You will pay at least twice as much for yellow-tomatoes at any shop, so the answer is to grow your own.
Choosing Which yellow-tomato Plants to Buy
Buy your seed from a specialist seed company. Browse their websites until you find one supplier who has two or three types of yellow-tomato plant. Order at least two types of seed, you can always sell or give your spare plants away in June.
In late spring, exactly when depends on where you live, plant the tomato seeds in compartmented seed trays of damp compost on an inside window sill, ideally in a conservatory. Be sure to LABEL which variety of yellow-tomato plant is which.
When the seedlings are about 3 inches high, transplant them to 2 inch diameter plant pots of damp compost. Keep them inside until ALL risk of frost has passed.
Get your tomatoes used to being outside by taking them out in the day and bringing them in at night. If you keep all your 2 inch pots in trays, a separate tray for each different type of yellow-tomato, it is not too bad a chore to do.
After a week of the hardening off procedure you can leave them outside at night, unless the temperature is going below 5 degrees C ( 41 degrees F).
If you are absolutely certain that temperatures are not going to fall below this critical temperature you can plant out your tomato babies. Keep half of each variety for three more weeks, in case the frost surprises you.
There are three ways in which you can have your own yellow-tomato plants.You can use grow bags, containers, or you can grow them in the ground.
Growing yellow-tomato Plants in Grow-Bags
Grow-Bags hold either 20 litres or 40 litres of compost. The compost is not the soil based type and these bags are not usually too heavy for most people. Buy your Grow-Bag in September, when most retailers are trying to shift their stock at heavy discounts. You can get them for 25% of the original price (75% off). Cover them and protect from the rain if you leave them outside, or all the fertilizer will wash out.
Although you will want to put 3 or 4 plants in each grow-bag, firmly resist this temptation. You should only put one into each, but certainly no more than two.
You will not be able to move the grow-bag once you have planted your tomato seedlings, so position the bags carefully. You will need to check the bag every single day to see if it needs water. If the compost does not dampen a piece of newspaper held against it for 10 seconds you need to water.
Grow bags do not hold much fertilizer, especially own-brand ones, so water with tomato fertilizer from about June, when your yellow-tomato plants should be developing nicely.
Support for traditional varieties in a grow-bag is difficult and you might be better off choosing at least one bush variety that needs no cane or staking. If you are growing a traditional variety of yellow-tomato then tie three 4 foot canes together at one end. Splay out the other ends of the canes to make a tipi . Plant the splayed canes in the grow-bag. Next put another 4 foot cane straight up from the tomato plant to the apex of the tipi.
Shade your grow-bag when it is hot and keep it watered with 2 gallons of tomato fertilizer or water a day in summer.
Growing yellow-tomato Plants in Containers
Forget those itsy bitsy plant pots that the garden centres call tomato pots. Use a large container, at least 5 gallons (25 litres). These tend to be expensive, so unless you have a spare one lying around just buy a black builders' bucket and drill holes in the bottom. Fill it with a mixture of sterilized soil and ordinary grow-bag type compost. Wet the compost thoroughly. Leave to stand for a few hours then plant one seedling in the container.
If you are growing conventional yellow-tomato plants put a 6 foot cane all the way to the bottom of the container, so you have 4-5 feet sticking out. You do not need a cane if you are growing the bush type of yellow-tomato.
Keep the container near the house, where it is easy to check and to water. It will need watering every day, or stand the container in a giant saucer of water. The water travels up the soil by capillary action. This is by far the best way to water tomatoes.
As an alternative to the giant saucer take a length of 3 or 4 inch diameter piping. Block it up at one end. Drill holes all along and all around the pipe. Push the sealed end of the pipe into your tomato container and leave the open end just above the surface. When your yellow-tomato plants need water, just fill the pipe with water and it will percolate out into the soil.
Growing yellow-tomato Plants in the Soil
Any tomato plants grown in the soil are likely to be more healthy because the roots have the space they need. The roots of a yellow-tomato plant spread up to two feet in all directions.
The roots go two feet down as well, so your soil will need to be deep, with plenty of fertilizer and plenty of humus. You can add humus to your soil by adding compost, preferably your own, but bags of compost will have a similar effect, without adding weeds to the soil. You need to plant your tomato seedlings about three feet apart. This will allow you to get to them easily to tie them up and to pinch out stems where this is necessary. Wide spacing also makes for more healthy plants because they will be less liable to develop fungal infections such as Black Spot. You will need to use mulch or landscape paper between the tomatoes to keep weeds down
You can use the drainpipe trick for deep watering here, too.