Study up on what plants ward off pests. Like onions and marigolds. Then be prepared to plant those along with your tomatoes and cucumbers and pumpkins, and maybe your watermelon too. Go to the library and look up some information. Your local gardening club organization could probably help too.

Hello!

If you are beginner, you should know that there are easy plants and difficult plants.
It also depends on the climate where you live.
I remenber that tomato is easier.
If you use container,water them a lot when the surface of the soil got dry.(some plants prefer wet though)
And don’t be hurry, if you plants them outside too early, they’ll die because of the cold.

And if you plant basil next to tomato, they’ll encourage to grow together.
They are called companion plants.
And, if you plants mints, cockroaches don’t come.
If you plants camomile, the plants around them will be better.
Many of herb have a scent that pest don’t come.
Also, greenhouse is good to shut out them.

And there is one tips for you. You can start it soon.
Buy greenonion at an organic supermarket, and use the top half ( remain 10-15cm and root)
and put the root in a glass of water.
They’ll grow very soon, and you can harvest twice or three times, so they’re organic.
It works with the vegitable with roots, but I think that greenonion is a easiest.

The best start is good soil and healthy plants. One of the main reason for bugs is unhealthy soil, watering problems and inferior plants.

If you keep your garden free of weeds and leaves and places insects can hide; its easier to control them.

Companion planting helps with controlling insects. Tomatoes like beans. Onion and garlic control many pests along with marigolds and geraniums.

One of the worst garden insect problems you will have with your choices are cucumber beetles. They love cucumbers, squash and pumpkins. Plant a radish near the plants and let it go to seed. This stops any cucumber beetle problems. Also cover the plants when they are tender and young. This is when they are most susceptible to injury. I cover mine with Terra cotta pots until they are about 6 inches high.

I have not used any chemicals in my gardens of over 10 years. I have almost no insect damage. Denise

Dig plenty of organic matter in your soil i.e. well rotted manure and compost. Healthy soil leads to healthy plants. The healthier the plants, less likely are they to be affected by pests and diseases.

Things can’t be achieved overnight. It will be some time, may be two or three seasons, before a population of good bugs develop and they will do most of the work for you. learn to identify the good bugs. There’s plenty on the Internet to read.

Try to stay away from home made sprays while the population of good bugs are building. even if u use organic sprays, use them as spot sprays. Never ever mass spray your garden. It will kill your friends.

Also try and read about companion planting. Plants grown in right combinations can make a lot of difference.

There is lot of information on Internet about it or you could find books in your local library.

All the things that you mentioned are very easy to grow. Give your plants healthy soil, regular watering, room to grow and plenty of air circulation.
Good luck!