Got a chronic case of green thumb? Like getting your hands dirty? Adrian Higgins , garden editor for The Post's Home section, is here to help. Higgins is a firm believer in "tough plants for tough times" -- the varieties that combine good looks with stiff resistance to disease and pests. He currently rules over a garden filled with spring bulbs, daffodils, ornamental onions, perennials, asters, yarrows, hostas and day lilies. Higgins, an avid organic gardener who believes chemicals are a last resort, also tends his own herb and vegetable gardens where he grows peas, garlic onions, lettuce, rhubarbs, radishes, carrots and more.

Catch up on previous transcripts of The Garden Plot.

Higgins is the author of two books, "The Secret Gardens of Georgetown: Behind the Walls of Washington's Most Historic Neighborhood" and "The Washington Post Garden Book: The Ultimate Guide to Gardening in Greater Washington and the Mid-Atlantic Region."

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Washington, DC: Leaves will be falling soon, so do you recommend running my mulching mower over the leaves to fertilize the grass, or raking the leaves up?

Adrian Higgins: The leaf drop becomes too great, generally, for a mower to stay on top of it. I use the bag on my mulching mower to shred and collect the leaves, which I dump in my compost bin. When the leaf drop becomes huge, I rake or blow the leaves on to a tarp, drag the tarp and leaves leaves to the area of the compost bin(s), remove the tarp and then shred the leaves with the mower before adding to the compost. Any matter that is added to compost will break down much more quickly when it is chopped up because you expose more surface area to the microbes.

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Arlington, Va.: Good morning, Professor! My zukes and squash were victims of the squash borer this year. Is there anything I can do to prevent this from happening again next year? Thanks!

Adrian Higgins: It depends how fervent you want to be. One tactic is to sow the plants in June and early July instead of May. Another is to wrap the young vines in aluminum foil a few inches at the base of the stem. Another is to paint the stems with an organic insecticide before the moths appear.

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Richmond, Va: Question about pruning a leggy Nandina...the plant has reached a height of about 5-6' with little foliage at the base of the plant. In order to reduce the height and encourage lower growth, approx. how many canes do I need to prune down and to what height? Planning on doing the pruning late Sep to early Oct.

Thanks.

Adrian Higgins: There is a school of thought that you shouldn't prune then because you will induce fresh growth that will be damaged by frost. My feeling is that this problem is overstated and that late season pruning isn't that harmful. With nandina, you can cut it back a little or a lot. You can even cut the stems back to the ground and new ones will emerge in the spring. The trade off in pruning now is in the loss of fall berries.

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Springfield, Va: Adrian, We are developing a landscape plan and want to plant a single evergreen tree near the corner of the garage to act as a screen, but also to be decorative and pleasing year-round (no yellowing or turning brown). Location will be in full sun. Any suggestions? Thank you.

PS: You're great on Washington Post radio.

Adrian Higgins: Thanks for the kind words. Depends on the height. I think if you need a large evergreen, the arborvitae Green Giant is a good choice. If you want one that will get to 12 feet instead of 25, I think the Hinoki falsecypress is a good choice. There are some sweet hollies out there too, though they need a partner to set berries.

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Washington DC: I am thinking about growing flowers for a wedding rather than buying them. Could you recommend a few types that are relatively reliable producers, produce flowers between April and the end of June, and can be grown in a community garden plot? Many thanks.

Adrian Higgins: Larkspur and bread poppies, sown in the fall, irises, salvia May Night, and roses, of course.

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Washington DC: Hi! I am looking for attractive dwarf evergreen shrubs for a sunny location (not broad leafed evergreens-I already have enough of those)--do you have any recommendations? Also, is euphorbia hard to grow? I have tried a couple of spots in my garden without luck--what does euphorbia need to thrive? Thanks so much for your advice!

Adrian Higgins: I would go to the dwarf conifer collection at the National Areboretum and see what takes your fancy. Recognise that the specimens there are mature and bigger than most garden examples. I like Japanese garden juniper and shore juniper, as well as dwarf Hinoki false cypress and some of the lower growing false cypresses.

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Fairfax, Va: Hi Adrian. I have what I believe are siberian irises (I've never seen them bloom, so I'm guessing) growing in very poor clay soil in my backyard. I'd like to move them to a more hospitable area. What conditions do you recommend?

Adrian Higgins: They actually do all right in heavy clay soil, they love moisture, especially in the growing season and will grow high and flower abundantly in a moist site. Now is a great time to divide and move them.

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Bethesda, Md: We have a section of our yard where water pools up in rainstorms and gets partial sun/shade. We've started building it up with topsoil in preparation for planting. Could you recommend some flowers, small shrubs, non-flowering plants that would do well in these conditions? thanks.

