Author: Erica

The Need to Weed

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I recently got back from a 10-day trip away from home, and had to brace myself before I approached my community garden plot. I hoped there wouldn’t be pests or diseases to deal with. I was pretty sure the tomatoes would have escaped the bounds of their cages. But the one thing I knew I’d encounter was WEEDS.

A close up of various weeds in a garden setting where you can see some leaves of corn poking through.
Weeds including wood sorrel and unwanted grasses in a bed growing corn and onions.
Large okra leaves in a raised bed with various weeds underneath them.
SO MANY WEEDS in the okra bed at the Derwood Demo Garden

It was not as bad as I’d feared, but I still had to deal with a lot of unwanted plants, which is basically what weeds are. All plants have their place, but that often isn’t in our vegetable gardens, flower beds, or landscapes. I often hear from people that we should let certain weeds grow, because they are part of the ecosystem, because they support pollinators, or because they have other uses, such as being edible. In some very specific cases, these are good arguments. If I have a native plant come up in the middle of a veggie bed, I might let it grow, or more likely I would transplant it to another location in my yard (or into the row of native flowering plants I’ve established in my community garden plot). If it’s a non-native invasive that is about to produce around a thousand seeds that will spread the plant all over my yard or the community garden, I’m going to yank it, even if it has pretty flowers that the bees like. I might also let an edible weed like purslane grow, if I’m in the mood to harvest it and use it, but I’d try to contain it before it spreads too far.

Here are the main reasons that you should remove weeds from your vegetable garden, even if it’s a lot of work and you don’t feel like it:

  • Competition. In some environments, growing lots of plants close together is beneficial. Even vegetable gardens can benefit from close planting in some circumstances, to shade the soil or to confuse herbaceous insects. But weeds are weeds because they are survivors, and they tend toward domination. They will swallow up your desirable plants in no time, suck up all the water and nutrients, and provide you with nothing.
  • Reproduction. Weeds spread like crazy either via seed or by suckering roots. If you have one weed this year, next year you will have hundreds. This is bad enough in your own backyard, but if you have close neighbors, or if you’re in a community garden, you are not going to be popular. (In a community garden, you may be ousted before next year, depending on the rules and how they’re enforced.)
  • Pests and diseases. Each weed is part of a particular plant family, often the same family as some vegetable you’re trying to grow. It may harbor some of the same pests and diseases as that vegetable. Guess which plant is going to shake off the problems faster, and which one will tenderly succumb?
  • Ticks. Love to hide in weed patches and hitch a ride as you pass through on your way to the squash. There might also be other critters lurking in out-of-control weed jungles, such as snakes (good to have around, but startling), or entire rabbit families in a nest. Just to name a few. Plant a native hedgerow and let them live there, not in your tomato bed.
  • Aesthetics. I put this last for a reason, but even if you personally don’t long for a tidy garden, keep in mind that vegetable gardening as a pursuit sometimes gets bad-mouthed for being “messy” and any actually messy gardens can contribute to a stereotype. HOAs that forbid front yard veggies, neighbors that complain about completely hypothetical rats, they all learned their prejudices somewhere. Don’t let it be your garden. We all want more homegrown produce in the world, not less.

So get out there and pull the weeds! And then, think about how to stop them from growing in the first place. Here are some things you can do this summer and beyond:

  • Mulch. Put something over your soil, preferably an organic mulch like shredded leaves, straw, or dried grass clippings. You can even use weeds as mulch if they don’t have seeds on them. Compost can be a mulch if you are sure it’s been heated enough to kill weed seeds. Synthetic mulches like black plastic or weed barrier fabric are also an alternative, though they won’t add organic matter to your soil. When you disturb the soil to put in plants or seeds, try to cover it again to prevent the germination of weed seeds that have been brought to the surface. (Obviously, don’t put a thick layer of mulch over the seeds you just planted.) Mulch is also great at keeping the soil from losing moisture in the heat, and maintaining it at an even temperature. And it may help prevent fungal spores from splashing up from the soil onto your plants.
  • Learn to ID weeds. Know your enemy! As you pull a weed, use a plant ID app or other source to identify it. After some time and work, you’ll know the common ones and you can learn about how and when they reproduce. Do I have to get the whole root out (yes, for perennials) or can I just remove the top of the plant before it goes to seed (usually, for annuals)? How early in the year do I have to get out there to start pulling weeds? (Earlier than you think, alas.) The other advantage to knowing weeds is that you’re less likely to mistake them for the plants you want to grow, and vice versa. Close observation works equally well for identifying veggie seedlings. Be an informed gardener!
  • Think about growing in containers. Refreshing the potting mix every year will definitely mean fewer weeds.
  • Speaking of which… think about containing or restricting plants that are desirable but act like weeds. Various mints and their relatives, shiso/perilla, leaf fennel, some amaranths… I have personal knowledge of how badly these spread, and I’m sure every gardener has a similar list. Whether you trap the roots in a pot (on a paved surface, in the case of mints) or make very sure to cut off the tops before the seeds go flying, it’s a responsible thing to do and will spare you a big surprise come the next growing season.

And lastly, be patient. Weed seeds lurk in the soil for many years, so they probably will keep coming back. There will be setbacks. But eventually, things will get easier and more enjoyable, and (mostly) weed-free.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Dealing with Pest Issues in Container Vegetable Gardening

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Close up of a gey squirrel eating potted plant sitting ontop of a brick wall.
Wildlife can be cute, but also destructive! Photo via Adobe Stock

You’re happily growing lettuce in a salad table, watching the little seedlings get bigger, and then one day half of them have been dug up and tossed aside. Or you’re about to harvest your kale and then realize it’s full of holes and little green caterpillars. Or your eggplant leaves are suddenly nothing but lace. Maybe someone is stealing your tomatoes, or—more insultingly—taking a bite out of each of them. Or maybe everything is just… GONE.

Pest issues are not unique to container gardening, of course—all veggie gardeners deal with them. But just as containers have their pluses and minuses in every aspect of food growing, they sometimes provide specific challenges and benefits when it comes to dealing with pests – whether insect or animal.

By the way—let’s acknowledge here that the creatures we’re talking about are just trying to get along and feed themselves. They don’t know that they’re putting us to extra trouble (even if it really seems like squirrels in particular are just trolling us). It would be great if we could jall just get along without harming each other. So the proposed solutions below don’t go as far as hurting or killing anything (if you want to use pesticides against insects, that is up to you, though please be sure to carefully follow the label instructions). These methods all follow four principles: Location, Exclusion, Deterrence, and Distraction.

PART ONE: INSECTS

Here’s a typical scenario from Home and Garden Information Center’s Emily Clark-Waterson:

I planted kale in a flower box in the spring in a new self-watering flower box container, hanging off my balcony railing. It grew beautifully and I was able to clip young leaves and let them keep growing until the summer weather got too hot. I planted it again in late August for a fall harvest, except this time I started to notice some leaf damage and found a type of Imported Cabbageworm. These moved fast and left little to be harvested. They like to hide along the midribs. Lesson learned: Always cover your brassicas with insect netting or floating row cover to help prevent this. A small piece of tulle from a craft store works well, or you can purchase various-sized mesh bags to put over containers. I won’t be making that mistake again.

Kale leaves with large holes and small green caterpillars resting on the leaves
How many cabbageworms can you find? Photo: Emily Clark-Waterson
A small green caterpillar on the underside of a kale leaf.
They really can be camouflaged in the leaves. Photo: Emily Clark-Waterson
A larger green caterpillar rests along the midrib of a kale leaf with large holes in it.
This one has eaten well! Photo: Emily Clark-Waterson
Two containers with vegetable plants sit along a white picket fence. Each container we had a tomato cage and piece of tulle draped over it
Prepared for pests this year with tomato cages and tulle held together with clothes pins. Photo Emily Clark-Waterson

