How do I prepare borders for new plants?

[MrTurtleLikesKisses]

I am trying to sort out the garden in our rented home and I don't really know what I'm doing.
I think the garden was probably lovely once but has since been neglected.
There are two small borders either side of the garden. They were each pretty much filled by a palm and something else (horrible spiky thing, began with "m" I think). We've chopped down and dug out the spiky things so now it's just the palms.
So, what do I do to the beds to get them ready for new plants? I've turned them over but they're FULL of tiny little roots, lots and lots of bulbs (I've put them to one side if they're ok, and got rid if they're rotten). Am I doing the right thing? I've got lots of compost, can I just top them up with it? Do I need a fertiliser? I don't want to get rid of stuff if it's good for the soil!
I have tried to search online for all this but most sites assume at least some gardening knowledge!

[Valentine2]

Placemarking

[pansydePotter]

There should be no need to fertilise this year if you are putting on fresh Compost. Also when you buy plants from a nursery the soil in the pot usually contains nutrients. Over feeding can cause problems so err on the side of caution. Generally, in Spring, I sprinkle A general fertiliser around, something like Fish Blood and Bone. I have beeen gardening for half a century and still don't know if it is a waste of money. Most important thing with a new garden is to water regularly until the plants are established. This time of year the top of the garden will dry out very quickly. A good soaking late evening is best, but if it has been very hot or windy then a drink during the day too. Usually a plant will tell you if it is thirsty by its drooping leaves.

[MrTurtleLikesKisses]

Ok, thank you! I bought some Fish blood and bone so I will keep it for next year.

[JT05]

Don't forget to fertilise any existing roses and shrubs.

[claraschu]

I am a terrible gardener, but my lovely neighbour told me to dig a hole twice as large as the plant root ball, put in a handful of tiny pebbles (clayey soil here) a large handful of well rotted manure, and a large handful of John Innes planting soil. I followed her instructions and my borders look 10 times better than ever before.

[MrTurtleLikesKisses]

Thanks for the tips! I will fertilise the two remaining palms and will remember that tip when I eventually put the new plants in.
I'm still digging and turning over the borders. They are FULL of old root balls so I'm trying to break it all up and get rid of some of it before I add the compost.

[pansydePotter]

Sorry if I sound like I am contradicting myself, but , from your later post it seems that you are digging out quite deeply and pulling up old shrubs. This deep soil which has previously supported shrubs maybe impoverished and so a scattering of the FB&B is probably a good idea. Feeding a garden is a bit like taking Vitamins, not an exact science.

[MrTurtleLikesKisses]

Pansy, I've added some along with the compost today, thank you.