Adrian Higgins on bee hotels and all things gardening.

By Adrian Higgins/The Washington Post
Jun 25, 2020

Washington Post gardening columnist Adrian Higgins took questions on gardening.

Thank you for your column on bee houses. We have two houses and they are filled every year with mason bees. All of the articles on mason bees or other tube using bees never really talk about when the larvae hatch and emerge. Can you please discuss - after the tubes are filled when do the bees emerge? All of our tubes are filled by Middle spring. When do I replace the tubes? Do I wait till all or most look empty indicating the larvae have hatched and the new bee has emerged? When does that occur? Thank you for your help.

Hello, and greetings to all. I wrote this week about bee houses, how to make them, how not to make them, and how to optimize their use by small solitary bees. One tube can house several larvae -- the parent bee compartmentalizes with a mud wall. The larvae pupate later in the year and overwinter as cocoons before emerging as adult bees in the spring. 

Greetings, gardening friends. Producer here with a link to Adrian's most recent story, about bee houses.  Also check out his stories about  New York's High Line,  how author David Culp is finding solace in his garden during the quarantine, how the sudden heat and humidity of a Mid-Atlantic summer affects the garden and more.

The previous owner of my house planted a lawn full of zoysia grass, which is fine in the summer but looks horrible throughout the winter, so two summers ago I decided to remove the lawn and turn it into garden space. I've been planting but I'm in a constant battle with weeds and crabgrass. I have pets who go on the lawn so I don't want to use chemicals, but I also don't want to spend six hours every weekend weeding. Any suggestions?

I'm not sure what a garden space is. If you have replaced the lawn with plant beds -- hooray -- the key to success against weeds is to plant intensively enough to crowd them out. Most folks don't plant densely enough, no doubt because full sized ground cover and perennial plants are expensive, and planting dozens of them becomes costly. I always advise to find the smallest plant you can -- some places sell plugs -- space them correctly, and allow them to fill in, which they will do in a year or two. During this establishment period, you must weed. If you weed often enough, you will stay on top of it. That means at least once a week. If you wait a month between weedings, you're doomed. 

Where in NOVA can we get assistance in establishing more native fauna and flora in our ten acres of meadow in the Shenandoah Valley?

I would think the Potowmack Chapter of the Virginia Native Plant Society would be a good place to start.

Larry Weaner is an acknowledged expert on meadow design on the East Coast.  He has a book on the subject you might want to get.   This is column I wrote about Larry some time ago:

Can winterberry shrubs tolerate water logged soil?

Yes, Ilex verticillata is native to marshy areas and will grow in wet soil, (and less wet soil). 

My cucumbers are quite happy and taking over the rest of my garden. They've already taken over the peppers and are starting on the tomatoes. I've given them their own tomato cages in an attempt to stop the spread but it was a fleeting victory. How do I get them to stay put and start focusing on growing actual cucumbers?

What a nice problem to have. As long as you haven't gone wild with the nitrogen fertilizer, they are doing what they should: Putting out a lot of top growth before setting flowers and fruit. Perhaps you have planted them too close to the other plants and getting them to ascend some structures seems to be a good approach. Be patient, and be vigilant against the cucumber beetle. Pick them off as they arrive and dispose of them as you prefer.   It's not too late to sow fresh seed elsewhere. 

I planted some lavender a while back. People told me it's hard to grow but my yard loves it! I was thinking about cutting off the flowers and drying them, but the bees have been loving it so I'm letting them go to town. Bonus is they are enjoying the flowers on the nearby hyssop, nandina, and jasmine as well. I guess the lavender attracted them to my garden in general because I've never had so much buzzing out there. Go bees!

Wonderful. As soon as the flowers begin to fade, I would cut them off at the base of their stalks. This will keep the plants vigorous and promote a little reblooming in late summer. 

Rookie question: How do you harvest and cut back basil? Mine grow much more quickly than I use them and they end up really tall and flowering at the top. Should I be taking the leaves from the top? I usually take the lower ones so they don't get tough. Thanks!

No, you should pinch or cut the leaves from the top -- several sets of leaves down a few inches , this will promote bushiness and help to delay flowering, which degrades the flavor.

We are in NH and what time of year is best to add a "hotel"? We are particularly interested in pollinating our apple and peach trees next spring. Should we add a hotel now? Does it matter whether we buy leaf-cutter or mason bees?

Mason bees, or specifically one named the orchard mason bee, is an effective apple pollinator, but its life cycle begins early in the year. There is no harm in setting out nesting tubes now. You can buy these bees but experts tell me it's not necessary -- the bees are out there and will arrive if you create your bee house. 

