Frequently Asked Questions
Can poppy seeds be sown in-situ and should they be burried?
While you can scatter the seeds directly where they are to grow, you will get better germination if they are sown in seedling trays first then transplanted.
The seeds should be sown on the surface.
How do I grow melons in New Zealand?
Melons (eg rockmelon, honeydew melon, prince melon) will grow in most places in New Zealand.
They have a long growing season and so the seeds must be started indoors early - now!
Grow the seedlings indoors or in a heated greenhouse until planting time around the end of October / early November.
For more information see the melons culture notes.
When do I plant potatoes for Christmas?
In warmer areas, potatoes can be planted all year round.
Plant early season potatoes in August and they will be ready by Christmas.
In colder areas, sprout the potatoes in September and plant in October.
There is a risk that a late frost can set the plants back.
Come Christmas, dig around the plants for small new potatoes.
Leave the plants in the ground and continue to mound up.
They will then proceed to grow another crop of potatoes.
When growing egg-plant (aubergine), do you pick out the lateral shoots as you do with tomatoes?
Aubergine is normally grown as a bush.
Leave the laterals on and allow the plant to bush up.
I planted a number of dahlia tubers in my garden and they haven't sprouted.
Dahlia tubers should be sprouted (like potatos) first before they are planted.
Plant the tubers with the tip of the sprout just below the surface of the soil.
The usual time to plant is November, when the risk of frost is low.
If planting from a division, make sure the tuber has a part of the crown with at least one eye.
For more information, please see the dahlia culture notes.
How do I overwinter dahlia tubers?
Shorten the branches and dig the plant up at the end of the growing season.
Remove excess soil and trim off long roots from the tubers.
Burry the whole plant in damp sawdust (or potting mix) and store in a cool dry place, for example the garage.
Then in September / October, split the tuber - by this time the eyes on the crown will have swollen and become visible.
Each division should have at least one eye.
Plant the divisions in late October / early November.
For more information, please see the dahlia culture notes.
When is the best time to prune tamarilos?
If your property is frost free, you can prune it any time from harvest to early spring.
In other areas, prune after the last frost.
When we were in the UK we loved the miniature tulips which were planted in most Municipal Gardens. They were dwarf with a striped leaf.
Miniature tulips are becoming more popular.
Initially they were bred by Dutch cut flower growers but have now made their way into gardens.
When buying tulips, you have to be careful if there are markings on the leaf and / or flower.
Check that the markings are specially bred into the plant, and not because of virus.
This is especially important if the markings are irregular, i.e., different from leaf to leaf and flower to flower.
Can I add citrus peelings and cooked food scraps to a compost?
Do not use large amounts of citrus peel in a worm farm.
However, it is OK in a hot heap compost.
This is because the peel (and every thing else) breaks down first, then worms move in when the heap is cool.
You can most certainly put foods scraps into the compost.
It must not contain any meat or fat, or excessive amount of water (eg. soup).
Large pieces should be chopped up.
I grew Triamble pumpkin and had a massive crop but the flesh had thick white hard veins throughout. Any idea on what has caused this?
I would suggest the veining is caused by growing the pumpkin from seed that had been crossed with another plant in the cucurbita family (possibly a loofah).
I had the same thing happen to me once, when I crossed a spaghetti melon to a giant pumpkin.
The resulting seedling looked like a pumpkin, with orange flesh but the flesh was stringy like a spaghetti melon.
It was still edible but had a funny texture.
When growing cucurbits, it is best to only save seeds from fruits that you have hand pollinated early in the morning - before the bees become active.
Remove all the petals from the female flower and put a stocking over it after it has been pollinated.
When should I prune pip and stone fruits, and feijoa?
Stone fruits (plums, peaches, nectarines, apricots and cherries) should be pruned in summer, after harvest.
New Zealand silver leaf disease (for which there is no cure) and it infects open wood during cold and wet weather.
Pruning in the summer gives the wood has a chance to heal before the winter sets in.
Pip fruit (apples and pears) should be pruned in the winter, or after harvest.
Feijoa fruits on new wood and pruning after harvest will allow the tree sufficient time to grow new wood to flower, and hence produce fruit for the next season.
When do I prune passionfruit?
If you live in an area that gets frost, it is best to wait until October to do the pruning.
In frost free areas, prune in late winter, early spring, just before growth begins.
Passionfruit flowers on new growth, so prune back hard to the framework.
How do I tell what are aphids, white fly, scale, mealy bug and mites?
Aphids are small crawling insects often found sucking on young shoots and flower buds.
