Dear PoP – Roof top Garden?

Photo by PoPville flickr user Faucetini

“Dear PoP,

The warm weather has me thinking an awful lot about planting a vegetable garden. I live in an apartment with a rooftop deck and am thinking of trying a container garden. I’m wondering if your readers have any advice on where to get supplies. What plants grow well on a roof in DC? Any suggestions for tomato plants that won’t grow wildly out of hand? When’s the best time to start something like this?

Any advice would be helpful. My dad grew tomato plants in the yard when I a kid, but I have no idea what I’m doing now.”

Any roofdeck gardeners out there?

34 Comment

  • Well, any of the retailers (Home Depot, Ace, Garden District) will start carrying plants soon – Planting Date for MD (According to the Maryland Cooperative Extension) for tomatoes is May 1 – so I would think for DC it’s earlier than that – you are probably okay after mid-April…

    Make sure to use a deep planter so the soil is moist enough and doesn’t dry out… other plants that grow really well on DC decks are peppers and basil…

  • Oh, and if you are looking into starting the plants from seed, you should probably start that now… Southern Seed Exchange has seeds for veggies that can survive the hot and humid summers…

  • The planting date for Maryland, a state that DC is pretty much in the middle of, should be substantially different from DC?

    • Well, it’s always warmer in a city… DC is Zone 7b and MD is partly 7A/6B… so yes, there is a difference.

    • The average last frost date in DC is April 15th. Depending on where you are in MD, it could be later.

      If you put out tender plants and frost is predicted, a light cover (sheet or other light cloth) will protect them.

    • Clearly you’ve never been to San Fran.. Although an extreme example, if you drive 1 hour away from San Fran in any direction, it’s at least 20 degrees warmer in the summer.

      • The microclimates of the bay area are so different that average temperatures between the west and east side of SF are 10 degrees between the two. Different plants grow in climates just a few blocks from each other. In fact, it was Sunset Magazine that original came up with the zoned planting system as they needed a way to explain to East Coasters how different planting and landscaping was. The Sunset Garden books are wonderful and updated every year. They were my bible out there.

  • We’ve already had this discussion. I know, I know, you’d think that planting fruit and being self sufficient and all that is a good thing. You’d think that. But you’d be wrong. Eating plants that are grown locally is boring and repetitive. You’re thinking of delicious tomatoes, which are usually expensive in the stores, grown right in your own garden. You’re thinking personal satisfaction. Uh uh. Think again.

    The people of PoP (the PoPoP), have already spoken…

    • Drew:

      Chill out, brother.

      I saw the discussion on local growing and eating, but still wanted to ask the question, because I don’t like spending $10 on fresh herbs every time I make some tomato sauce. I’m not talking about trying to sustain an entire diet from local produce, or stopping my patronage of any restaurants that don’t serve all local foods. But tomatoes and fresh herbs on my roof, as well as having a hobby, are appealing to me. Sorry your life is so otherwise repetitive that eating anywhere aside from a restaurant is boring to you.

    • I disagree. Ain’t nothing in the world like home grown tomatoes.

    • Clearly, growing your own veggies is a great idea if you enjoy gardening, saving money and eating fresh produce

      I mean, “boring”? Really? You can’t come up with more than 1 way to prepare a tomato?

    • To each his own man. There is something really rewarding about cooking with ingredients that you planted and nurtured yourself. No one here is looking to grow all the food they need themselves, as nice as that would be in an ideal world, but to do something that is rewarding and calming. If its not your thing then thats cool, but understand that some people find it anything but ‘boring’.

  • Common Good City Farm has weekend classes on container gardening that your reader might be interested in taking.

  • We planted tomatoes in our back yard and had to give them away we had so many. We also planted four varieties, all of which would not stop producing until late fall.

    We also had cucumbers, peppers, SunFlower with a bumber crop of seeds, and peas. The only suggestion I have is plan for the squirrels that will raid your farm daily. They tried to eat everything we planted.

    Since we were so sucessful last year, we have already built a new cage to place over our garden and look forward to the savings.

    Good Luck!

    • what exact varieties did you plant? I’ve grown a bunch for the past 3 years but none that made me delirious. I want sweet and meaty with thin non-metallic skins. Cherry or regular – still looking.

  • A “determinate” variety of tomato will attain a smaller, more manageable size for container gardening. You’ll still need to stake them though, but the plants won’t get as large as an “indeterminate” variety. The fruit of a determinate variety, however, will tend to ripen over a shorter period of time. Some of the determinate varieties you’ll see labeled as patio tomatoes.

