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Q SEED SOWING

I’ve tried growing flowers and veges from seed with mixed results. Germination is patchy and the tiny seedlings often die. Would a heated seed-raising pad help? HELEN COLLINS, DUNEDIN

A

It is possible to grow many plants from seed without a heat pad but results can be erratic, especially in winter when we’re trying to get a jump start for early spring planting. One of the problems is temperature. A seed tray cossetted inside may experience wildly varying conditions, from scorching on a sunny windowsill by day to freezing next to the glass by night. The steady warmth of a heat pad or a spot on top of the fridge does promote better germination. Seeds are not all equal – each species has its own requirements for

optimum germination. Temperature affects both the percentage of seeds that germinate and the rate of germination. Look at the fine print on seed packets and you’ll find that lettuce can cope with a range of soil temperature from 10-25°C, chillies are much happier at 20-25°C but broad beans prefer 7-10°C.

Heat pads can be pricy. Shop around and consider DIY set ups using home brew fermenting pads, water bed heaters or LED lights. Weigh up the cost against the number of seedlings you’d like to grow and the advantages of having access to special varieties that aren’t commonly available from garden centres.

When baby seedlings collapse and die overnight, the cause is a fungal disease known as damping off. To avoid this problem, always use fresh, sterile seed-raising mix. Sow seed thinly, use a mister to keep the mix moist but not saturated, and provide adequate ventilation. Barbara Smith

Q SICK FEIJOA TREE

Last winter we planted two new feijoa trees in a very high wind zone on the eastern hills of Lower Hutt. Our soil is, well, bedrock with a thin clay cap. We put up wind shelters and kept them watered through the summer. They both looked very well until one lost all its leaves over the course of a couple of weeks in late summer, and now the second is performing the same trick. The leaves show no sign of discolouration or damage and I have checked for collar rot. What has killed our lovely trees? DELIA STRONG, LOWER HUTT

A

While feijoas generally tolerate difficult soil conditions, I think that the rock with a thin layer of clay is providing insufficient moisture and nutrition for the trees.

In order to revive the tree that is still alive now, I suggest transplanting into a new position. The new hole should be large, at least 1m x 1m. Backfill with a mix of good quality soil and potting mix. Winter is the best time to transplant trees, as it’s the lowest stage of growth (for evergreens) or dormancy (for deciduous trees).

Transplant carefully to avoid root disturbance as much as possible. Kate Marshall, Waimea Nurseries

Q CAMELLIA SPOTS

There are brown spots and yellowing leaves on our recently planted ‘Early Pearly’ sasanqua camellia hedge. How can I fix this? I have read that camellias can get some diseases. ROSE CRAIGIE, CHRISTCHURCH

A

We sent your pictures to camellia expert and plant breeder, Mark Jury, of The Jury Garden in Tikorangi, north Taranaki. Mark replied that it’s nothing to worry about.

“There has been some leaf roller caterpillar damage from earlier and it may have glomerella, which is very common in camellias but will have no long-term impact.

“The lower leaves look to be in excellent health and the plant will be preparing to make new growth. No action is needed and the plant should grow away well as temperatures rise.”

‘Early Pearly’ is a particularly good variety for hedging as it has a naturally upright form. It’s a good choice for espalier too.

Camellias are prone to petal blight but careful choice of plant variety and routine garden hygiene minimises issues with unsightly brown, mushy blooms.

Autumn-flowering sasanquas bloom before petal blight is active. Blight is less obvious in varieties with multiple small, single flowers like the Jury hybrid ‘Fairy Blush’. Brown blotches aren’t as obvious on large red reticulatas like ‘Glowing Embers’ either. The heavy blooms self-groom so the tree still displays well. Barbara Smith

Q USING SEAWEED

I collect kelp from the Petone foreshore. Can I use it around flowers as well as on the vege garden? How can I get the most from this kelp? And what is the best way to process it? ETHNE ANDERSON, LOWER HUTT

A

Seaweed is an excellent soil conditioner. It’s free, widely available and packed with nutrients. Kelp in particular has high levels of vitamins, minerals, enzymes and natural growth hormones. Use as mulch, add to the compost bin or dig it into the soil. Seaweed can be used around both veges and flowers.

Kelp breaks down faster if it’s chopped up. Use a sharp spade or lay the kelp out on the lawn and run over it with the lawn mower.

Layer with carbon-rich woody prunings or cardboard when composting nitrogen-rich kelp, as it will go slimy by itself.

Opinion is divided on whether it is necessary to rinse salt off seaweed. I don’t bother myself but if you are using large amounts leave it out in the rain for a while or give it a spray with the hose.

Kelp also makes a great liquid fertiliser. You don’t need much – put some in a barrel, add water and leave to mature into brown sludge. Place well away from your outdoor living areas (and the neighbour’s) as it is extremely smelly! Dilute about 1:10 so it’s the colour of weak tea and use as a foliar feed or water into the soil.

Check the regulations for your area before collecting seaweed as there are restrictions in some places. Barbara Smith