Justin Newcombe works out the secret to a healthy of crop of beans, to be eaten fresh, or dried and stored for winter.
Many of my favourite beans are not that big in stature - in fact they are quite shrubby - but really flavoursome. Some are good for drying. The beans I'm talking about, traditionally from either the French or Italian Mediterranean, are colourful and succulent when they are fresh, and when dried make an excellent addition to winter soups and stews.
My previous attempts to grow many of these have been thwarted by in-ground mealy bug attacks. That's not to say I haven't had some success, even though that success has been measured by the handful and not the bucketful. With only a small residential garden, I'm a bit wary of trying to grow crops that need to be stored, but I have made some exceptions - notably garlic and pumpkin, both of which usually prove to be very successful. I would like to find a way to have the same success with the group of meaty bean crops.
The first thing I have to come to terms with is that I don't live in the Mediterranean, so I need to do what I can to recreate the conditions of the Med. That means limey, free-draining soils which are either volcanic or rocky with lots of dry heat and crisp mornings. That sounds a long way away from muggy old Auckland, so my best bet is going to be to enlist the help of a secret weapon, a thermal mass.
A thermal mass is, in gardening parlance, a wall of some description. It could be a shed, fence or, if you are lucky, stone wall, which will reflect and store heat. This creates a regular, warm micro-climate to keep the plants warm and protected from wind. I should point out the wall needs to be north-facing to get the best of the sun; obviously the south side of a wall will have the opposite effect.
Once I've got my Mediterranean position I need to create my Mediterranean soil. My soil is like much of that around New Zealand, a bit on the heavy side and lacking in calcium. Some of us are very lucky to have soil on a river plane or from a volcano or in some cases a bit of both (take a bow, Ruawai). I need to improve my sedimentary up-lifted soil (even the name sounds heavy). The first thing I do is add calcium which will help improve the tilth of the soil by breaking up the tight particles and help the soil particles hold on to micro-nutrients. Another option is to dig small date-sizes pieces of concrete into the soil to try to mimic the rock nature of the Med.
Add a little blood and bone and a small amount of potash. The soil needs to be dug into a really fine tilth, so avoid soils with a lot of un-composted carbon material in it. This will only help to attract mealy bugs, which you don't want.
Choosing the beans is the easy part. I'm going for a row of bush beans, albenga dwarf and a pole bean called lima del papa or the pope's bean.
This should give me the bright scarlet beans I'm after and the option of eating now or drying for later. We're still growing some runners and broad beans because we like that with both those varieties, the more you pick the more they yield. As for the mealy bugs, I'm watering my beans with a mixture of water, pyrethrum and garden friendly dish soap. The soap will help dilute the pyrethrum in the water, and will also help the water to penetrate the soil, putting a stop to any unruly mealy bugs snacking on the roots.