Adrian Higgins: Make sure it stays reasonably moist in periods of drought. There's nothing worse than moist loving plants in dry shade. Be careful that the topsoil you're bringing in is not clay subsoil. Squeeze it in the palm of your hand, if it turns into a puttylike ball, you should move on to something else. Organic matter would be better. I would try ferns, hostas, hardy begonias, Siberian and Japanese irises, creeping jenny, hydrangeas, ligustrum, monarda, carex, clethra.

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Severna Park, Md: Hi Adrian - I read your nandina response with much interest - I always want to prune in early fall, but put it off til November because I had always heard the plants could be damaged. Does your advice apply to shrubs other than nandina?

Adrian Higgins: Pretty much, I have found that certain plants don't know when to shut down, roses and crape myrtles, for example, and that you should probably not tackle those. Be aware too that if you're pruning anything that flowers in the spring, you will be removing next year's flower buds.

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Hillsboro, Va: For weed prevention, I use newspaper then mulch. If I plant bulbs and place newspaper over the planted area, will the bulbs be able to grow through the newspaper in the Spring?

Adrian Higgins: IN theory yes, supposing you don't have lots of sheets and it is wet. But bulbs need to be planted as deeply as seven inches, so it's no use putting a tulip bulb down three inches on top of a newspaper. This would be the squirrel equivalent of fish and chips.

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Capitol Hil, Washington, DCl: Hi. I have a pink guara. It's gotten rather large after the last two years. I love all the blooms and it's reblooming. I'm wondering if I should have been cutting it back/dead heading during the year. Would it have rebloom more? Also, can I divide it? It's using up a lot of space.

Adrian Higgins: Lucky you. Gauras have a nasty habit of going away after a winter or two, so I would savor your success. I have never had any live long enough for dividing to be an issue, they don't seem to produce offsets quickly. It is one of those rare perennials where deadheading seems unnecessary to prolong the flowering. I would just enjoy it. If it is too big, you might want to move it, but do so now and be gentle with the root system.

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Alexandria, Va: Hi Adrian,

I bought two dwarf alberta spruce in May and potted them on my semi-shady patio. One has almost completely turned brown and dropped a lot of needles. The other has a few brown patches, but not nearly as damaged. Any idea on what damaged the one? Can it be saved or should I replace it?

Thanks!

Adrian Higgins: These plants are magnets for mites. This was a horrendous year for mites, which like it hot and dry. I would only grow one of these if I could keep it in partial shade and hose it regularly, maybe twice a week, to keep the mites off.

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McLean, Va: I just purchased a bag of tulips bulbs and I was wondering when should I plant them? Thanks!

Adrian Higgins: Tulips don't initiate growth until soil temperatures drop below 50 degrees, probably in November. You could plant them now in a well drained bed. If you are storing them, I would make sure they are in a well ventilated room to prevent rot. The crisper of your fridge is actually an excellent place to keep them (definitely not the freezer).

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Germantown, Md: Hello Adrian,

I purchased some summer flowering bulbs (they were on clearance) a few months ago, but have not planted them yet. The bulbs include peonies, liatris, and asiatic lilies. Can I plant them in pots now and overwinter them inside, maybe in my basement?

Adrian Higgins: If they are still alive, a big if probably, they need to go into your garden now. These are all hardy plants that don't want to be inside in the winter.

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Arlington, Va: Mr. Higgins, Thank you for having these chats. I hope that we will be able to have them in the winter like we did last year. I ordered some trillium grandiflorum that are scheduled to arrive next week. Do you have any advice that will help improve my chance of success with them? Thank you!

Adrian Higgins: I think this will only extend well into the winter as long as people keep asking questions. Gardening, of course, is a year round endeavor and planning and planting and pruning and soil preparation continue throught the cold months. I sometimes have a tough time convincing my colleagues of that. Give the trilliums what they get in nature, and they will seed and multiply over the years. (Ants move the seeds around). So, an open, moist woodland with lots of rich organic matter in the soil and as a mulch. They will not be happy in heavy, dry shade, nor will they in heavy soil or full sunlight.

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Burke, Va: Adrian, What is your opinion on Crytomeria for planting an evergreen accent near a house? I have seen two varieties: Yoshino and Sekkan-sugi, but unsure if one is superior to the other. Do you recommend any other type of evergreen tree for the Northern Virginia area.

Adrian Higgins: Cryptomeria are at about their southern limit here. Yoshino is a great variety, I have it, but I don't know the other. They need a site in full sun or partial shade and prefer a location where they will get some protection from winter wind (from the northwest). Mine have flourished on a site that actually stays a little moist. They can get a serious mite problem late in the season if it is dry from now to Thanksgiving. Generally, though, they are fantastic large conifers that need room.