This is a great example of Exclusion. In fact, covering plants with materials like this solves the majority of insect problems—and it’s so much easier and cheaper in a container than covering a long row in an in-ground vegetable garden. Here are some other examples of plants in the brassica family being covered to protect them:

Fine mesh instect netting stretched over plsatic hoops that are over a container of greens.
Insect mesh and hoops over Asian greens. Photo: Lily Bruch
a container on the edge of a raised bed garden with a sheer cloth covering some greens growing. The cloth is draped over and tied around the conatiner with a black string.
Floating row cover over brassica plants keeps caterpillars and other pests away. Photo: Robin Ritterhoff

Plant covers work against other insects as well, for example, to keep flea beetles off of eggplants. But in this case, growing in containers provides another advantage, one of Location. Erica Smith has had success over the years by growing eggplant in containers on her deck, which keeps them well away from the flea beetles in the soil below. MG Robin Ritterhoff also uses this method, making sure to replace at least the top third of the potting soil every year in case beetles are lurking. But MG Lily Bruch says her eggplants still get eaten despite growing on a deck, so she uses row cover and also plants marigolds in hopes of Deterrence. Sometimes strong-scented plants either confuse or annoy insects and keep them away from your vegetables. It’s worth trying, since flowers also bring in much-wanted pollinators and other beneficial insects.

And what if the insect eating your plant is actually beneficial? MG Mary Anne Normile writes:

[It’s a tough call] when Eastern black swallowtail caterpillars feed on container parsley. I love the butterflies, but the caterpillars can denude a parsley plant in short order. No good solution unless you have another desirable (to the caterpillars) plant to relocate them to, except possibly to have a fresh batch of parsley seedlings on hand to plant for the short period after the caterpillars stop feeding and the end of the growing season.

If you have room, you can plant extra herbs in the parsley family, such as dill and fennel, which the swallowtail caterpillars will also enjoy. (Also make sure to have lots of nectar-producing flowers for the adult butterflies.) You could also cover up a few of the parsley plants to keep them just for you.

When pest problems arise in container plants, make sure you address them quickly, because it’s easy to lose your entire crop in very little time.

PART TWO: ANIMALS

(Yes, insects are animals; let’s not be pedantic.)

Erica here:

This is a photo of the gate to my old vegetable garden:

A half eaten tomator sits ontop of a wooden railing of a gate.

This is a typical squirrel move. Didn’t even eat the whole tomato and left it in an obvious place just to taunt me. Photo: Erica Smith

And this year, I have a squirrel who loves Swiss chard:

Squirrel seen through a window screen sitting on the edge of a planter on a deck eating lettuce.
It ate every single seedling out of the deck planter, leaving the lettuce alone, and then climbed into my garden and snacked on the beet leaves. Oh well, no Beta vulgaris for me this year! Photo: Erica Smith

Mary Anne writes:

I have had squirrels … dig up freshly planted basil in containers. They seem to love fresh soil. They don’t eat the basil, they just dig up the plants and sometimes toss them out of the container. I replant them and sprinkle the surface of the soil liberally with cayenne (the cheapest stuff, not Penzey’s), repeated after a rain, and that deters them. Once the basil plants are large enough, the squirrels don’t bother them.

Squirrels do instinctively dig in fresh soil, sometimes burying nuts, but other times looking for food or following up an interesting smell. Lily reports that they dig up her lettuce seedlings; her solution is to cover the container with a metal grid or chicken wire.

Planter box on a deck with lettuce plants growing in it. Metal chicken wire is formed over the top.
Chicken wire to exclude squirrels Photo: Lily Bruch
Salad greens grow up through wire mesh in a planter box on a deck.
Metal wire grid to exclude digging squirrels Photo: Lily Bruch
A white flower box with salad greens sits on the edge of a flagstone path. A pink netting food tents resting rests on top of the container blocking wildlife from digging.
Picnic food tents resting over a container is enough to keep the squirrels from digging up new lettuce seedlings. Photo: Emily Clark- Waterson

Lest you think this section of the blog is all about squirrels, they are, in fact, one of the worst pests for container gardeners (and veggie gardeners in general). They can climb anything, and they eat a wide variety of foods. And they are determined. They may be the hardest animal to stop once they start bothering your garden. Except possibly for raccoons—and former MG Nancy Moses had both of them!

