Feel your sap rising but don’t have a place to get down in the dirt? Are you quietly pining for a swatch of land to grow a few sweet tomatoes or crunchy-crisp lettuce?
Coworkers at Harvard Business Publishing in Boston are and, eager for the chaos only Mother Nature can bring, bravely launched into the second year of their rooftop garden. Any time we have the opportunity to turn white collars green, we’ll take it – so let’s celebrate the efforts of Martha, Matt, Susie, Matt, Doug, Zach, Tara, and Roisin with a bit of advice on container gardening.
Ok, you’re on a roof; it’s accessorized with air conditioning units, pipe stacks and other roof things. So, a few ground rules:
1) Keep your plants away from intake fans. Though the screens might have you thinking “hey, what a great trellis!” do not give in to temptation. These fans provide persistent suction, pulling air into offices below; chopped plant parts sailing through the building are not a pretty sight, and no, it is not a way to freshen the air.
2) See the gutters? They’re for channeling water away from the building, not for bordering your garden with pretty posies (you’re in the Northeast, you get rain! We don’t in Colorado, at least not much. Do not do as we do and reinforce the supports, fill them with potting soil and plant low growing flowers (see photo). We’re crazy; you’re not).
3) Get to know your facilities people; invite them to visit your garden. Chances are there will be muddy shoe prints, a few bits of plants dragged indoors, and the odd leak or two. You need these fine people on your side.
4) Get ready for birds. Eventually they will believe that the garden is there for them, not for you. Plan on protection such as netting, flashing mylar strips, or one of the executives that really doesn’t have anything better to do. Cover your seating area when you leave to go back to the office.
5) Bugs fly. They’ll find your crop tasty too. Check with your group to get a consensus on pest management. Don’t automatically assume you can spray whatever you want to around intake fans (see item number 1, and add a floating cloud of…well, you get my drift).
OK, now for a bit of advice. When choosing pots for your plants, make certain you have drainage holes. To avoid problems from lead leaching into your soil, go with pots that don’t have a glaze on the inside. Clay, plastic, metal, wood – the choice is yours, but be aware that you’ll need to pay closer attention to watering plants that are in porous pots which wick moisture away faster than plastic, metal or glass. Anything can be a container.
Don’t be boring – mix up the size and colors of your containers. Group plants together in nice communities, varying the number of plants in the groups and occasionally placing a few singly around the area.
Keep in mind that vegetables need plenty of root space to be productive. There’s a great list of pot sizes and soil volume per plant type in The Ohio State University factsheet on container vegetable gardening. Clean potting soil is best; don’t reuse soil left over from last year.
Once you’ve planted your garden, remember that those plants are now dependent upon you to provide for their nutritional needs. In other words: fertilize them. Container plants need extra care, since they can’t access naturally occurring nutrients. Balanced fertilizers are best; if you’d like to add a timed release into your soil mix, blend it in well before planting. Follow the ratios for mixing on the label.
What varieties should you plant? Depending on the size of your containers, look for compact plants to do better in containers. Several All America Selections are wonderful for this: Carmen pepper (most peppers work well in containers), purple Hansel and white Gretel eggplants, which provide sweet, tender fingers of fruit; or Honey Bear acorn squash.
Bush beans do well, but you’ll get more production from a deeper pot and pole beans running up a trellis, or try letting melons ramble across the roof. I love Charantais, the small, succulent cantaloupe from France. But you need a bit of experience to tell when it’s ripe, otherwise it has the bad habit of exploding – a drawback if you’re sitting near one in your business clothes.
Plenty of tomatoes do well in containers. Try Early Girl or Celebrity for slicers, Sweet 100 or Tomatoberry for cherries. The list for tomatoes in containers is a long one; it’s best to check out the habit of the plant before you buy it. Go with compact plants and provide a cage for them.