Feed the soil with green manure crops

At yesterday's Harvest Basket I was talking with Linda and Dave about soil. They have been in their house about a year and are getting a veggie garden established in their front yard. Up until now it has been lawn and the soil sounds as if it is poor and sandy.

I suggested growing a green manure crop to remedy this, but didn't have time to elaborate.

Although a lot of experienced gardeners use green manure regularly, it sounds like there are plenty out there who don't know about this great, low-cost and low-effort way of building a rich, living soil in their veggie patch.

The basic idea is as follows: in a bed that you don't need for a few months (at least 10 weeks), you sow seed very thickly to produce a lush, green blanket of young plants. These will out-compete any weeds that might germinate in your soil.

It's a good idea to net the bed until the seedlings are up, otherwise the pigeons and sparrows will have most of your seeds. You'll end up with fat, healthy pigeons but little else to show. (I've often considered harvesting the pigeons, but Susan isn't keen.)

When the young crop is about 20 cm high you slash it down and dig it into the soil, where it rapidly breaks down, providing food for microbes, earthworms – and of course the veggie seedlings you're going to plant into the bed.

It's important to dig in the green manure crop before it starts to get tough and woody, otherwise it will take a lot longer to break down.

Green manure is a way of keeping the soil 'working' until you need the bed. Watering needs are lower than with a food crop; if you sow the green manure in the colder months you shouldn't need to water it at all once the seed has germinated, unless there's a very dry spell.

Typically a green manure mix will contain legumes such as beans, peas, lupins, with grasses like barley and rye. These nitrogen-fixing plants are ideal for a bed where you intend to grow hungry plants like cucurbits (pumpkins, zucchini etc) or brassicas. Van Loons sell a good mix in 500g bags, or you can use your own left-over seeds from last year.

You can also choose your green manure for specific purposes. For about 3 years now I've been using mustard as a bio-fumigant green manure. It is supposed to clean the soil of fusarium (causing wilt in tomatoes etc) and repel harmful nematodes. It seems to work: I've had great, healthy tomato plants ever since and haven't lost one to wilt, whereas I used to lose a couple of plants each year prior to this. (Typically they would grow well until first fruit set, then the leaves would curl and turn purple and the plant would die.)

Diggers do a bio-fumigant mustard mix, and Green Harvest do a whole range of different green manures for specific requirements.

Quick update on the wicking bed (see July post)

I've been adding salad and herb seedlings to the bed these last couple of weeks and they're all looking fairly perky. We've had 36mm of rain this week but the bed appears to be draining well. I suspect that the sandy soil mix has been important in this regard, even though it went against all my instincts - I'd normally have a rich mix of compost, lucern straw etc in a raised bed. It will be interesting to see how things go once we get into the dry, hot summer months.

Tomatoes galore

It's the end of May and tomatoes are still ripening in our garden. Not many, but enough to make me procrastinate about pulling out the vines. They'll have to go soon, though, to make way for the broad beans.

Everyone I've spoken to in the Geelong area to seems to have had great tomatoes this year. We've had the perfect summer for it, with decent rainfall and warm weather without searing heatwaves to frazzle the vines.

I always grow my tomato plants from seed, and always heirloom varieties, which crop for longer and (I think) have more taste. I grew Tommy Toe and Amish Paste varieties this year (seeds from Diggers Club).

Tommy Toe is the mainstay of our tomato crop each year: they grow like weeds in our garden and the fruit is great for sauces, salads, on pizzas - you name it. Amish Paste was a first-time experiment. Despite the rather unappetising name, they're a good medium-large slicing tomato, sweet with low acidity.

Amish Paste do seem prone to blossom-end rot, though, and I lost a large part of the early crop, yet no trouble with the Tommy Toes right next to them! Regular doses of Tomato Magic seemed to help correct the problem, but I doubt this is an allowable organic input, so next year I'll try harder to get the soil calcium right before I plant.

Speaking of soil prep, I've never lost a tomato plant to wilt or nematodes since I started growing mustard as a bio-fumigant two years ago. (The young leaves of the mustard make a nice spicy salad crop too.) Sow in winter, then, before the mustard flowers in the spring, smash it down and dig it in. You can plant tomatoes into the bed within a couple of weeks. Works for me.

Tomato sauce recipe (works best with small, sweet tomatoes like Tommy Toe):

• Enough whole fresh tomatoes to cover the base of a roasting tin or ovenproof dish
• Extra-virgin olive oil (we always get ours direct from Lighthouse on Anderson Road)
• A good pinch of sea salt
• Fresh oregano or cinnamon basil leaves
• A couple of cloves of garlic
• Optional: a glug of vino cotto, balsamic vinegar (don't overdo it) or red wine

Roll the tomatoes and herbs in the oil to make sure they're well covered. (Go on, get your hands oily!) Put in a preheated oven at about 180 C for 90 minutes or until the liquid is starting to reduce and the tomatoes are caramelised on top. Leave to cool, then whizz up in a food mixer. Will keep in the fridge for 7 days, or freeze in small containers.

I've never bothered sieving the tomatoes, though you could if you wanted a smooth paste.

Alternatively, just serve the whole tomatoes hot from the oven with roast meat or with pasta.