I have yet to talk to a burgeoning food gardener who isn't intent on growing their food organically. But organic growing involves developing a whole new body of knowledge about just what is an organic practise, or what tools and practises are available to an organic grower for things like pest control.
So we thought we'd talk about some of the practises we use - here and in our next two posts, about fungus prevention and control - those dreaded plant diseases like downy mildew or late blight!
Your best tool is, of course, prevention:
Buy only healthy plants: this is obvious - I mean, who would bother spending money on a half-dead plant? But it's still worth having a general look around the nursery or plant store before you start choosing your plants, to be sure that all the plants look healthy and disease free, and you aren't bringing home a Trojan horse of a kale plant, in your very own hands. Diseases can also be spread via the seed you buy, but since you can't diagnose that on the spot, the best you can do is to keep close track, over the years, of which seed companies sell reliably good seeds. Or ask your gardening friends.
Interplant your crops: that is, consider arranging your plants so that you are not just mono-cropping in each little area of the garden. Having a whole lot of the same plants in close proximity means that it's easy for a fungal disease to spread rapidly from plant to plant. Instead, for example, plant your tomatoes more widely spaced, interplanting them with basil (on the sunny side of the tomatoes) and parsley and greens (on the shady side), so that each tomato plant is surrounded by a ring of non-tomato plants - disparate islands of ready-to-make spaghetti sauce!
Get to know your plant families: For example, potatoes, tomatoes, tomatilloes (photo below) and eggplants are all members of the nightshade family, and can therefore easily share diseases with each other. So when you're considering interplanting or crop rotation, you need to think in terms of plant families as well as individual plant types: don't plant your tomatoes where you had tomatilloes last year!
Similarly, the brassicas can also share diseases or insect pests. These are the cruciferous vegetables, all members of the mustard family, and include kale, cabbage, broccoli, cauliflower, arugula, and brussels sprouts, among other edibles.
Air circulation and thinning: Fungi thrive in moist conditions, so above all, you need to ensure good air circulation around your plants. For crops like kale, chard, lettuce and other low-growing plants, make a point of properly thinning out your plants as they grow. If you are unsure of how far apart plants need to be, you can follow the instructions on the seed packet.
But rather than doing the thinning in a single pass, spacing the little seedlings out drastically all in one go, we tend to do it in several passes over the progressing months. This way, we are able to take harvests of the growing plants as we thin. In order not to disturb the roots of the nearby plants, we just snip off the tops of the thinned plants, rather them pulling them out, root and all.
The photo (right): this crop needs thinning! We went a little crazy with the kale seeds in the spring - and got a nice fat bunch of kale to grow. Except we got lazy and never thinned them. So we lost the whole crop to mildew later in the summer. Lesson learned - and we missed out on such good eating!
Reach for the sun! For plants like squashes and cucumbers - very susceptible to mildew - route them up a growing frame. Tomatoes can be tied up on cages, stakes or trellises - and same for any other plant that can possibly be trained upwards. Lifting them into the sun and the breezes also keeps their fruit from resting on the ground and rotting before you can harvest them.
Thin the plants' foliage - especially plucking off any plant part that is showing signs of mold, immediately upon seeing it. Even healthy foliage can do with cutting back, sometimes, especially if where one leaf is resting on another, creating a small, moist pocket where mold can take hold and spread.
And of course it's received practise to pinch out the tomato suckers - the new little shoots that sprout out where a leaf joins the stem of the plant - both creating more air circulation and pushing the plant to concentrate on making the tomatoes themselves.
The special case of the small garden: If you have a very small garden that is fairly enclosed, you have an extra challenge in creating air circulation. In this case, we recommend still more height: build double-high raised beds, or use tiered containers. Install lightweight, breezy growing frames wherever a plant can benefit from such a structure.
Plant as far from the walls or shrubbery as as you can. If possible, try to create some openings in any surrounding foliage, to increase air movement. If you need to replace your fence, consider making the new one shorter, and/or with widely spaced slats, for air and light to pass easily through (this style makes for an in-built growing frame, too). And you may want to consider placing your vegetable plants just a bit further from each other than you otherwise would.
That's Part I of the exciting work of fungus prevention! Next week - more on preventing fungus infections in the garden!