Here’s Nancy describing the year she planted vegetables in containers on her second-story deck—in a yard surrounded by a six-foot fence but that backs up to woods.

The squirrels and raccoons climbed over our chain link fence, up the 13 steps to the deck, taking over the territory as their own.  The resulting poop was unpleasant!  The light-weight, conniving, hungry squirrels politely climbed over the netting held up with metal stakes in each tomato-growing pot; and the raccoons knocked over the pots and anything else in their way toward achieving their goal of mass destruction and hunger gratification. 

Nancy says that after that, “You could say that I quit; but I view it now as having just politely surrendered.” And honestly, how can you blame her? She tried the principles of Location—putting the pots up on a high deck—and Exclusion. Maybe the netting could have covered the plants more thoroughly, but the raccoons still would have knocked the pots over. The only real solution would have been Total Exclusion, meaning a fence that completely surrounded and covered the pots, which does not lead to enjoyment of the deck by humans.

So back to those principles. Location often works (in less extreme circumstances) by keeping plants in pots up high where some animals won’t venture. Most deer (we can never say all) won’t climb up steps and some won’t even venture close to a human home. Rabbits are short and don’t climb, so higher planters are unreachable. A balcony location keeps even groundhogs off, though probably not squirrels and certainly not birds.

Exclusion with row cover or netting can keep some less determined animals and birds away. Fences are another solution—you can fence off part of a deck or patio, or put your containers inside a fence in the yard (or use them as part of your regular veggie garden). Again, if you have serious squirrel, raccoon, or bird issues, only a garden enclosure with a roof will help.

Deterrence can mean using strong-scented plants to warn away animals that don’t enjoy those smells. It’s no guarantee, but maybe will stop the casual visitor.

Colorful wooden planters stacked agains an outside side to a building with herbs, annuals, and strawberries.
Colorful planters hold strawberry plants up high, and a “citronella plant” scented geranium as one of the strongly-scented deterrent plants to offend visiting herbivores. Photo: Erica Smith

In extreme cases, you can revert to growing only these sorts of plants. Herbs like rosemary and thyme, onions and their relatives, and hot peppers may be unattractive to animals.

There are other methods of deterrence if you want to try automatic water sprayers, constant noise, or bird scarers of various types. Avoid sprays that are meant to repel deer if they contain any ingredients you wouldn’t want to consume.

Distraction means giving our animal friends something else to think about. Some garden writers advise providing an alternate source of food, such as edible plants closer to the animal’s habitat, but be wary of bringing in an entire extended family that will reach your closer-to-home plants eventually. Also, be sure to keep compost containers secure if they hold food scraps, and keep fallen produce cleaned up. (We have not talked about rats so far in this post, and let’s not start now.) But do make sure animals and birds have a water source they can visit—sometimes they are eating your vegetables because they’re thirsty.

If possible, try to provide natural sources of food by planting shrubs and trees (preferably native to your region) that grow seeds, nuts and fruits. If you don’t have room yourself, use our resources to learn about native plants and try to convince neighbors or anyone else who controls plantings in your neighborhood to grow them.

Dealing with pests can be challenging, but it feels great when you rise to the challenge! Growing in containers can sometimes help you combat pests, such as when you can easily cover a pot or place it somewhere the pests can’t get to. And if you need to take a season off to regroup, it’s so much simpler to just empty the pots and put them away, rather than having to close down a big garden. Do some research, find some solutions, and come back refreshed to try again!

Share your struggles and triumphs in the comments—and best wishes!!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Check the Temperature Before You Plant!!

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Several trays of pepper seedlings in quart-size pots sit on a deck getting used to outdoor temperatures.
Pepper plants hardening off

A short post today, in which I make my annual plea to hold off on planting summer vegetables until it’s warm enough. Please – your garden will thank you later!

