How do I know if my heathers are dying? They’ve turned a funny colour – does this mean I am overwatering or underwatering them? HM, Caerleon

Most heathers fall into two groups. Heathers that are in flower now are called Callunas and are quite fussy with their soil requirements (they like acid soil) These are the heathers that grow wild on our mountains and this is why they are called the black mountains as the foliage goes dark in the winter.

The second main group are called Erica and these flower in the spring. They are not fussy plants and some have bright golden foliage which can look stunning planted with dwarf conifers. Heathers benefit from pruning after flowering and an acid plant feed during the growing season.

How do I stop my petrol lawn mower fuel going stale and damaging the mower? TW, Newport

I'm no mechanic but you should drain the fuel tank before you put the mower to bed for the winter.

I’m growing just two tomatoes in my greenhouse – Alicante and Moneymaker. I’ve got a wonderful crop – about six trusses on each one but I’ve got blossom and rot and now some are splitting. They are in a 12x8 greenhouse so they are well ventilated and they are fed tomorite and watered regularly. They are grown ring culture on a bed of gravel with soil underneath. I would be very grateful for any advice you could give me. BP, Newport

The plants do not have enough water at fruit set and when the fruit are developing. They only have to dry out a little once and the damage is done.

Next year you could remove the gravel and put the rings directly on the soil. This should eliminate the problem.

What flowering plants would you recommend to have in my garden over the winter? LL, Pontypool

There are some fantastic winter flowering plants to chose from many of which are heavily scented. Here are a few of my favourites: Daphne odora, Hamamellis (witch hazel), Winter aconite, snow drops, Camellia sasanqua, Sarcococca (Christmas box)