  • It gets hot, hot, hot on our roofs in the summer. Prepare to water daily if not morning and night. Peppers do extremely well, tomatoes tend to split due to the stress of being heavily watered and then baked all day.

    My Hibiscus trees like it, but have to spend winter inside.

    • piece of advice on peppers (at least of the chile variety): if you plan to dry them out and keep them around long after the season ends, make sure you dont keep them in an air tight container. I left my pepers out on teh counter to dry last year and once I thought they were good, put them in a zip lock bag. turned out tehre was enough moisture in there, even though they looked dry, to rot them all. I managed to get a few more off the plant after that and they were fine as long as they were able to air.

  • Cherry tomatoes do better in containers than larger tomatoes which, as pop-up owner says, tend to split.
    Eggplant, cucumbers, zuchinni, even watermelon all do ok in containers but everything takes a lot of work and the latter 3 will need room to sprawl out all over the place unless you train they to do otherwise – again, lots of work. Make sure your roof can handle the extra weight of soil that will occassionally be saturated with water.

    • Wow! Thanks so much for the advice about the weight. The roof has a deck, but to avoid taking up that space, I was going to put them on the actual roof. Didn’t even think about the added saturation weight, and I’d hate to unintentionally find a weak spot on the roof. That’s great advice!

  • I’ve never grown a rooftop garden, but I have done some extensive sideyard horticulture for the last several years. In my experience, just about any herb or veggie you regularly eat will grow fine in DC. Just make sure you water least every morning, and check on your plants every evening too. If you’ve got limited planter space, go for plants in the relatively small and upwards-growing category: tomatoes are obviously great, so are peppers, basil, chives, parsley, mint, and arugula. You can also grow things like carrots and lettuce in planters, but those don’t tend to be as worth it if you can’t plant a lot of them. Same thing with climbing plants like beans and peas – you really have to plant dozens of them if you want to get more than one dinner’s side dish out of the effort. If you have more space to let your plants spread out, the ones with large roundish leaves tend stay low to the ground but take over large areas: cucumbers, zucchini, cantaloupe, pumpkin, and anything in the squash family.

    Have fun and good luck!

  • You should actually water in the evening, after the sun goes down. The water has more time to soak into the soil before the sun warms the earth and evaporates it.

    Planting tomatoes, peppers, squash, eggplant, etc. if a great way to supplement your diet. I had so many tomatoes last year I gave 2/3 of them away. I grew Better Boys, Romas, some Cherry tomatoes and one Cherokee purple. The Better Boys were great, the Romas and cherry tomatoes pretty good, and the Cherokee Red tasted awful and produced very few fruit. I also grew Hungarian Hot Wax, Thai Red, Anaheim and Bell Peppers, all of which did really well and were delicious. I froze about 2 dozen bags of peppers, and I am still using them now.

    • This is wrong. Water in the morning. Otherwise you get root rot.

      • Correct – watering in the evening also makes the plants more likely to get fungus. And slugs love the moisture.

        • How do slugs get up to the roof? And if they do, I kinda think they deserve anything they can munch up there.

        • There’s always been a battle between the morning/evening watering proponents. I’ve been growing vegetables for about 25 summers, and never had root rot or fungus problems watering in the evenings. The keys are not to overwater, and to water the soil, not the leaves.

          Root rot especially is the result of overwatering or poor drainage; if you let your plants sit in water, regardless of when you water, you’ll have problems. If you tend to overwater, maybe morning is better for you, since at least 30% of what you put on the soil will be evaporated within a couple of hours of summer sunlight. As for fungus, if you water the soil and not the leaves, it has no effect on fungal growth. Depending on your watering method, you may need to take that into account.

          Good luck with your rooftop garden–you’ll enjoy both the experience and the harvest.

  • Grow a smaller, bush variety or a determinate type of tomato. Romas work well too. Cherries are indeterminate and will vine upwards of 10-12′. So are most heirlooms.

    Peppers, especially hot peppers, are fantastic and will produce all summer long.

    Use plastic planters rather than terra cotta to retain water. Water in the morning, not at night because it can create fungus, and water the soil only (not the leaves).

    And please please please don’t buy your plant starts from a Home Depot. They are usually riddled with soil-borne blight, funguses and viruses that will wipe out your plants before you know something is wrong.

    Squash and cukes are vines and need lots of space to ramble.

    Grow lots of herbs; they love the sun. Basil can get a little wilted, so give it some protection from that afternoon DC sun, but others should be fine.

    And good luck!

  • rosemary grows like a weed in dc. don’t know about a roof, my rosemary in my direct sunlight south facing front yard grows like mad.
    but my dirt is dry as a rock right now and my rosemary has not lost a beat all winter.