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Princeton, NJ: So I finally found out that the reason my hydrangeas aren't blooming (planted 2+ years ago) is that when the deer ate them all the way down to 3 inch stems in early spring, they had eaten the flowering buds off. I am planning on pruning the bushes, which I hadn't done before, but don't know how far down to go. Also, I read that adding Miracid to the soil will help them bloom in the spring. Will covering them with netting to keep the deer away prevent the plants' growth? Thank you.

Adrian Higgins: I think you need to exclude the deer in some fashion before you address the hydrangeas. Isn't it curious that Einstein, a Princeton guy, unlocked the secret of the universe but couldn't figure out how to get rid of deer? Why do you want to prune the hydrangea? People do this and remove the flowering buds for the following season. You only need to take pruners to hydrangea when the shrubs has become congested after several years, and then you take out maybe a quarter of all the canes without removing the remaining flower buds. The problem with netting is that it will have to be adjusted in the spring as the new stems grow. I think fencing is in order.

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Great Falls, Va: Hi Dr. Higgins, thanks for taking my question. Can we grow allium here? I especially love the giants. If so, when is the right time to plant the bulbs?

Adrian Higgins: Lots of allium choices, including the really big ones like giganteum and Schubertii. They do well here though they do not persist as much as I would like, in my garden at least. You may have better luck with them.

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Charlottesville, Va: My Russian sage has really taken to the rain, warm days and cool nights and has gone on a growing spree, stretching into the air and sending off underground shoots. When is a good time to trim it back, and how do I do it? Thanks.

Adrian Higgins: You can trim any wayward branch at any time. I cut mine back when they grow over a path, for example, but I don't cut them back hard until late winter. You would want to treat it like a rose bush and cut it to about 12 to 18 inches.

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Crofton, Md: I have two questions on how to fix some problems that the weird summer left me.

1. My grape hyacinths are coming up again! This freaks me out. What should I do, and will they come up in the spring like normal?

2. My boxwood appears to have suffered some damage from the heat/dryness. One side of it has some extensive burned up limbs. There is some new growth on it in parts. What to do?

Thanks so much for your advice!

Adrian Higgins: Grape hyacinths grow leaves in the fall, which overwinter, and then bloom in March and April. I know some gardeners who trim back the leaves and claim that it doesn't effect flowering, but I wouldn't do it.

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Norwood, NY: My mother recommends waiting until after the first fall frost before picking winter squash. She says it improves the flavor -- do you agree? How can you tell when squash is ready to pick?

Adrian Higgins: Your first frost is about a month before ours, so that maybe fine. I wouldn't leave ripe fruit here for a month in the garden. Nick it with your thumbnail, if the rind doesn't yield, it's ripe.

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Alexandria, Va: Hello there!! My grandmother who lives in the area has a thriving raspberry bush in her side yard. I'd like to start a "child" plant of my own, what is the best way to do this? Take a cutting and put it in water? Plant some of the berries? I'm an extreme novice and live in an apartment, so we're talking a pot on the porch until it gets really big.

Adrian Higgins: Raspberries spread through suckers, and you can simply dig a rooted sucker from the edge of the patch. However, raspberries can get sickly with mosaic virus in just a few years, and if your grandmother's are yellow and stunted, I would buy a fresh, virus free plant of your own.

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Orange, Va.: I heard you on the raido discussing banana trees the first Sat in May. I was lucky to find a hardy one and a red one. I would like to know how I can keep the red one till next spring. Do I cut cut the plant back. I do have a small greenhouse but with the size it would take up a lot of space.

Adrian Higgins: If you've got a greenhouse, what could be nicer than a banana tree in the winter? Otherwise, dig it after the first frost, remove the top growth, and put it in a pot and bring it indoors in a cool, barely heated space, and plant it out again in the spring when the soil has warmed.

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Silver Spring, Md: Thanks for doing these chats! We have several good-size tomatoes on our Brandywine, abundant tomatoes on the Green Zebra, and a few small ones on the Better Boy. With this cool weather they aren't really ripening, and the GZ in particular tends to split with all this rain. What should we do with them? Leave them on until frost is predicted? Would fertilizer help them ripen? Or take them off and try to ripen, or enjoy some fried green tomatoes?

Adrian Higgins: I would keep them on the vine until they show the very first signs of ripening and then bring them indoors.

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McLean, Va: Adrian, Is the Hinoki Cypress a good choice for an evergreen that will be located in full sun and located as a focal point near the house?

Adrian Higgins: Some authorities believe it better with a little afternoon shade in our region.

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Corolla, NC: What sort of plants, bushes, and small trees would you suggest for sandy soil ?

Adrian Higgins: I would buy a book on seashore gardening. Alas, our time has come to a close. See you here again next week.

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