They are usually green or black, sometimes dull red, in colour.
Adults have wings.
As part of their feeding process, they produce a sweet liquid (honeydew), which is relished by ants.
Ants often herd aphids, spreading them into plants.
Control aphids with a spray of soapy water or pyrethrum.
Control the ants with bait.
White fly are tiny white insects that fly off in a cloud when disturbed.
Control with a spray of pyrethrum.
They have a very short breeding cycle and it is necessary to spray every 2-3 days in order to acheive complete control.
Scale insects have two stages, crawling and stationary.
They infect plants at the crawling stage, and one single spray with a contact insecticide that contains chlorpyrifos, eg. Spectrum, at this stage will control them.
The crawling insects then settle down and build a shield around them.
At this stationary stage, they suck the plant sap and produce eggs for the next generation.
Spraying oils mixed with an insecticide will provide some measure of control.
Certain systemic insecticides, such as confidor will also provide control.
Do not use systemic insecticides on food plants.
Scale can also be rubbed off with a piece of cotton wool dipped in methylated spirits.
Mealy bugs look like little pieces of cotton wool.
They can sometimes also be found in the roots.
Control with spraying oils mixed with insecticide.
As with scale, systemic insecticide and methylated spirits can also be used.
Mites are microsopic bugs that can only be seen through a magnifying glass.
They live in large colonies, usually under leaves.
There is usually a thin layer of silk protecting the colony.
Silver marks can be seen on the leaves where they have killed surface cells.
Control with a miticide, eg. potassium salts.
I pruned a large grapevine a few weeks ago, now all the cut points are dripping sap, is this harmful to the plant?
This is the usual outcome if you prune too late.
The roots are begining to become active and start to suck in water.
This water will then bleed if the wound has not callused over yet.
The bleeding does not seem to damage the vine and stops when leaves emerge.
Next year, try to prune sooner, say before July.
Our large cabbage tree is dying. Should we cut it out fully so that it won't infect the others around it or can we cut it back to re-sprout?
There are a number of reasons that can cause large cabbage trees to die, but the most common is sudden decline.
This is caused by the Ca. Phytoplasma australiense bacteria spread by passionvine hoppers.
There is no cure, so the tree needs to be chopped down and hope that it will resprout from the base.
To stop the disease spreading, use a pyrethrum spray to control passionvine hoppers.
Why won't my tulips flower?
For a tulip bulb to flower, it needs to be mature, well grown and have been exposed to chilling temperatures in the winter.
A Tulip, like most spring bulbs, has a pretty short growing season.
Most of the growth is in the spring, during which, it must accumulate enough reserves in its bulb that it will use to produce next season's leaves and flower.
The plant needs to be grown in full sun, and adequate moisture and fertiliser supplied.
The leaves die down in the summer, as the bulb goes dormant.
Cool moist weather in the autumn stimulates the bulb to start growing roots again.
The cool weather also stimulates the bulb to produce a flower bud, which will eventually grow into a flower in the spring.
Why won't my seedling avocado fruit? Do I need to have two varieties for cross-pollination?
Seedling avocado will take many years to start fruiting, often up to 15 years!
It is better to grow a grafted which will come true to type and fruit in 3-4 years.
Avocados have perfect flowers, meaning, each flower has both male and female organs, and do not require cross pollination from a different variety to set fruit.
When the flower first opens, only the female organ (stigma) is receptive.
After a few hours it closes.
The next day, it opens again, but this time, the stigma is no longer active but instead the stamens shed pollen.
If the flower was pollinated the day before, it will most likely set fruit.
The odd thing is there are two types of flowers, A and B.
A type flowers first open in the afternoon and are receptive to pollen.
The next morning, they will shed pollen.
B type flowers first open in the morning and are therefore only receptive to pollen in the morning.
They then open again the following afternoon to shed pollen.
If you only have one type of flowers, then the window for pollination is quite small, so the adage that you need two varieties (of A and B types) is so to increase the chances of pollination, and hence better fruit set.
Will aquilegia, lupin and cornflower grow in the tropics?
Aquilegia and lupin are cold growing perennials.
Aquilegia seeds even require a period of cold in order to germinate.
They are unsuitable for the tropics.
While the plants may grow, it is unlikely that they will ever flower.
The corn flower may fare better, as it is a summer annual, but there is still no guarantee that it will grow in the warm humid climate.
The tropics also lack the day / night temperature differential, that certain cool weather plants require.
Furthermore, the plants may be more susceptable to fungal diseases in the warm humid conditions.