Hello Mr. Higgins and happy summer to you! I have a volunteer passion fruit vine (no idea where it came from) growing in one of my garden beds. It is flowering a little bit do you have any suggestions for how to get it to put in more flowers? It’s very large (more than 6 ft already) and I’m hoping to get some fruit from it. Thank you, as always, for your helpful guidance.

This I assume is the hardy maypop, it may take a couple of years (or more) to put out a good flower display,  and fruiting depends on a long growing season (not sure where you are). I would do what I do for clematis and other vines when young, train them early where you want them to go, and cut them back as necessary to keep them in bounds. 

I noticed that this morning you mentioned you grow chervil. How? Ours always bakes and dies!

I don't grow it in the summer. I will sow it in September and it will grow happily through the fall and, with some protection, through the winter. It then flowers in spring and you can harvest the seed.  

First, thank you for article on bee hotels. I just checked my garden and really noticed the little mason bees for the first time (usually, I'm looking at the bumbles). I appreciate the knowledge. Wood sorrel, the kind with little yellow flowers and clover like leaves, has moved into my yard and I admit I like it. Is there any downside to just letting it have it's way?

The downside is that it is invasive and left unchecked will spread exponentially. The easiest way to weed it is to wait until the ground is moist and then uproot the entire plant with a firm but measured pull. 

We have a full-grown river birch with a large root that stretches across our backyard lawn. The grass is going to be dug up as part of a garden renovation. I don't want to kill the tree! Should any precautions be taken?

Any time you do physical damage to shallow roots, or compact the root zone with feet and, especially, equipment, you are compromising the tree. Before you start work, you should fence off an area around the tree, to the drip line, at least. If the root stretches farther out, and you value the tree, you might want to get some advice from an arborist before starting work, for ways to protect it. I'd give it a good watering first. 

I have an oak tree sapling which has been growing in a pot for several years. The main trunk is only about 0.5 inch in diameter while the tree is about 5 feet tall. Two or three years ago, I noticed a large gall develop on the trunk, about 2 feet up and at least 1.5 inch in diameter. The tree kept growing and the next year, the wasps or whatever larvae had been growing in there exited, as shown by the tiny holes they left all around the gall. The gall is still there, and the tree (a white oak I think) is still growing and looks quite healthy. My question is, should I do something about this or just treat it with benign neglect? I suppose the trunk will eventually grow around and swallow the gall. Will this have an effect on the long term health of the tree?

Wasp galls can be unsightly but don't really harm the tree. The bigger issue with a white oak is that it needs to get its roots down deep, and the sooner you can coax it out of the pot and into the soil, the better. Though I would wait until late summer to do this, if you have a place for it. 

I love it and have tried to grow it numerous times, in containers and in the ground, but it starts flowering pretty much immediately. What am I doing wrong??

In hot, humid climates like ours, cilantro is like chervil and arugula: something to grow from late summer on. The seeds soon germinate in warm September soil and the foliage grows merrily as the days get cooler. 

We don't have a garden but do have a porch and just got a new blueberry bush. How big of a pot or container does it need?

I have found blueberries to be much harder to grow as long lived shrubs than other native shrubs and growing them in containers puts additional stresses on them. I would turn to southern highbush types in the Mid-Atlantic. This doesn't answer your question. I would grow yours in a pot at least 18 inches in diameter, and in an ericaceous soil mix. Blueberries are shallow rooted and need continual even moisture -- but not waterlogged soil. You will need to check the soil moisture conditions every few days. This is a column I wrote about blueberries:

I like ferns. What kind of varieties can I incorporate into a mid-Atlantic garden and what kind of conditions do they need to succeed?

There are many lovely hardy species of ferns, most native and some that will take drier conditions than others, though they thrive in the dappled shade of hardwoods. Your choice will depend on the size and nature of your site. The American Fern Society site may help:



This is technically not a gardening question, though it sort of is because it’s nearly impossible to enjoy a garden with mosquitoes. What do you find to be the most effective way to eliminate/reduce mosquitoes – mosquito coils, mosquito magnets, citronella, marigolds, etc.?

Thank you for this important question, which has to be our last today. This is the key moment in the season to get on top of mosquitoes. I heartily dislike the practice of getting your yard sprayed for them because it doesn't provide a permanent solution and it kills beneficial insects. You need to get rid of all sources of standing water and ask your neighbors to do the same. I use repellent and I use citronella candles, which seem to help a lot. I also wear cotton and linen clothing that covers my limbs. I spray my hat with repellent, though not while I am in it. Thank you for joining me today, and please take the opportunity of staying at home to get your teeth into those garden projects you've been putting off. 

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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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