We have some guidelines on the HGIC website about when to plant vegetables and how to harden them off (get them used to outdoor conditions). Remember, though, that planting isn’t about dates; it’s about temperature. It is not a hard-and-fast rule that your tomatoes should be in the ground by Mother’s Day. What if it’s 40 degrees on Mother’s Day? Bad for outdoor brunch, but also bad for young tomato seedlings.

The round temperature dial of a compost thermometer registering about 55 degrees Fahrenheit.
A compost thermometer is useful for checking soil temps

In general, vegetables that prefer summer’s heat also don’t like spring’s cold. Tomatoes, peppers, squash, cucumbers, and all their friends want soil temperatures over 60F and air temperatures over 50F (including at night). Try to wait to put them in the ground until the forecast shows at least a week of these conditions, with no cold snaps or heat blasts. Of course, spring is full of crazy ups-and-downs (especially this spring) but if you can give the plants a good start, they will tolerate temperature swings better. If a frost is predicted, or really anything below about 45, throw some kind of covering over the plants: heavy-duty row cover if you have it, but a sheet or light blanket will do.

Get to know your garden’s microclimate – if it’s protected from strong winds, plants will tolerate cold better; if it gets a bit of afternoon shade, they will get through high heat with less damage.

You can purchase all kinds of devices to give your plants extra protection, but after trying them all I found I preferred just having some patience. If you do use them, make sure they’re easy to put up and take down – struggling with a complicated shelter in wind and rain is no fun, nor is removing the whole thing again when it’s 85 the day after dropping to 39.

I know, all my plants are huge too, and really want to go outside. But I’m going to wait until it’s time.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Spring Crops in Containers

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Lettuce and arugula seedlings growing in a terracotta-colored rectangular planter
Salad greens like lettuce and arugula are easy to grow in various sized containters Photo: Erica Smith

Maybe your first thought on starting a container vegetable garden was “I can grow tomatoes!” Which is great—but tomatoes are a summer crop and it’s not time to put them outside yet. You can start your garden even earlier, though, with spring plantings.

Here are a few of the spring crops you can grow in containers:

The only spring crops I would hesitate to grow in containers are large brassicas like cabbage, broccoli, and cauliflower, and even those could be planted in containers—it’s just that you would only plant one per pot, which might not be worth the effort, unless you have space for a lot of pots, no in-ground garden, and a real love of fresh-grown cabbage.

I’m also not a huge fan of potatoes in containers, because they don’t usually produce very much and it doesn’t seem worth the space and expense when potatoes are so cheap to buy. Nevertheless, I’m going to give it another try this year, just so I can report back here!

Here are some tips on planting spring crops in containers:

  • In some cases it may be more practical to start with transplants rather than planting from seed. This allows you to get the spacing just right and eliminates tedious thinning of extra seedlings. It’s also much faster. But seeding also works fine.
  • Consider the shape of the container when choosing a crop (or vice versa). Crops you want to harvest a lot of, like lettuce or radishes, will work better in a wider container. They also have shallow root systems, so the container doesn’t have to be very deep. Whereas if you’re going to grow carrots, make sure you have a container several inches deeper than the expected carrot length.
  • The usual container growing guidelines apply: use lightweight potting mix rather than real soil from the ground; water frequently; apply fertilizer as needed.

Here are some photos of spring crops growing in containers:

Pea plants in a black fabric grow bag with sticks for them to grow up
Chive plants in a rectangular container
Lettuce, arugula and chard in a raised planter with legs
Seedlings of lettuce and brassicas in a square white raised planter

Photo collage from left (click image to enlarge): peas in a fabric grow bag (a great inexpensive option for lots of crops); chives in a rectangular planter (herbs are wonderful container crops); lettuce, arugula and chard in a raised trough planter on my deck; various spring greens in a keyhole garden, which has an area in the middle meant for creating compost to feed the plants. Except for the trough planter, all of these are from the Special Projects area at the Derwood Demo Garden.

This does bring up a question: what counts as a container? The raised keyhole garden and raised trough planter in the photos are much larger than the typical pot or planter, and may be closer to a raised bed. There’s certainly a fuzzy line between the two types of gardening.

