to blight. I've always thought it was the plants.

You can grow them, but good sanitation is the key to stop it from overwhelming a plant. Remove the leaves as they discolor, and don't touch clean leaves, you can spread the disease with your hands. Again, a soil mulch will help.

Hi there! Love your columns. After many many years of city living, I just bought a house in the San Fran burbs. The house is on 5 acres with lots of landscaping, and I am a gardening novice. Are there any good books / apps that you would recommend that I can use as a reference? I need help on everything (how to trim / prune, when to fertilize, etc.), but am a true beginner. Thanks!

If San Fran is San Francisco, lucky you and the biggest challenge is the lack of rainwater. So, plant things that will survive in arid or mesic conditions (once established). Look for a catalogue called High Country Gardens. I also highly commend Edible Landscaping by Rosalind Creasy, who lives and gardens spectacularly in Los Altos. 

We have a citronella plant in a pot on our deck and I would like to create a few other plants to place in pots. What is the best way to do this?

It will root happily from cuttings, best grown indoors under lights.  Put them in a peat/sand mix, use a rooting hormone, and keep them misted until they have safely rooted.

I have two endless summer (reblooming) hydrangeas. They on the south side of my house but shaded by trees most of the day. For the past few years they 've grown tall in early June--only to be flattened droopy by the first heavy rain. Is there anything I can do to stop the droop? Prune them back hard and let them regrow?

You can prune back some of the longer stems to just above a leaf pair, and this will encourage lateral, bushy growth. Because this hydrangea, unusually, flowers on new wood, this should not affect the flowering, even if it delays it. 

What should we be planting in the vegetable garden now? (I planted a second round of zucchini last week) Is it too early to start fall crops indoors like broccoli? Also, here out west I had a lot of cicada damage to my fruit trees and blueberry bushes. Nothing catastrohic, I don't think, but lots of broken branches and lots of lost fruit. But I'll take it for the specticle of it all!

You could start broccoli indoors now, and in the garden still sow carrots, beets, beans, chard. It's a bit early for lettuce, arugula, mesclun, mustard greens etc. but it's definitely time to be thinking about it, preparing beds and ordering seed. The cicada damage will growth through next spring. Prune out damage if you can reach it. 

How can I rid my perennial garden of the invasive plant known as Bishop's Weed or Snow-on-the-mountain? It is no longer variegated, but is now all green. It chokes out everything. We are at our wit's end trying to eradicate this prolific nuisance.

This is more of a problem in northern states. I think rather than try to kill it discretely, I would try a scorched earth approach with glyphosate, but spray in early fall, when it does the most systemic damage. Check with your local extension agent for effective control.

How in the heck to keep them out of my yard, in Virginia, inside the beltway?!? I have a net fence around some of my garden and that helps but I can't do that to my entire yard. And I can't shoot them so what are my options? Do any of the sprays and things work? If so which ones? thank you.

I feel that the only effective method of excluding deer is to exclude them, with fencing. Have you checked out the Deerbusters website?

Can excess rain impact germination of seeds? I was a bit late planting my green beans and sunflowers this year and got the seeds in the ground about 3 weeks ago. So far, nothing has sprouted. We got several days of rain immediately after planting, with more since. Could that be the problem?

Seeds will rot in wet soil, this is a problem particularly in late spring when folks want to jump the gun with warm season things like corn, beans and cucumbers, and the soil is cold. At this time of year, if the wet is rotting seeds, you simply don't have sufficient tilth in your soil. 

Which climbing plants, that are not toxic to dogs, would be a good fit for a trellis that gets full sun all day? Mike in Central Oklahoma

Among perennial vines, I like clematis, cross vine and a native wisteria called Wisteria frutescens.  

Adrian, It SO good to have you back in discussions... I've usually been a lurker, but this time I've a problem. We have a nice little flower garden that's backed by arborvitae and euonymus that went through a marked growth-spurt this spring. They are over-hanging the garden a bit, and the Phlox are getting moldy, the Knock Out is pouting, even the Fuschia isn't happy. I'd like to trim both the AV and the Euon. back--- about 6-8 inches on the AV and closer to a foot or more of the Burning Bush... can I do that this time of year? I don't want to destroy my privacy screen, but really would like to get some light and air into the flowers... Thanks so much, and again... SO glad you're on line today!

Yes, now is a good time to prune things after their flush of spring growth. The arbovitae will not regenerate from stems that are cut below the current foliage, so you will have to be more careful about cutting that back. 

I have a 6 ft. tall tomato with no blossoms forming, why?

There's a joke in there somewhere but I'll refrain. The only reason it wouldn't bloom is if it is in shade. Otherwise, give it support, a stake will suffice, and you can prune out the little suckers that emerge in the leaf axils to reduce its bushiness. You might want to scratch in a little tomato feed around the roots. The season is yet young.

Adrian, thanks for the great gardening columns. I have a patch of clover in the middle of a zoysia lawn. If I were to remove the clover, is it the wrong time of the year to replace it with zoysia plugs, or does the 80 degree rule only hold for grass seed.

I wonder if you could dig out the clover (not a quick chore I grant you) and the zoysia would fill in.

I was on vacation for a week and my tomato plants are out of control. Any advice on pruning? I feel like I'm beyond the simple vs. Missouri pruning advice I'm finding online, and I'm wondering if I should cut things back fairly drastically before it gets too much farther out of hand... Thanks for your input!

Tomato plants are much easier to control before they go all jungly, with proper staking and removal of suckers. There is something to be said for a sprawling tomato plant: its  mass will produce more and sweeter fruits. We've run out of time. Thank you so much, and I'll see you here again soon.

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Adrian Higgins
Adrian Higgins is The Washington Post's gardening columnist. Read his recent story on advances in the old fashioned iris and follow him on Twitter.
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