None of my dragon fruit seeds grew, I planted the whole lot in a mini greenhouse. Do you know why?
Perhaps the mini greenhouse isn't that suitable.
The temperature will swing greatly, from about 35 degrees during the day to close to freezing at night.
I suggest you take them out of the greenhouse and try them inside your house.
The seed raising mix should never be allowed to dry out.
Place inside a plastic bag, with a few breathing holes and place close to a South facing window, preferbly in a non-heated room.
For more information, please see the culture notes.
How do I espalier a camellia?
The best camellia to espalier is a sasanqua.
Tie the vertical to the frame and allow it to grow to the desired height, and stop the growing tip.
Bend the lateral branches horizontally and tie to the frame.
Allow then to grow to the desired length and stop the growth.
How do I grow frangipani from cuttings?
Late spring is the best time to take cuttings.
The cuttings can be quite large, up to 30cm long.
Cut off all the leaves.
Leave the cuttings in a cool dry spot for a week to allow the cut surfaces to dry up.
Then root the cuttings in moist pumice sand.
To collect seeds, should I cut the seed heads of poppies now or let them ripen on the plant?
Harvest the seed pods when they start to turn brown, but before the seeds start to come out from the pod.
Hang the pods upside down inside a paper bag and allow the seeds to fall naturally into the bag.
When is the right season to grow strawberry foxgloves? Can they be grown in a pot and be put on a porch outside?
You start the seeds either in autumn or spring.
Most plants take two seasons to flower.
They can be grown in 8 inch pots, but will need to be watered often during the growing season.
Divide and repot after flowering to keep plants growing yearly.
I live in the UK and I have today purchased from a Garden Centre a beautiful Gloriosa superba which I am going to keep as a house plant. What is the right way to dead head it please?
It depends a bit on where you live.
Here in Auckland, New Zealand, Gloriosa superba grows almost like a weed.
The plant is so rampant that it makes little difference whether it is dead headed or not.
In colder areass, dead heading would help conserve the plants energy.
To dead head, simply bend the flower where it joins the "stalk" and it will snap off cleanly.
The empty green stalks will soon turn brown, although they do not fall off.
If you think they are unsightly, you can cut them off close to the vine, but be careful to not damage the vine.
Gloriosa vines seldom branch and when they do, it is always at the tip - a broken vine will not branch.
Once broken, that is flowering for the year.
The plant is also severely weakened.
The other thing is Gloriosa likes full sun, or near full sun.
When grown indoors, it needs to get as much light as possible.
Grown in insufficient light, the vines will be splindly and weak, and will not flower.
Is it alright to germinate chilly seeds in a humid environment?
Yes, the humid environment actually helps with germination.
Humidity can be increased by placing the seeds in a pot and enclosing the pot inside a plastic bag.
Once the seedlings emerge, gradually remove from the humid environment.
This will harden the seedlings to enable them to live outdoors.
How do I grow chillies over the winter?
Chillies and peppers are warm growing plants and as such, unsuitable for growing over the winter.
However, there is a species, Capsicum pubescens, commonly known as Rocoto, is a cool grower and will grow through the winter in warmer parts of the country.
Unlike other chillies that typically only lasts a year, this species is also long lived, plants often growing to large old bushes.
See also Chillies and Peppers.
I have just dug up my dailias. How do I divide them?
Dahlia tubers that are freshly dug up in the autumn will not have visible eyes.
Store these in sawdust in a cool dry place to over winter.
In the spring, around October, eyes on the crown will start to swell up.
The plant can now be divided, making sure each division has a tuber and a segment of the crown with at least one eye.
Dahlias do not grow eyes on their tubers, so take extra care when digging the tubers up as not to break them from the crown.
See also Dahlia.
Can galangal be planted now (in the Winter)
In warmer areas, galangal can be planted at any time of the year.
In colder areas with heavy frosts, it is best to grow galangal in a pot first and then plant out in the spring.
This will allow time for the plant to get established before winter.
See also Culture and Germination - Galangal.
Can galangal be grown in Christchurch
The short answer is yes.
The long answer is established plants are more likely to survive the frost.
Plants should be started in the spring and grown well, but hard over the summer.
Some form of shelter is beneficial during winter.
This can be in the form of the dead tops being left on through out winter and only removed in the spring.
When should I prune evergreen shrubs and trees
Auckland and areas north do not get heavy frosts, so shrubs and trees can be prunned in the autumn.
If the autumn or winter has been warm, it is likely the evergreen shrubs and trees will resprout.
