I have always been under the impression that when growing tomatoes from
seed, they should not be planted into their final position until they
are in flower. How important is this and what is the reason?

If you wait until the plant is in flower to put out, you trick the plant and it may then produce an early truss of fruit as the plant feels under stress.  So this is done to give an earlier crop.

We are told that one of the health giving attributes of tomatoes is
the fact that they contain lycopene, and that this is the substance that
gives them their red colour.
Does this mean that tomatoes of other colours, e.g. yellow, do not
contain lycopene?

Yellow tomatoes do have less lycopene than red tomatoes and are therefore less nutritious.  Black varieties have the most lycopene.

What is the cause of a corky growth on a cactus which blooms well?

The cactus is unwell and this may be as a result of vine weevil infection, a fungal or a bacterial infection.  The top should be rocked back and forth to see how stable it is.  It should be kept away from other plants.
As a general tip, when adding any indoor plant to your collection, keep it separate for 6 weeks to ensure that it does not have any infections to pass on.

How do you grow blueberries in Hampshire?

They are high in antioxidants and acid lovers. On a chalk soil they must be grown in a container, watered with rain water and planted in ericaceous compost.  They are greedy so add manure if possible.  Add 2 inches of mulch. You get a better crop if you have 3 plants, which can be different varieties, to give an early, middle and late crop.  Birds like blueberries so they need to be netted, with the net held above the plant.

Help!  Growing Proteas.  Seed bought as a gift from South Africa, the instructions are quite complicated.

6 different varieties of seeds were shown in a packet.  2 of these would be easy and the others more difficult.  They want acid compost and low nutrients and little watering.  Germination needs the chemicals from smoke and some impregnated tissues were included.  Some of the seeds were hairy so these could have the hairs burnt off to help germination.  Boiling water could be poured over the seeds and left to soak for 24 hours.  This method can also be used for Sweet Peas.

A recent television programme suggested that all but 1 eye shoot should be rubbed off a chitted potato.  Another recent advice said leave 2.  Alan Titchmarsh says you don’t need to chit at all.  Who’s right?

The more chits left the more potatoes, but of varying size.  3 sprouts are recommended.  Some modern cultivars do not produce many chits.

I am told that potatoes and tomatoes should not be grown too close together, as cross-pollination will affect the tomato fruit.  How close is too close?

A camellia in a pot flowers well, but the leaves go yellow.  It is fed.  What is the problem?

This could be caused by either sooty mould or scale.  Treat with Provado and if the infection is bad it may require repeat treatments.  Camellias may shed a good proportion of their leaves after winter

Is it possible for roots of Leyland leylandii to survive in the ground when severed from the tree

Why does Swede sometimes not develop into globular roots as they are supposed to?

How long does it take for seed collected from alliums to produce flowering plants?

A Mature Conference Pear tree, 10 feet tall, is more than 20 years old. In 2007 and 2008 it had an excellent fruit crop. In 2009 pear mite severely affected the leaves and fruit, and gave a very poor crop, less than 10% of previous years. Believe it was caused by the wetter than usual summer. Is this likely, or is there any protection that can be taken? Removing leaves and fruit left the tree almost bare.

Dig up and divide the plant and gently tease out the grass

Cut back flower stems when finished to their base.  Mist 1 or 2 times a week and water sparingly with rainwater.  If kept in a bathroom water less, as the plant will take up moisture through its roots.  Feed with ½ strength Tomato Fertilizer.

These had been planted too deeply.  They should be resting on top of the compost and be kept in a good but indirect light position.

The caterpillar of the moth, which burrows into the leaves, causes the damage.  There is a new natural cure on the market.  Otherwise cover with enviromesh or fleece.  If you have had an infection, clear all debris from the site and do not compost anything.  Fleece will also deter the Flea Beetle.

Care of a Lemon Tree.

It would probably tolerate down to 5 degrees but this may cause leaves to fall and lose of crop for that year.  The plant can be made hardier if kept at 3-4 degrees.

A 3 year old, 5-foot shrub could be moved.  It could be pruned back hard after flowering to reduce size.  Otherwise move with a substantial root ball.

Put a base of manure in the bag, then compost.  Do not put too many potatoes in, 4 or 5 in a large bag.  Water when the plants come into flower or when the haulms are 1 foot above the bag.

Lamium was recommended.  There are now new varieties and the Chicago Botanic Garden website is a good source of information.