  • I used to have a roofdeck garden and think the hardest thing about rooftop gardening was remembering to water every single day (maybe both morning and evening). If you forget once everything wilts and never really looked good again.

    If I did this again I would definitely try to set up some automatic watering – you can get relatively inexpensive timers and hoses at Home Depot or Lowes and run small water lines to each pot. Seems like it would be a pain to set up the first time but I’m sure it would pay off – I want to try this for hanging baskets on our porch this summer.

  • The book “The Bountiful Container” is the bible for growing edibles in containers. The authors are McGee & Stuckey. I cannot say enough good things about this book—they give you detailed information on growing different vegetables and herbs—whether to start from seed or seedling, what varieties work best in containers, what size container to use, etc.

    And best of all are the “theme” garden suggestions sprinkled throughout the book—e.g., what vegetable/herb combinations to grow if you like Asian cuisine, or to cook Italian, etc.

    A good book for city roof/balcony/terrace gardening is Linda Yang’s City Gardening Handbook. Ms. Yang is Manhattan-based–so her book talks a lot about container weights and watering and how not to cause damage to your balcony and/or the residents below.

    And if you have access to an outdoor hose bib, look at for their drip watering kits which can be used with container gardens. The system is relatively easy to put together, operates on a timer, and is totally worth it. Happy gardening!

  • Highly recommend “The Bountiful Container” as the bible for growing edibles in containers. They give highly detailed info on every vegetable and herb—including what varietals are best for containers, what size container is appropriate for each, watering needs, etc. Bonus are the “theme” garden recommendations sprinklered throughout–the authors suggest vegetable/herb combinations for asian cooking, or italian cooking, etc.

    Linda Yang’s City Gardening Handbook has good info on weight and water considerations for urban gardeners. She’s a Manhattan-based gardener, so she’s very attuned on how not to flood your downstairs neighbor or create other garden-related problems.

    and for automatic watering is totally worth it. Once you’ve set up the system (you need access to an outdoor faucet), it runs on a timer. The system is perfect for container plants.

  • Depending on your interests, you might want to skip the plastic containers. Yes they retain water and are readily available, but with the hot summer sun, they could leach toxins into the plants via the soil. If you don’t care, then plastic would be a good option (skip out on the black plastic as it will attract more sun requiring more water).

    Soil is way important when it comes to container gardening. Make sure you get POTTING SOIL. Anything else will not have the right drainage or nutrients to carry your veggies/fruits through the seasons.

    Organic fertilizers, amended to the soil, will help, including Bone Meal (to help the plants flower, producing more fruit), Blood Meal (for plants that are heavy nitrogen feeders), and compost tea (this is just compost mixed with water). You can pick these up at Home Depot (Bone/Blood Meal) and Whole Foods (Silver Spring).

    If you can, pick some Heirloom varieties. They preserve our plants’ genetic diversity and often taste better than regular varieties. Tomatoes, for example, come in an array of shapes and colors, including green, yellow, purple, pink, orange, and of course red. You can pick up a ton of Heirloom seeds at any Whole Foods. This is the brand name:

    Certain vegetables can be sown now including peas, lettuce, spinach, broccoli, radishes, beets. You will need deeper containers for the root vegetables. Once these have grown it will be just the right time to put your warm weather vegetables out. Tomatoes, peppers, and herbs.

    I find that Basil will grow easily. Mint will as well, but plant in its own pot as it will overtake anything else. Tomatoes/Peppers are pretty easy to grow. I’d recommend planting one tomato/pepper plant per pot. They will grow better and produce more fruit.

    It’s true about the determinant or bush varieties of tomatoes. They will stay relatively small and manageable.

    The best time to start your tomatoes/peppers would be within the next month or so. Start the seeds indoors, then transplant the seedlings into larger containers. Only put outside after April 15th or an unexpected freeze might kill them off.

    Oh, and make sure you put out some flowers to get pollinators to help you out.

    This book has been an inspiration to me for the past year:

  • Hi everyone – I recently started a blog about gardening in the city. It’s largely focused on food policy and food systems planning, but I have a DIY section and there are plans on there for “self watering” planters using recycled materials or things you have around the house – for example, yogurt containers for herbs. I’ve also engineered self-watering growboxes out of those 18-gallon tubs I picked up from Target. I’ll be posting info on that on the blog shortly. My problem last year was that when August came, I couldn’t keep the soil moist enough despite morning and evening waterings. Hopefully these self-watering planters will fix that. You can check it out at Thanks!

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