To my mind, a container is an object that holds growing medium more likely to be potting soil than real mineral soil from the ground, and that could sit on a deck, patio, or driveway rather than being situated in a typical vegetable garden layout. I definitely consider my trough planter to be a container, if a very large one. The keyhole garden is an edge case, maybe more of a raised bed the way we use it at the Derwood Demo Garden in Montgomery County, Maryland. But it could be a patio planter, so I’m happy to regard it as a container as well.

In any case, it’s time to get those spring crops growing if you haven’t already! Happy spring!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Related information:

Growing Vegetables in Containers and Salad Tables

A container gardening cautionary tale

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In my last post, I mentioned that it’s important to select the correct container size for growing vegetables. In fact, I pointed out that the correct size is nearly always bigger than you think it should be. I think the common error of putting plants in pots too small for them is akin to the instinct that makes us plant them too close together in in-ground gardens. They are just so cute and little when we put them into the ground—how can they possibly turn into hulking monsters with thirsty and enormous root systems? Don’t be fooled! Size up your containers and make your plants happy. (HGIC has a handy set of guidelines.)

It’s not just the size in gallons that matters to successful container selection, though, as my next-door neighbor found out last year. She grows tomato plants in pots on her sunny patio, and has great success. In fact I would say gargantuan success—her plants are huge!

A large tomato plant in a black container, being held up by a wire cage. Many immature green tomatoes are growing on the plant making it even more top heavy.
Photo taken July 22, 2017 – but huge even earlier!

I’m not sure what she does to make the tomatoes grow so tall so fast, while mine are still about half the size in my community garden plot. Soil in pots does tend to be warmer in late spring when the ground temperatures are cool, and my plants catch up over time. Potting soil with plenty of fertilizer included gives plants a fast start, and regular doses of fertilizer keep growth chugging along. Fertilizers with a high percentage of nitrogen produce rampant leaf growth, so that may be part of the equation, though the nutrients must balance out over time since her plants produce plenty of fruit.

In any case, it’s been working out well for her. Until last year. Last summer we had several periods of high winds. The top-heavy tomato plants kept crashing over. In July our neighbors went on vacation and asked us to water their plants, but on the first morning I went over and found the tomatoes on the ground. I ended up creating an arrangement of string, stakes, and cinderblocks to keep them upright.

Three large tomato plant in containers. Cinderblocks are gathered around the containers to help stabilize them. String and simple stakes (like those from a camping tent) are leading from the wire cage to ground to keep the plants upright.

So, container volume isn’t the only consideration—shape matters as well. Containers that are higher than they are wide may not work well with plants that get very tall. My neighbor (who was very grateful for the emergency tomato intervention!) had basically two choices: get new containers (wider, heavier, with a lower center of gravity, like half-barrels), or grow shorter tomato plants.

Therefore, I have introduced her to the Dwarf Tomato Project, and will be growing seedlings for my own use and hers. These dwarf plants, bred for growing in containers, produce tomatoes with real heirloom flavor, but they stay short (heights vary, but most are under four feet). I only have a little experience with these varieties (I figured the Year of Container Gardening was a good time to get more) but like heirloom plants, they’re inconsistent in how many tomatoes they produce over a season; some are prolific and some stingy. So we’ll see how it goes. I’m trying three varieties: Uluru Ochre (which I’ve grown before), Rosella Purple, and Summer Sweet Gold. I’ll also get some full-size plants to mix things up, of course!

The other advantage to dwarf tomato plants is that you don’t need huge containers, but still—I’ll go with the largest ones I own. Other vegetables that grow best in bigger-than-you-think pots include squash (and its relatives like cucumbers and melons), potatoes and sweet potatoes. Size up for success! Also, look at seed catalogs for varieties intended for containers; they will be shorter with smaller root systems and may still be quite prolific while demanding less water. (But remember to water frequently nonetheless.)

Spring is coming, so have your containers ready!!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

All photos by Erica Smith