In cooler areas, it is best to wait for spring before prunning so that frosts do not damage any of the regrowths.
Evergreens can also be prunned in late summer.
Summer prunning causes the plants to grow slower.
Why is my epidendrum orchid not flowering
There can be several reasons why epidendrum orchids do not flower.
The most common is lack of light.
These orchids like a lot of light and can even stand full sun.
Move the plant to a brighter spot.
The other reasons are lack of water - these orchids love water but the roots must not sit in pooling water.
Lack of water stuns growth and as they flower on the ends of new growth, lack of growth equates to lack of flowers.
The final reason could be due to pruning.
These are tall orchids but if the canes are pruned, they will never flower.
If you allow the orchid to be frosted, this is equivalent to pruning.
The top of the canes will be killed by the frost and the plant will not flower.
Provide some winter protection.
Will manuka grow in hot climates such as Florida
The short answer is I don't know for sure.
The long answer is they will most probably grow, but with a less seasonal climate, they may not flower or may not flower well.
Also, there may be diseases and pests in Florida which manuka has not encountered before and may succumb.
On the other hand, manuka may find the new home very much to its liking, and lacking any natural enemies, it thrives, spreads and subsequently becomes a weed.
I know this doesn't give you a direct answer, but introducing plants to a new climate zone is risky.
There are lots of unknowns.
When growing Dragon Fruit, is it necessary to add sand to the potting mix? Can I plant it in terracotta pots?
Good drainage is necessary to grow Dragon Fruit well, as it reduces the chance of rot.
This is especially true with our wet climate.
Adding pumice sand to the potting mix is one way of achieving this.
While I do not use terracotta pots, there is no reason why terracotta pots cannot be used.
On the other hand, plastic pots with the right potting mix will also be fine.
See also:Culture and Germination - Dragon Fruit
Can I use ordinary compost to grow Calanthes and Thunias
The short answer is OK for Calanthe but use orchid bark for Thunia.
For a more detailed answer, please read their respective culture notes: Culture and Germination - Calanthe & Culture and Germination - Thunia.
The cut stem on my galangal has rotten away and the plant hasn't grown but the rhizome is still firm. What should I do?
The cut stem will not grow anymore, so it is normal for it to eventually rot away.
The cool weather of winter will slow down the growth of galangal, so it is normal for new growths to not appear until the spring.
If the rhizome is still firm, the plant is healthy.
It should not be soft or smelly.
Some wrinkling is normal but excessive wrinkling indicates that the plant has been severely water stressed - unusual in winter.
For newly planted rhizomes, keep the potting just moist, but not soaking wet, until the plant has started growing.
Is it easy to save chilly seeds and keep them?
Yes, it is very easy to save chilly seeds.
Please see the Saving Seeds for the Home Gardener article for more information
Is Tigridia Sensitive to Frost?
Jockey Caps (Tigridia pavonia) is a half hardy bulb, but it is not the frost that you need to be worried about.
It is the combination of cold and wet that will kill.
They are a summer growing bulb and will lose their leaves in the winter.
What I do is plant them in pots (they are very small bulbs) and then bring the pot into the garage during the winter.
Why hasn't my melon seeds germinated yet. They were sown directly into the ground.
Melon seeds are large and normally germinates quickly.
This spring however, it has been very wet, and sowing directly into the ground risks rotting the seeds.
There is no hard and fast rule, but a combination of cool weather, wet ground and poor drainage encourages parasitic fungi and bacteria.
The alternative is to sow into pots, using seed raising mix.
Keep the mix moist but not soaking wet.
The seeds need some warmth to germinate, minimum 9°C.
For more information see Culture and Germination - Melons.
My chilly seedlings outdoors have grown to 100mm tall but only have a pair of leaves and have stopped growing. What is wrong?
Chilly seedlings normally grow to around 40mm at the two leaf stage.
It sounds like your plants are not getting enough light and have become very lanky.
The other issue could be warmth.
Chilly seeds should be started indoors or under glass and only transplanted when large enough.
The small seedlings appreciate extra warmth.
Growth could be stunted if grown in too cool conditions.
Move the seedlings indoors and gradually move them to brighter light.
I started coreopsis seeds in peat pots and placed them inside the hot water cylinder cupboard. Whey have they not germinated?
Coreopsis require cooler conditions to germinate (and some light too, but not too much).
Use a good seed raising mix, sow the seeds on the surface of the mix, or shalowly burried.
Cover the pots with plastic to keep in humidity and germinate in outside temperatures.