Mericrest can fruit alone, but it still benefits from a partner. Most peaches and nectarines can fruit alone, but a second compatible tree often improves fruit set and reliability. It flowers in mid bloom, which is worth knowing if you add a second tree later. Usually grown in USDA zones 5-8.
The good news is you have real choices here. The strongest partners are Harko and Redgold. Any one of them is enough to get fruit set going. If your nursery has none of those, Fantasia, Flavortop, or Sunfre will also do the job. If you plant two nectarines, keep them close enough for bees to move easily between them. A second tree within about 50 feet is usually enough.
One thing to keep in mind. Chill note: About 800 chill hours. Handled conservatively as a mid-bloom nectarine. Another peach or nectarine nearby can still improve crop consistency even though it is self-fruitful.
To put that into practice: at a minimum, one self-fruitful nectarine is usually enough to get fruit. Better still, plant two nectarines with overlapping bloom if you want better fruit set, larger crops, and extra spring insurance. If you already have one nectarine, add a second only if you want to improve crop reliability rather than simply get any fruit at all.
