Q&A

YOUR GARDENING QUESTIONS

- Your questions answered.

Fattening fennel and celeriac

I have not had any luck getting celeriac and fennel to produce a crop worth harvesting. Does the depth the seedlings are planted or the soil type prevent them developing fully?

ANNA WOLTERBEEK, MASTERTON

Both celeriac and fennel can be reluctant to bulk up if they’re watered irregularly. Or maybe it was the time of year and the growing conditions. Both crops prefer cooler growing conditions rather than the heat and lack of rain during summer.

Keep Florence fennel happy by growing it in spring and autumn, rather than over the heat of summer. You can sow seed direct or plant seedlings. Treat seedlings with care when transplanting, as Florence fennel resents root disturbance and will quickly bolt to seed.

Give Florence fennel full sun and a free-draining, welltilled soil. This crop prefers an alkaline soil, so add lime before planting. Keep it well-watered to avoid woody stems. As the bulbous base begins to swell, mound up the soil around it to keep it upright and white.

Fennel bulbs can be harvested from the size of hens’ eggs right up to fist-size or bigger. However, smaller bulbs are generally the sweetest.

If you cut off the bulb above the ground new bulbs will grow from side shoots.

Sow celeriac seed in trays under cover in late winter in warmer regions and transplant when established, or sow direct or plant seedlings from spring until early summer. In cooler parts of the country, sow in trays inside from early spring and sow direct or plant seedlings outside from midspring until early summer.

Give it a spot with cool, moist soil enriched with compost and sheep pellets where there is morning sun and afternoon shade. Avoid using high-nitrogen fertiliser as this produces leafy top growth at the expense of the edible part. Remove side shoots so the plant puts its energy into fattening up the root.

Water both celeriac and Florence fennel regularly and mulch to retain moisture. Both plants are also prone to aphids especially if they’re stressed by drought.

Barbara Smith

Off the scale

These white dots have appeared all over the stems of my ‘Golf Ball’ pittosporum hedge over summer. Is it caused by the weather which has been extremely hot and dry? Will this infestation damage the plants? Is any treatment or action required?

RAEWYN CREEVEY, WHANGAPARĀOA

This is white waxy scale, which is very common on pittosporums – so common in fact that it’s sometimes called pittosporum scale.

Sap-sucking scale insects of all types can be tricky to get rid of because they are shielded by a protective coating which may be soft, hard, foamy or in this case waxy. Hidden underneath they tap into a stem or leaf and suck the sweet sap – weakening the plant and potentially transmitting viruses. Scale excrete honeydew which attracts wasps and bees and also hosts a fungal sooty mould which covers the leaves, reducing photosynthesis and further debilitating the plant.

Waxy scale are at their most vulnerable as juvenile crawlers, the mobile first instar stage which hasn’t yet developed a complete covering. In New Zealand there is one generation a year. The eggs are laid in summer and hatch from January onwards.

Smother scale insects with horticultural spraying oil. Good coverage is essential. Spray every nook and cranny until the leaves and stems drip.

To get this badly infected, the plants were probably stressed in some way. Lack of water, irregular watering, high temperatures or a lack of nutrients may have contributed to the problem. Try liquid feeding with a seaweed-based fertiliser to help them recover after you’ve tackled the scale.

Barbara Smith

Spring blossom in autumn

At the end of March we’d just picked the last ‘Splendour’ apple when the tree blossomed again. What will happen when we get the first frost? Should I leave the blossoms alone, or cut them off to prevent problems when spring really arrives?

JANET MOLES, DANNEVIRKE

A double harvest in one season isn’t unknown in apples. In an early or midseason cropper, it’s possible to get ripe fruit twice – say in January and May. With a later cropper like ‘Splendour’, it’s less likely that this flush of flowers will get a chance to fully ripen.

A second flowering is more common in hot climates, and it may be down to the tree being stressed from a hot, dry summer and reacting to a moist autumn by blooming again.

In Southern California this is common and gardeners report good yields from both crops but some experts do recommend removing the flowers to allow the tree to rest during its winter dormancy so it has the energy reserves to produce more blossom next spring and support a better crop through to maturity next autumn.

Barbara Smith