Gardening: Making a living sandwich

Justin Newcombe with his no-dig or sandwich garden. Photo / Richard Robinson

Landscape gardener and Life columnist Justin answers your questions.

I'm about to start a new garden in my new townhouse for spring. I read something about "sandwich" gardens - are they the same as no-dig gardens? What should I start to layer into the beds to build up the soil for spring planting?
- Sarah

Yes, the idea is the same as no-dig gardening. Another name for this type of gardening is sheet mulching. If you are starting the garden as a new plot on grass you will need to put down a thick layer of moistened newspaper or cardboard. This will keep the grass and weeds at bay while your garden establishes. Next place a manure layer over the cardboard. This could be cow manure or another semi-composted material or you could do a mixture of soil and kitchen scraps. Next place a compost or soil layer on what you will be planting into and finally place on a mulch layer which is best done using pea straw. Don't forget to repeat this process every time you replant your garden and I'm sure you'll be really impressed with the results. Interestingly, you'll find a very big improvement in the soil below your sandwich garden even though you haven't turned a sod.

The last of my grapefruit trees got blitzed in the snow/frost last week. The fruit is now mushy on the branches. Will the rotting fruit affect the tree, or should I take them all off? Will it affect their flowering and fruiting for next autumn/winter or is there something I should do now. The lemon trees were unaffected.
- John

Yes, you are correct, remove all of the affected fruit from the tree. By leaving even marginally affected fruit on the tree you may risk a botrytis infection later in the season which could spread and affect flowering and next year's crop.

I have had some lovely coprosma hedging bordering my gardens, but over the winter a couple of the plants in the hedge have died - not sure why, as the others are still healthy. It is an unusual chocolate variety that I got from a nursery that is now out of business. How can I strike new cuttings to fill in the gaps in the hedge? What do I need to do to the soil so the new babies don't die too? It is very clay-ey soil.
Thanks, Margaret

I have seen this many times. The variety of coprosma you have is derived from alpine stock and is at home in dry, airy conditions with little humidity or ground moisture. These varieties are susceptible to fungal infections in the roots as well as the foliage so care must be taken when trimming. Your tools must be sharp and you must remove all of the jettisoned foliage from around the plants. Also make sure the soil is not compacted; you may need to gently fork in some aeration holes. Lightly feed with leaf mould (composted autumn leaves) if you have it or a 50/50 mixture of compost and crushed, dry brown leaves. Lastly don't water the foliage. Instead ground water with the water pouring straight out of the hose, no sprinkling. As far as repairing your hedge goes buy some new plants. This will be the fastest most reliable way, besides, this will in all likelihood not be the last time you face this problem with your lovely hedge.

I have a beautiful old fig tree that had started to get rot in the biggest branches coming off the main trunk. I cut back all the small branches and the bigger limbs that I could see that had rot in them. Now I am worried I was too heavy-handed. Do figs recover from a heavy-duty prune? Is there something I can put on the remaining trunk and branches to stop the rot?
Thanks Eileen

In theory, your fig should start to grow back as the weather warms up although don't expect any fruit this year. If there are any remaining areas of the tree still affected by rot, check the tree for signs of borer. This can be treated by pruning back the badly infected areas and applying pyrethrum to any lesser-afflicted areas. Figs dislike wet feet but I'm assuming that as it is a well-established tree this is probably not an issue. If you suspect that drainage has become a problem though, you could carefully fork in some gypsum around the drip line of the tree. Give your fig a bit of TLC by applying some compost and mulch at its base as they are very shallow-rooted.

GARDENING CHECKLIST
In the vege garden
Time to start germinating seeds indoors for spring. If you only have limited time or space, make sure your top performers get priority.

Tomatoes can be germinated now. Start with early bearers rather than the bigger, late summer varieties. Cherries or cocktails, early money and blood butcher will all give a good account of themselves early on.

Potatoes can be chitted (sprouted) and you'll find a good variety at Bunnings. Make sure your ground is well prepared with blood and bone and even potash. I haven't had time this year but in the past during autumn I've trenched-in seaweed and have had excellent crops the following year.

It's very important not to plant your spuds in the same place twice nor in the same place as any other plant from the nightshade or solanaceae family.

Chillies should be germinated in trays and a wide variety can be sown from now on. Keep the seedlings well watered. Do make sure you wash your hands after handling them because even though the seeds themselves don't contain any capsaicinoids (that's the hot stuff) the white membrane around the seeds has the most concentrated amounts of the entire plant. To get a comparatively early crop consider growing some in pots so they can be moved indoors during cold weather. These will also likely winter over, giving you a head start next year.

Egg plants are slow to flower so the earlier you get these started the better. Consider growing this crop in a cloche or poly tunnel. This will give an extra couple of degrees warmth and the contained heat will also extend out the daily growing hours.

Kumara are one of my absolute must-grow crops. You can take the boy out of Dargaville but you can't take Dargaville out of the boy. Place some tubers in a box or plastic bag half-full of sand, leave in a sunny spot.

The shoots will appear and once they are about 10cm long can be easily broken off and planted out. Place a handful of charcoal under each shoot and stake the vines like tomatoes. This stops the tendrils spreading throughout the garden and stops the vines from attaching to the ground and growing smaller less desirable tubers.

Other seeds to start this fortnight are peas, beans, lettuce, rocket, small cabbage, radish, beets, carrots, and summer herbs like coriander and basil.

Don't forget to include flowers in your vege garden. Sow salvia, begonia, sweet peas, carnation, celosia, snapdragon, cosmos, delphinium, stock, dianthus, zinnias, forget-me-not, larkspur, linaria, cornflower, lupin, marigold, nemesia, pansy, candy tuft, phlox, alyssum, linum, statice lobelia, petunia, violas, poppies, sweet william, and portulaca.

In the fruit orchard
Fruit trees are starting to blossom, so make sure they are fed mulch. Use seaweed if you can. Compost the trees but be sure to mulch over the top. Compost makes terrible mulch on its own as it sets hard and deteriorates in the sun.